core/num/uint_macros.rs
1macro_rules! uint_impl {
2 (
3 Self = $SelfT:ty,
4 ActualT = $ActualT:ident,
5 SignedT = $SignedT:ident,
6
7 // These are all for use *only* in doc comments.
8 // As such, they're all passed as literals -- passing them as a string
9 // literal is fine if they need to be multiple code tokens.
10 // In non-comments, use the associated constants rather than these.
11 BITS = $BITS:literal,
12 BITS_MINUS_ONE = $BITS_MINUS_ONE:literal,
13 MAX = $MaxV:literal,
14 rot = $rot:literal,
15 rot_op = $rot_op:literal,
16 rot_result = $rot_result:literal,
17 fsh_op = $fsh_op:literal,
18 fshl_result = $fshl_result:literal,
19 fshr_result = $fshr_result:literal,
20 clmul_lhs = $clmul_lhs:literal,
21 clmul_rhs = $clmul_rhs:literal,
22 clmul_result = $clmul_result:literal,
23 swap_op = $swap_op:literal,
24 swapped = $swapped:literal,
25 reversed = $reversed:literal,
26 le_bytes = $le_bytes:literal,
27 be_bytes = $be_bytes:literal,
28 to_xe_bytes_doc = $to_xe_bytes_doc:expr,
29 from_xe_bytes_doc = $from_xe_bytes_doc:expr,
30 bound_condition = $bound_condition:literal,
31 ) => {
32 /// The smallest value that can be represented by this integer type.
33 ///
34 /// # Examples
35 ///
36 /// ```
37 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN, 0);")]
38 /// ```
39 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
40 pub const MIN: Self = 0;
41
42 /// The largest value that can be represented by this integer type
43 #[doc = concat!("(2<sup>", $BITS, "</sup> − 1", $bound_condition, ").")]
44 ///
45 /// # Examples
46 ///
47 /// ```
48 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX, ", stringify!($MaxV), ");")]
49 /// ```
50 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
51 pub const MAX: Self = !0;
52
53 /// The size of this integer type in bits.
54 ///
55 /// # Examples
56 ///
57 /// ```
58 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
59 /// ```
60 #[stable(feature = "int_bits_const", since = "1.53.0")]
61 pub const BITS: u32 = Self::MAX.count_ones();
62
63 /// Returns the number of ones in the binary representation of `self`.
64 ///
65 /// # Examples
66 ///
67 /// ```
68 #[doc = concat!("let n = 0b01001100", stringify!($SelfT), ";")]
69 /// assert_eq!(n.count_ones(), 3);
70 ///
71 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
72 #[doc = concat!("assert_eq!(max.count_ones(), ", stringify!($BITS), ");")]
73 ///
74 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
75 /// assert_eq!(zero.count_ones(), 0);
76 /// ```
77 #[stable(feature = "rust1", since = "1.0.0")]
78 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
79 #[doc(alias = "popcount")]
80 #[doc(alias = "popcnt")]
81 #[must_use = "this returns the result of the operation, \
82 without modifying the original"]
83 #[inline(always)]
84 pub const fn count_ones(self) -> u32 {
85 return intrinsics::ctpop(self);
86 }
87
88 /// Returns the number of zeros in the binary representation of `self`.
89 ///
90 /// # Examples
91 ///
92 /// ```
93 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
94 #[doc = concat!("assert_eq!(zero.count_zeros(), ", stringify!($BITS), ");")]
95 ///
96 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
97 /// assert_eq!(max.count_zeros(), 0);
98 /// ```
99 ///
100 /// This is heavily dependent on the width of the type, and thus
101 /// might give surprising results depending on type inference:
102 /// ```
103 /// # fn foo(_: u8) {}
104 /// # fn bar(_: u16) {}
105 /// let lucky = 7;
106 /// foo(lucky);
107 /// assert_eq!(lucky.count_zeros(), 5);
108 /// assert_eq!(lucky.count_ones(), 3);
109 ///
110 /// let lucky = 7;
111 /// bar(lucky);
112 /// assert_eq!(lucky.count_zeros(), 13);
113 /// assert_eq!(lucky.count_ones(), 3);
114 /// ```
115 /// You might want to use [`Self::count_ones`] instead, or emphasize
116 /// the type you're using in the call rather than method syntax:
117 /// ```
118 /// let small = 1;
119 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::count_zeros(small), ", stringify!($BITS_MINUS_ONE) ,");")]
120 /// ```
121 #[stable(feature = "rust1", since = "1.0.0")]
122 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
123 #[must_use = "this returns the result of the operation, \
124 without modifying the original"]
125 #[inline(always)]
126 pub const fn count_zeros(self) -> u32 {
127 (!self).count_ones()
128 }
129
130 /// Returns the number of leading zeros in the binary representation of `self`.
131 ///
132 /// Depending on what you're doing with the value, you might also be interested in the
133 /// [`ilog2`] function which returns a consistent number, even if the type widens.
134 ///
135 /// # Examples
136 ///
137 /// ```
138 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX >> 2;")]
139 /// assert_eq!(n.leading_zeros(), 2);
140 ///
141 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
142 #[doc = concat!("assert_eq!(zero.leading_zeros(), ", stringify!($BITS), ");")]
143 ///
144 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
145 /// assert_eq!(max.leading_zeros(), 0);
146 /// ```
147 #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
148 #[stable(feature = "rust1", since = "1.0.0")]
149 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
150 #[must_use = "this returns the result of the operation, \
151 without modifying the original"]
152 #[inline(always)]
153 pub const fn leading_zeros(self) -> u32 {
154 return intrinsics::ctlz(self as $ActualT);
155 }
156
157 /// Returns the number of trailing zeros in the binary representation
158 /// of `self`.
159 ///
160 /// # Examples
161 ///
162 /// ```
163 #[doc = concat!("let n = 0b0101000", stringify!($SelfT), ";")]
164 /// assert_eq!(n.trailing_zeros(), 3);
165 ///
166 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
167 #[doc = concat!("assert_eq!(zero.trailing_zeros(), ", stringify!($BITS), ");")]
168 ///
169 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
170 #[doc = concat!("assert_eq!(max.trailing_zeros(), 0);")]
171 /// ```
172 #[stable(feature = "rust1", since = "1.0.0")]
173 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
174 #[must_use = "this returns the result of the operation, \
175 without modifying the original"]
176 #[inline(always)]
177 pub const fn trailing_zeros(self) -> u32 {
178 return intrinsics::cttz(self);
179 }
180
181 /// Returns the number of leading ones in the binary representation of `self`.
182 ///
183 /// # Examples
184 ///
185 /// ```
186 #[doc = concat!("let n = !(", stringify!($SelfT), "::MAX >> 2);")]
187 /// assert_eq!(n.leading_ones(), 2);
188 ///
189 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
190 /// assert_eq!(zero.leading_ones(), 0);
191 ///
192 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
193 #[doc = concat!("assert_eq!(max.leading_ones(), ", stringify!($BITS), ");")]
194 /// ```
195 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
196 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
197 #[must_use = "this returns the result of the operation, \
198 without modifying the original"]
199 #[inline(always)]
200 pub const fn leading_ones(self) -> u32 {
201 (!self).leading_zeros()
202 }
203
204 /// Returns the number of trailing ones in the binary representation
205 /// of `self`.
206 ///
207 /// # Examples
208 ///
209 /// ```
210 #[doc = concat!("let n = 0b1010111", stringify!($SelfT), ";")]
211 /// assert_eq!(n.trailing_ones(), 3);
212 ///
213 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
214 /// assert_eq!(zero.trailing_ones(), 0);
215 ///
216 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
217 #[doc = concat!("assert_eq!(max.trailing_ones(), ", stringify!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
236 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
237 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
238 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
239 /// ```
240 #[stable(feature = "uint_bit_width", since = "1.97.0")]
241 #[rustc_const_stable(feature = "uint_bit_width", since = "1.97.0")]
242 #[must_use = "this returns the result of the operation, \
243 without modifying the original"]
244 #[inline(always)]
245 pub const fn bit_width(self) -> u32 {
246 Self::BITS - self.leading_zeros()
247 }
248
249 /// Returns `self` with only the most significant bit set, or `0` if
250 /// the input is `0`.
251 ///
252 /// # Examples
253 ///
254 /// ```
255 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
256 ///
257 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
258 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
259 /// ```
260 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
261 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
262 #[must_use = "this returns the result of the operation, \
263 without modifying the original"]
264 #[inline(always)]
265 pub const fn isolate_highest_one(self) -> Self {
266 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
267 }
268
269 /// Returns `self` with only the least significant bit set, or `0` if
270 /// the input is `0`.
271 ///
272 /// # Examples
273 ///
274 /// ```
275 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
276 ///
277 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
278 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
279 /// ```
280 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
281 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
282 #[must_use = "this returns the result of the operation, \
283 without modifying the original"]
284 #[inline(always)]
285 pub const fn isolate_lowest_one(self) -> Self {
286 self & self.wrapping_neg()
287 }
288
289 /// Returns the index of the highest bit set to one in `self`, or `None`
290 /// if `self` is `0`.
291 ///
292 /// Note that this is equivalent to [`checked_ilog2`](Self::checked_ilog2).
293 ///
294 /// # Examples
295 ///
296 /// ```
297 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
298 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
299 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
300 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
301 /// ```
302 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
303 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
304 #[must_use = "this returns the result of the operation, \
305 without modifying the original"]
306 #[inline(always)]
307 pub const fn highest_one(self) -> Option<u32> {
308 match NonZero::new(self) {
309 Some(v) => Some(v.highest_one()),
310 None => None,
311 }
312 }
313
314 /// Returns the index of the lowest bit set to one in `self`, or `None`
315 /// if `self` is `0`.
316 ///
317 /// # Examples
318 ///
319 /// ```
320 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
321 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
322 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
323 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
324 /// ```
325 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
326 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
327 #[must_use = "this returns the result of the operation, \
328 without modifying the original"]
329 #[inline(always)]
330 pub const fn lowest_one(self) -> Option<u32> {
331 match NonZero::new(self) {
332 Some(v) => Some(v.lowest_one()),
333 None => None,
334 }
335 }
336
337 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
338 ///
339 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
340 /// the same.
341 ///
342 /// # Examples
343 ///
344 /// ```
345 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
346 ///
347 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
348 /// ```
349 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
350 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
351 #[must_use = "this returns the result of the operation, \
352 without modifying the original"]
353 #[inline(always)]
354 pub const fn cast_signed(self) -> $SignedT {
355 self as $SignedT
356 }
357
358 /// Saturating conversion of `self` to a signed integer of the same size.
359 ///
360 /// The signed integer's maximum value is returned if `self` is larger
361 /// than the maximum positive value representable by the signed integer.
362 ///
363 /// For other kinds of signed integer casts, see
364 /// [`cast_signed`](Self::cast_signed),
365 /// [`checked_cast_signed`](Self::checked_cast_signed),
366 /// or [`strict_cast_signed`](Self::strict_cast_signed).
367 ///
368 /// # Examples
369 ///
370 /// ```
371 /// #![feature(integer_cast_extras)]
372 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
373 ///
374 #[doc = concat!("assert_eq!(n.saturating_cast_signed(), ", stringify!($SignedT), "::MAX);")]
375 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".saturating_cast_signed(), 64", stringify!($SignedT), ");")]
376 /// ```
377 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
378 #[unstable(feature = "integer_cast_extras", issue = "154650")]
379 #[must_use = "this returns the result of the operation, \
380 without modifying the original"]
381 #[inline(always)]
382 pub const fn saturating_cast_signed(self) -> $SignedT {
383 // Clamp to the signed integer max size, which is ActualT::MAX >> 1.
384 if self <= <$SignedT>::MAX.cast_unsigned() {
385 self.cast_signed()
386 } else {
387 <$SignedT>::MAX
388 }
389 }
390
391 /// Checked conversion of `self` to a signed integer of the same size,
392 /// returning `None` if `self` is larger than the signed integer's
393 /// maximum value.
394 ///
395 /// For other kinds of signed integer casts, see
396 /// [`cast_signed`](Self::cast_signed),
397 /// [`saturating_cast_signed`](Self::saturating_cast_signed),
398 /// or [`strict_cast_signed`](Self::strict_cast_signed).
399 ///
400 /// # Examples
401 ///
402 /// ```
403 /// #![feature(integer_cast_extras)]
404 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
405 ///
406 #[doc = concat!("assert_eq!(n.checked_cast_signed(), None);")]
407 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_cast_signed(), Some(64", stringify!($SignedT), "));")]
408 /// ```
409 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
410 #[unstable(feature = "integer_cast_extras", issue = "154650")]
411 #[must_use = "this returns the result of the operation, \
412 without modifying the original"]
413 #[inline(always)]
414 pub const fn checked_cast_signed(self) -> Option<$SignedT> {
415 if self <= <$SignedT>::MAX.cast_unsigned() {
416 Some(self.cast_signed())
417 } else {
418 None
419 }
420 }
421
422 /// Strict conversion of `self` to a signed integer of the same size,
423 /// which panics if `self` is larger than the signed integer's maximum
424 /// value.
425 ///
426 /// For other kinds of signed integer casts, see
427 /// [`cast_signed`](Self::cast_signed),
428 /// [`checked_cast_signed`](Self::checked_cast_signed),
429 /// or [`saturating_cast_signed`](Self::saturating_cast_signed).
430 ///
431 /// # Examples
432 ///
433 /// ```should_panic
434 /// #![feature(integer_cast_extras)]
435 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_cast_signed();")]
436 /// ```
437 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
438 #[unstable(feature = "integer_cast_extras", issue = "154650")]
439 #[must_use = "this returns the result of the operation, \
440 without modifying the original"]
441 #[inline]
442 #[track_caller]
443 pub const fn strict_cast_signed(self) -> $SignedT {
444 match self.checked_cast_signed() {
445 Some(n) => n,
446 None => imp::overflow_panic::cast_integer(),
447 }
448 }
449
450 /// Shifts the bits to the left by a specified amount, `n`,
451 /// wrapping the truncated bits to the end of the resulting integer.
452 ///
453 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
454 /// particular, a rotation by the number of bits in `self` returns the input value
455 /// unchanged.
456 ///
457 /// Please note this isn't the same operation as the `<<` shifting operator!
458 ///
459 /// # Examples
460 ///
461 /// ```
462 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
463 #[doc = concat!("let m = ", $rot_result, ";")]
464 ///
465 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
466 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
467 /// ```
468 #[stable(feature = "rust1", since = "1.0.0")]
469 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
470 #[must_use = "this returns the result of the operation, \
471 without modifying the original"]
472 #[inline(always)]
473 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
474 pub const fn rotate_left(self, n: u32) -> Self {
475 return intrinsics::rotate_left(self, n);
476 }
477
478 /// Shifts the bits to the right by a specified amount, `n`,
479 /// wrapping the truncated bits to the beginning of the resulting
480 /// integer.
481 ///
482 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
483 /// particular, a rotation by the number of bits in `self` returns the input value
484 /// unchanged.
485 ///
486 /// Please note this isn't the same operation as the `>>` shifting operator!
487 ///
488 /// # Examples
489 ///
490 /// ```
491 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
492 #[doc = concat!("let m = ", $rot_op, ";")]
493 ///
494 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
495 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
496 /// ```
497 #[stable(feature = "rust1", since = "1.0.0")]
498 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
499 #[must_use = "this returns the result of the operation, \
500 without modifying the original"]
501 #[inline(always)]
502 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
503 pub const fn rotate_right(self, n: u32) -> Self {
504 return intrinsics::rotate_right(self, n);
505 }
506
507 /// Performs a left funnel shift.
508 ///
509 /// This operation can be thought of as concatenating `self` and `right` into an
510 /// integer twice the size of
511 #[doc = concat!("`", stringify!($SelfT) , "`,")]
512 /// performing a left shift by `n`, and returning the **left half** of the result.
513 ///
514 /// The name comes from "funneling" a wider integer to a narrower integer.
515 ///
516 /// # Panics
517 ///
518 /// ## Overflow behavior
519 ///
520 /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
521 /// is greater than or equal to the number of bits in `self`. If overflow checks are
522 /// disabled (default in release mode), there is no panic; instead, the value is shifted
523 /// by `n % Self::BITS`.
524 // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shl` when stable.
525 ///
526 /// # Examples
527 ///
528 /// ```
529 /// #![feature(funnel_shifts)]
530 ///
531 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
532 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
533 ///
534 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), ", $fshl_result, ");")]
535 ///
536 /// // Using zeros as the right operand acts as a normal shift left
537 #[doc = concat!("assert_eq!(a.funnel_shl(0, ", $rot, "), a << ", $rot, ");")]
538 ///
539 /// // Shifting by 0 returns `self` unchanged
540 #[doc = concat!("assert_eq!(a.funnel_shl(b, 0), a);")]
541 ///
542 /// // Using the same value as the right operand acts as a rotate
543 #[doc = concat!("assert_eq!(a.funnel_shl(a, ", $rot, "), a.rotate_left(", $rot, "));")]
544 /// ```
545 ///
546 /// Note that while `funnel_shl` can act as a rotate, it does not allow for
547 /// rotating by an unbounded amount like [`rotate_left`](Self::rotate_left) does:
548 ///
549 /// ```should_panic
550 /// #![feature(funnel_shifts)]
551 /// # #![feature(cfg_overflow_checks)]
552 /// # #[cfg(overflow_checks)] {
553 ///
554 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
555 /// // Okay
556 #[doc = concat!("let _ = a.rotate_left(", stringify!($SelfT), "::BITS);")]
557 /// // Panics (only when overflow checks are enabled)
558 #[doc = concat!("let _ = a.funnel_shl(a, ", stringify!($SelfT), "::BITS);")]
559 /// # }
560 /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
561 /// ```
562 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
563 #[unstable(feature = "funnel_shifts", issue = "145686")]
564 #[must_use = "this returns the result of the operation, without modifying the original"]
565 #[inline(always)]
566 #[rustc_inherit_overflow_checks]
567 pub const fn funnel_shl(self, right: Self, n: u32) -> Self {
568 if intrinsics::overflow_checks() {
569 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
570 }
571 // SAFETY: `n` is wrapped to within range
572 unsafe {
573 let n = n & (Self::BITS - 1);
574 self.unchecked_funnel_shl(right, n)
575 }
576 }
577
578 /// Performs a right funnel shift.
579 ///
580 /// This operation can be thought of as concatenating `self` and `right` into an
581 /// integer twice the size of
582 #[doc = concat!("`", stringify!($SelfT) , "`,")]
583 /// performing a right shift by `n`, and returning the **right half** of the result.
584 ///
585 /// The name comes from "funneling" a wider integer to a narrower integer.
586 ///
587 /// # Panics
588 ///
589 /// ## Overflow behavior
590 ///
591 /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
592 /// is greater than or equal to the number of bits in `self`. If overflow checks are
593 /// disabled (default in release mode), there is no panic; instead, the value is shifted
594 /// by `n % Self::BITS`.
595 // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shr` when stable.
596 ///
597 /// # Examples
598 ///
599 /// ```
600 /// #![feature(funnel_shifts)]
601 ///
602 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
603 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
604 ///
605 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), ", $fshr_result, ");")]
606 ///
607 /// // Using zeros as the left operand acts as a normal shift right
608 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".funnel_shr(a, ", $rot, "), a >> ", $rot, ");")]
609 ///
610 /// // Shifting by 0 returns `right` unchanged
611 #[doc = concat!("assert_eq!(b.funnel_shr(a, 0), a);")]
612 ///
613 /// // Using the same value as the right operand acts as a rotate
614 #[doc = concat!("assert_eq!(a.funnel_shr(a, ", $rot, "), a.rotate_right(", $rot, "));")]
615 /// ```
616 ///
617 /// Note that while `funnel_shr` can act as a rotate, it does not allow for
618 /// rotating by an unbounded amount like [`rotate_right`](Self::rotate_right) does:
619 ///
620 /// ```should_panic
621 /// #![feature(funnel_shifts)]
622 /// # #![feature(cfg_overflow_checks)]
623 /// # #[cfg(overflow_checks)] {
624 ///
625 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
626 /// // Okay
627 #[doc = concat!("let _ = a.rotate_right(", stringify!($SelfT), "::BITS);")]
628 /// // Panics (only when overflow checks are enabled)
629 #[doc = concat!("let _ = a.funnel_shr(a, ", stringify!($SelfT), "::BITS);")]
630 /// # }
631 /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
632 /// ```
633 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
634 #[unstable(feature = "funnel_shifts", issue = "145686")]
635 #[must_use = "this returns the result of the operation, without modifying the original"]
636 #[inline(always)]
637 #[rustc_inherit_overflow_checks]
638 pub const fn funnel_shr(self, right: Self, n: u32) -> Self {
639 if intrinsics::overflow_checks() {
640 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
641 }
642 // SAFETY: `n` is wrapped to within range
643 unsafe {
644 let n = n & (Self::BITS - 1);
645 self.unchecked_funnel_shr(right, n)
646 }
647 }
648
649 /// Unchecked funnel shift left.
650 ///
651 /// # Safety
652 ///
653 /// This results in undefined behavior if `n` is greater than or equal to
654 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
655 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
656 ///
657 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
658 #[unstable(feature = "funnel_shifts", issue = "145686")]
659 #[must_use = "this returns the result of the operation, without modifying the original"]
660 #[inline(always)]
661 #[track_caller]
662 pub const unsafe fn unchecked_funnel_shl(self, right: Self, n: u32) -> Self {
663 assert_unsafe_precondition!(
664 check_language_ub,
665 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
666 (n: u32 = n) => n < <$ActualT>::BITS,
667 );
668
669 // SAFETY: this is guaranteed to be safe by the caller.
670 unsafe {
671 intrinsics::unchecked_funnel_shl(self, right, n)
672 }
673 }
674
675 /// Unchecked funnel shift right.
676 ///
677 /// # Safety
678 ///
679 /// This results in undefined behavior if `n` is greater than or equal to
680 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
681 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
682 ///
683 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
684 #[unstable(feature = "funnel_shifts", issue = "145686")]
685 #[must_use = "this returns the result of the operation, without modifying the original"]
686 #[inline(always)]
687 #[track_caller]
688 pub const unsafe fn unchecked_funnel_shr(self, right: Self, n: u32) -> Self {
689 assert_unsafe_precondition!(
690 check_language_ub,
691 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
692 (n: u32 = n) => n < <$ActualT>::BITS,
693 );
694
695 // SAFETY: this is guaranteed to be safe by the caller.
696 unsafe {
697 intrinsics::unchecked_funnel_shr(self, right, n)
698 }
699 }
700
701 /// Performs a carry-less multiplication, returning the lower bits.
702 ///
703 /// This operation is similar to long multiplication in base 2, except that exclusive or is
704 /// used instead of addition. The implementation is equivalent to:
705 ///
706 /// ```no_run
707 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
708 /// let mut retval = 0;
709 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
710 /// if (rhs >> i) & 1 != 0 {
711 /// // long multiplication would use +=
712 /// retval ^= lhs << i;
713 /// }
714 /// }
715 /// retval
716 /// }
717 /// ```
718 ///
719 /// The actual implementation is more efficient, and on some platforms lowers directly to a
720 /// dedicated instruction.
721 ///
722 /// # Uses
723 ///
724 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
725 /// bit mask of characters surrounded by quotes:
726 ///
727 /// ```no_run
728 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
729 /// 0b0000000010000001000001010; // quote_mask
730 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
731 /// ```
732 ///
733 /// Another use is in cryptography, where carryless multiplication allows for efficient
734 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
735 /// over `GF(2)`.
736 ///
737 /// # Examples
738 ///
739 /// ```
740 /// #![feature(uint_carryless_mul)]
741 ///
742 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
743 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
744 ///
745 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
746 /// ```
747 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
748 #[doc(alias = "clmul")]
749 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
750 #[must_use = "this returns the result of the operation, \
751 without modifying the original"]
752 #[inline(always)]
753 pub const fn carryless_mul(self, rhs: Self) -> Self {
754 intrinsics::carryless_mul(self, rhs)
755 }
756
757 /// Reverses the byte order of the integer.
758 ///
759 /// # Examples
760 ///
761 /// ```
762 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
763 /// let m = n.swap_bytes();
764 ///
765 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
766 /// ```
767 #[stable(feature = "rust1", since = "1.0.0")]
768 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
769 #[must_use = "this returns the result of the operation, \
770 without modifying the original"]
771 #[inline(always)]
772 pub const fn swap_bytes(self) -> Self {
773 intrinsics::bswap(self as $ActualT) as Self
774 }
775
776 /// Returns an integer with the bit locations specified by `mask` packed
777 /// contiguously into the least significant bits of the result.
778 /// ```
779 /// #![feature(uint_gather_scatter_bits)]
780 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
781 ///
782 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
783 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
784 /// ```
785 #[doc(alias = "pext")]
786 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
787 #[must_use = "this returns the result of the operation, \
788 without modifying the original"]
789 #[inline]
790 pub const fn extract_bits(self, mask: Self) -> Self {
791 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
792 }
793
794 /// Returns an integer with the least significant bits of `self`
795 /// distributed to the bit locations specified by `mask`.
796 /// ```
797 /// #![feature(uint_gather_scatter_bits)]
798 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
799 ///
800 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
801 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
802 /// ```
803 #[doc(alias = "pdep")]
804 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
805 #[must_use = "this returns the result of the operation, \
806 without modifying the original"]
807 #[inline]
808 pub const fn deposit_bits(self, mask: Self) -> Self {
809 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
810 }
811
812 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
813 /// second least-significant bit becomes second most-significant bit, etc.
814 ///
815 /// # Examples
816 ///
817 /// ```
818 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
819 /// let m = n.reverse_bits();
820 ///
821 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
822 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
823 /// ```
824 #[stable(feature = "reverse_bits", since = "1.37.0")]
825 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
826 #[must_use = "this returns the result of the operation, \
827 without modifying the original"]
828 #[inline(always)]
829 pub const fn reverse_bits(self) -> Self {
830 intrinsics::bitreverse(self as $ActualT) as Self
831 }
832
833 /// Converts an integer from big endian to the target's endianness.
834 ///
835 /// On big endian this is a no-op. On little endian the bytes are
836 /// swapped.
837 ///
838 /// # Examples
839 ///
840 /// ```
841 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
842 ///
843 /// if cfg!(target_endian = "big") {
844 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
845 /// } else {
846 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
847 /// }
848 /// ```
849 #[stable(feature = "rust1", since = "1.0.0")]
850 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
851 #[must_use]
852 #[inline(always)]
853 pub const fn from_be(x: Self) -> Self {
854 cfg_select! {
855 target_endian = "big" => x,
856 _ => x.swap_bytes(),
857 }
858 }
859
860 /// Converts an integer from little endian to the target's endianness.
861 ///
862 /// On little endian this is a no-op. On big endian the bytes are
863 /// swapped.
864 ///
865 /// # Examples
866 ///
867 /// ```
868 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
869 ///
870 /// if cfg!(target_endian = "little") {
871 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
872 /// } else {
873 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
874 /// }
875 /// ```
876 #[stable(feature = "rust1", since = "1.0.0")]
877 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
878 #[must_use]
879 #[inline(always)]
880 pub const fn from_le(x: Self) -> Self {
881 cfg_select! {
882 target_endian = "little" => x,
883 _ => x.swap_bytes(),
884 }
885 }
886
887 /// Converts `self` to big endian from the target's endianness.
888 ///
889 /// On big endian this is a no-op. On little endian the bytes are
890 /// swapped.
891 ///
892 /// # Examples
893 ///
894 /// ```
895 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
896 ///
897 /// if cfg!(target_endian = "big") {
898 /// assert_eq!(n.to_be(), n)
899 /// } else {
900 /// assert_eq!(n.to_be(), n.swap_bytes())
901 /// }
902 /// ```
903 #[stable(feature = "rust1", since = "1.0.0")]
904 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
905 #[must_use = "this returns the result of the operation, \
906 without modifying the original"]
907 #[inline(always)]
908 pub const fn to_be(self) -> Self { // or not to be?
909 cfg_select! {
910 target_endian = "big" => self,
911 _ => self.swap_bytes(),
912 }
913 }
914
915 /// Converts `self` to little endian from the target's endianness.
916 ///
917 /// On little endian this is a no-op. On big endian the bytes are
918 /// swapped.
919 ///
920 /// # Examples
921 ///
922 /// ```
923 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
924 ///
925 /// if cfg!(target_endian = "little") {
926 /// assert_eq!(n.to_le(), n)
927 /// } else {
928 /// assert_eq!(n.to_le(), n.swap_bytes())
929 /// }
930 /// ```
931 #[stable(feature = "rust1", since = "1.0.0")]
932 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
933 #[must_use = "this returns the result of the operation, \
934 without modifying the original"]
935 #[inline(always)]
936 pub const fn to_le(self) -> Self {
937 cfg_select! {
938 target_endian = "little" => self,
939 _ => self.swap_bytes(),
940 }
941 }
942
943 /// Checked integer addition. Computes `self + rhs`, returning `None`
944 /// if overflow occurred.
945 ///
946 /// # Examples
947 ///
948 /// ```
949 #[doc = concat!(
950 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
951 "Some(", stringify!($SelfT), "::MAX - 1));"
952 )]
953 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
954 /// ```
955 #[stable(feature = "rust1", since = "1.0.0")]
956 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
957 #[must_use = "this returns the result of the operation, \
958 without modifying the original"]
959 #[inline]
960 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
961 // This used to use `overflowing_add`, but that means it ends up being
962 // a `wrapping_add`, losing some optimization opportunities. Notably,
963 // phrasing it this way helps `.checked_add(1)` optimize to a check
964 // against `MAX` and a `add nuw`.
965 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
966 // LLVM is happy to re-form the intrinsic later if useful.
967
968 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
969 None
970 } else {
971 // SAFETY: Just checked it doesn't overflow
972 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
973 }
974 }
975
976 /// Strict integer addition. Computes `self + rhs`, panicking
977 /// if overflow occurred.
978 ///
979 /// # Panics
980 ///
981 /// ## Overflow behavior
982 ///
983 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
984 ///
985 /// # Examples
986 ///
987 /// ```
988 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
989 /// ```
990 ///
991 /// The following panics because of overflow:
992 ///
993 /// ```should_panic
994 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
995 /// ```
996 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
997 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
998 #[must_use = "this returns the result of the operation, \
999 without modifying the original"]
1000 #[inline]
1001 #[track_caller]
1002 pub const fn strict_add(self, rhs: Self) -> Self {
1003 let (a, b) = self.overflowing_add(rhs);
1004 if b { imp::overflow_panic::add() } else { a }
1005 }
1006
1007 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
1008 /// cannot occur.
1009 ///
1010 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
1011 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
1012 ///
1013 /// If you're just trying to avoid the panic in debug mode, then **do not**
1014 /// use this. Instead, you're looking for [`wrapping_add`].
1015 ///
1016 /// # Safety
1017 ///
1018 /// This results in undefined behavior when
1019 #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX`,")]
1020 /// i.e. when [`checked_add`] would return `None`.
1021 ///
1022 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1023 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
1024 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
1025 #[stable(feature = "unchecked_math", since = "1.79.0")]
1026 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1027 #[must_use = "this returns the result of the operation, \
1028 without modifying the original"]
1029 #[inline(always)]
1030 #[track_caller]
1031 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
1032 assert_unsafe_precondition!(
1033 check_language_ub,
1034 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
1035 (
1036 lhs: $SelfT = self,
1037 rhs: $SelfT = rhs,
1038 ) => !lhs.overflowing_add(rhs).1,
1039 );
1040
1041 // SAFETY: this is guaranteed to be safe by the caller.
1042 unsafe {
1043 intrinsics::unchecked_add(self, rhs)
1044 }
1045 }
1046
1047 /// Checked addition with a signed integer. Computes `self + rhs`,
1048 /// returning `None` if overflow occurred.
1049 ///
1050 /// # Examples
1051 ///
1052 /// ```
1053 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
1054 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
1055 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
1056 /// ```
1057 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
1058 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
1059 #[must_use = "this returns the result of the operation, \
1060 without modifying the original"]
1061 #[inline]
1062 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
1063 let (a, b) = self.overflowing_add_signed(rhs);
1064 if intrinsics::unlikely(b) { None } else { Some(a) }
1065 }
1066
1067 /// Strict addition with a signed integer. Computes `self + rhs`,
1068 /// panicking if overflow occurred.
1069 ///
1070 /// # Panics
1071 ///
1072 /// ## Overflow behavior
1073 ///
1074 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1075 ///
1076 /// # Examples
1077 ///
1078 /// ```
1079 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
1080 /// ```
1081 ///
1082 /// The following panic because of overflow:
1083 ///
1084 /// ```should_panic
1085 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
1086 /// ```
1087 ///
1088 /// ```should_panic
1089 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
1090 /// ```
1091 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1092 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1093 #[must_use = "this returns the result of the operation, \
1094 without modifying the original"]
1095 #[inline]
1096 #[track_caller]
1097 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
1098 let (a, b) = self.overflowing_add_signed(rhs);
1099 if b { imp::overflow_panic::add() } else { a }
1100 }
1101
1102 /// Checked integer subtraction. Computes `self - rhs`, returning
1103 /// `None` if overflow occurred.
1104 ///
1105 /// # Examples
1106 ///
1107 /// ```
1108 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
1109 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
1110 /// ```
1111 #[stable(feature = "rust1", since = "1.0.0")]
1112 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1113 #[must_use = "this returns the result of the operation, \
1114 without modifying the original"]
1115 #[inline]
1116 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
1117 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
1118 // for *unsigned* subtraction and we just emit the manual check anyway.
1119 // Thus, rather than using `overflowing_sub` that produces a wrapping
1120 // subtraction, check it ourself so we can use an unchecked one.
1121
1122 if self < rhs {
1123 None
1124 } else {
1125 // SAFETY: just checked this can't overflow
1126 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
1127 }
1128 }
1129
1130 /// Strict integer subtraction. Computes `self - rhs`, panicking if
1131 /// overflow occurred.
1132 ///
1133 /// # Panics
1134 ///
1135 /// ## Overflow behavior
1136 ///
1137 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1138 ///
1139 /// # Examples
1140 ///
1141 /// ```
1142 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
1143 /// ```
1144 ///
1145 /// The following panics because of overflow:
1146 ///
1147 /// ```should_panic
1148 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1149 /// ```
1150 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1151 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1152 #[must_use = "this returns the result of the operation, \
1153 without modifying the original"]
1154 #[inline]
1155 #[track_caller]
1156 pub const fn strict_sub(self, rhs: Self) -> Self {
1157 let (a, b) = self.overflowing_sub(rhs);
1158 if b { imp::overflow_panic::sub() } else { a }
1159 }
1160
1161 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1162 /// cannot occur.
1163 ///
1164 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1165 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1166 ///
1167 /// If you're just trying to avoid the panic in debug mode, then **do not**
1168 /// use this. Instead, you're looking for [`wrapping_sub`].
1169 ///
1170 /// If you find yourself writing code like this:
1171 ///
1172 /// ```
1173 /// # let foo = 30_u32;
1174 /// # let bar = 20;
1175 /// if foo >= bar {
1176 /// // SAFETY: just checked it will not overflow
1177 /// let diff = unsafe { foo.unchecked_sub(bar) };
1178 /// // ... use diff ...
1179 /// }
1180 /// ```
1181 ///
1182 /// Consider changing it to
1183 ///
1184 /// ```
1185 /// # let foo = 30_u32;
1186 /// # let bar = 20;
1187 /// if let Some(diff) = foo.checked_sub(bar) {
1188 /// // ... use diff ...
1189 /// }
1190 /// ```
1191 ///
1192 /// As that does exactly the same thing -- including telling the optimizer
1193 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1194 ///
1195 /// # Safety
1196 ///
1197 /// This results in undefined behavior when
1198 #[doc = concat!("`self - rhs < ", stringify!($SelfT), "::MIN`,")]
1199 /// i.e. when [`checked_sub`] would return `None`.
1200 ///
1201 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1202 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1203 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1204 #[stable(feature = "unchecked_math", since = "1.79.0")]
1205 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1206 #[must_use = "this returns the result of the operation, \
1207 without modifying the original"]
1208 #[inline(always)]
1209 #[track_caller]
1210 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1211 assert_unsafe_precondition!(
1212 check_language_ub,
1213 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1214 (
1215 lhs: $SelfT = self,
1216 rhs: $SelfT = rhs,
1217 ) => !lhs.overflowing_sub(rhs).1,
1218 );
1219
1220 // SAFETY: this is guaranteed to be safe by the caller.
1221 unsafe {
1222 intrinsics::unchecked_sub(self, rhs)
1223 }
1224 }
1225
1226 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1227 /// returning `None` if overflow occurred.
1228 ///
1229 /// # Examples
1230 ///
1231 /// ```
1232 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1233 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1234 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1235 /// ```
1236 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1237 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1238 #[must_use = "this returns the result of the operation, \
1239 without modifying the original"]
1240 #[inline]
1241 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1242 let (res, overflow) = self.overflowing_sub_signed(rhs);
1243
1244 if !overflow {
1245 Some(res)
1246 } else {
1247 None
1248 }
1249 }
1250
1251 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1252 /// panicking if overflow occurred.
1253 ///
1254 /// # Panics
1255 ///
1256 /// ## Overflow behavior
1257 ///
1258 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1259 ///
1260 /// # Examples
1261 ///
1262 /// ```
1263 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1264 /// ```
1265 ///
1266 /// The following panic because of overflow:
1267 ///
1268 /// ```should_panic
1269 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1270 /// ```
1271 ///
1272 /// ```should_panic
1273 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1274 /// ```
1275 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1276 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1277 #[must_use = "this returns the result of the operation, \
1278 without modifying the original"]
1279 #[inline]
1280 #[track_caller]
1281 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1282 let (a, b) = self.overflowing_sub_signed(rhs);
1283 if b { imp::overflow_panic::sub() } else { a }
1284 }
1285
1286 #[doc = concat!(
1287 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1288 stringify!($SignedT), "`], returning `None` if overflow occurred."
1289 )]
1290 ///
1291 /// # Examples
1292 ///
1293 /// ```
1294 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1295 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1296 #[doc = concat!(
1297 "assert_eq!(",
1298 stringify!($SelfT),
1299 "::MAX.checked_signed_diff(",
1300 stringify!($SignedT),
1301 "::MAX as ",
1302 stringify!($SelfT),
1303 "), None);"
1304 )]
1305 #[doc = concat!(
1306 "assert_eq!((",
1307 stringify!($SignedT),
1308 "::MAX as ",
1309 stringify!($SelfT),
1310 ").checked_signed_diff(",
1311 stringify!($SelfT),
1312 "::MAX), Some(",
1313 stringify!($SignedT),
1314 "::MIN));"
1315 )]
1316 #[doc = concat!(
1317 "assert_eq!((",
1318 stringify!($SignedT),
1319 "::MAX as ",
1320 stringify!($SelfT),
1321 " + 1).checked_signed_diff(0), None);"
1322 )]
1323 #[doc = concat!(
1324 "assert_eq!(",
1325 stringify!($SelfT),
1326 "::MAX.checked_signed_diff(",
1327 stringify!($SelfT),
1328 "::MAX), Some(0));"
1329 )]
1330 /// ```
1331 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1332 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1333 #[inline]
1334 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1335 let res = self.wrapping_sub(rhs) as $SignedT;
1336 let overflow = (self >= rhs) == (res < 0);
1337
1338 if !overflow {
1339 Some(res)
1340 } else {
1341 None
1342 }
1343 }
1344
1345 /// Checked integer multiplication. Computes `self * rhs`, returning
1346 /// `None` if overflow occurred.
1347 ///
1348 /// # Examples
1349 ///
1350 /// ```
1351 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1352 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1353 /// ```
1354 #[stable(feature = "rust1", since = "1.0.0")]
1355 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1356 #[must_use = "this returns the result of the operation, \
1357 without modifying the original"]
1358 #[inline]
1359 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1360 let (a, b) = self.overflowing_mul(rhs);
1361 if intrinsics::unlikely(b) { None } else { Some(a) }
1362 }
1363
1364 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1365 /// overflow occurred.
1366 ///
1367 /// # Panics
1368 ///
1369 /// ## Overflow behavior
1370 ///
1371 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1372 ///
1373 /// # Examples
1374 ///
1375 /// ```
1376 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1377 /// ```
1378 ///
1379 /// The following panics because of overflow:
1380 ///
1381 /// ``` should_panic
1382 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1383 /// ```
1384 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1385 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1386 #[must_use = "this returns the result of the operation, \
1387 without modifying the original"]
1388 #[inline]
1389 #[track_caller]
1390 pub const fn strict_mul(self, rhs: Self) -> Self {
1391 let (a, b) = self.overflowing_mul(rhs);
1392 if b { imp::overflow_panic::mul() } else { a }
1393 }
1394
1395 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1396 /// cannot occur.
1397 ///
1398 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1399 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1400 ///
1401 /// If you're just trying to avoid the panic in debug mode, then **do not**
1402 /// use this. Instead, you're looking for [`wrapping_mul`].
1403 ///
1404 /// # Safety
1405 ///
1406 /// This results in undefined behavior when
1407 #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX`,")]
1408 /// i.e. when [`checked_mul`] would return `None`.
1409 ///
1410 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1411 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1412 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1413 #[stable(feature = "unchecked_math", since = "1.79.0")]
1414 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1415 #[must_use = "this returns the result of the operation, \
1416 without modifying the original"]
1417 #[inline(always)]
1418 #[track_caller]
1419 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1420 assert_unsafe_precondition!(
1421 check_language_ub,
1422 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1423 (
1424 lhs: $SelfT = self,
1425 rhs: $SelfT = rhs,
1426 ) => !lhs.overflowing_mul(rhs).1,
1427 );
1428
1429 // SAFETY: this is guaranteed to be safe by the caller.
1430 unsafe {
1431 intrinsics::unchecked_mul(self, rhs)
1432 }
1433 }
1434
1435 /// Checked integer division. Computes `self / rhs`, returning `None`
1436 /// if `rhs == 0`.
1437 ///
1438 /// # Examples
1439 ///
1440 /// ```
1441 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1442 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1443 /// ```
1444 #[stable(feature = "rust1", since = "1.0.0")]
1445 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1446 #[must_use = "this returns the result of the operation, \
1447 without modifying the original"]
1448 #[inline]
1449 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1450 if intrinsics::unlikely(rhs == 0) {
1451 None
1452 } else {
1453 // SAFETY: div by zero has been checked above and unsigned types have no other
1454 // failure modes for division
1455 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1456 }
1457 }
1458
1459 /// Strict integer division. Computes `self / rhs`.
1460 ///
1461 /// Strict division on unsigned types is just normal division. There's no
1462 /// way overflow could ever happen. This function exists so that all
1463 /// operations are accounted for in the strict operations.
1464 ///
1465 /// # Panics
1466 ///
1467 /// This function will panic if `rhs` is zero.
1468 ///
1469 /// # Examples
1470 ///
1471 /// ```
1472 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1473 /// ```
1474 ///
1475 /// The following panics because of division by zero:
1476 ///
1477 /// ```should_panic
1478 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1479 /// ```
1480 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1481 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1482 #[must_use = "this returns the result of the operation, \
1483 without modifying the original"]
1484 #[inline(always)]
1485 #[track_caller]
1486 pub const fn strict_div(self, rhs: Self) -> Self {
1487 self / rhs
1488 }
1489
1490 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1491 /// if `rhs == 0`.
1492 ///
1493 /// # Examples
1494 ///
1495 /// ```
1496 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1497 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1498 /// ```
1499 #[stable(feature = "euclidean_division", since = "1.38.0")]
1500 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1501 #[must_use = "this returns the result of the operation, \
1502 without modifying the original"]
1503 #[inline]
1504 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1505 if intrinsics::unlikely(rhs == 0) {
1506 None
1507 } else {
1508 Some(self.div_euclid(rhs))
1509 }
1510 }
1511
1512 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1513 ///
1514 /// Strict division on unsigned types is just normal division. There's no
1515 /// way overflow could ever happen. This function exists so that all
1516 /// operations are accounted for in the strict operations. Since, for the
1517 /// positive integers, all common definitions of division are equal, this
1518 /// is exactly equal to `self.strict_div(rhs)`.
1519 ///
1520 /// # Panics
1521 ///
1522 /// This function will panic if `rhs` is zero.
1523 ///
1524 /// # Examples
1525 ///
1526 /// ```
1527 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1528 /// ```
1529 /// The following panics because of division by zero:
1530 ///
1531 /// ```should_panic
1532 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1533 /// ```
1534 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1535 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1536 #[must_use = "this returns the result of the operation, \
1537 without modifying the original"]
1538 #[inline(always)]
1539 #[track_caller]
1540 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1541 self / rhs
1542 }
1543
1544 /// Checked integer division without remainder. Computes `self / rhs`,
1545 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1546 ///
1547 /// # Examples
1548 ///
1549 /// ```
1550 /// #![feature(exact_div)]
1551 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1552 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1553 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1554 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1555 /// ```
1556 #[unstable(
1557 feature = "exact_div",
1558 issue = "139911",
1559 )]
1560 #[must_use = "this returns the result of the operation, \
1561 without modifying the original"]
1562 #[inline]
1563 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1564 if intrinsics::unlikely(rhs == 0) {
1565 None
1566 } else {
1567 // SAFETY: division by zero is checked above
1568 unsafe {
1569 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1570 None
1571 } else {
1572 Some(intrinsics::exact_div(self, rhs))
1573 }
1574 }
1575 }
1576 }
1577
1578 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1579 ///
1580 /// # Panics
1581 ///
1582 /// This function will panic if `rhs == 0`.
1583 ///
1584 /// # Examples
1585 ///
1586 /// ```
1587 /// #![feature(exact_div)]
1588 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1589 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1590 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1591 /// ```
1592 #[unstable(
1593 feature = "exact_div",
1594 issue = "139911",
1595 )]
1596 #[must_use = "this returns the result of the operation, \
1597 without modifying the original"]
1598 #[inline]
1599 #[rustc_inherit_overflow_checks]
1600 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1601 if self % rhs != 0 {
1602 None
1603 } else {
1604 Some(self / rhs)
1605 }
1606 }
1607
1608 /// Unchecked integer division without remainder. Computes `self / rhs`.
1609 ///
1610 /// # Safety
1611 ///
1612 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1613 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1614 #[unstable(
1615 feature = "exact_div",
1616 issue = "139911",
1617 )]
1618 #[must_use = "this returns the result of the operation, \
1619 without modifying the original"]
1620 #[inline]
1621 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1622 assert_unsafe_precondition!(
1623 check_language_ub,
1624 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1625 (
1626 lhs: $SelfT = self,
1627 rhs: $SelfT = rhs,
1628 ) => rhs > 0 && lhs % rhs == 0,
1629 );
1630 // SAFETY: Same precondition
1631 unsafe { intrinsics::exact_div(self, rhs) }
1632 }
1633
1634 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1635 /// if `rhs == 0`.
1636 ///
1637 /// # Examples
1638 ///
1639 /// ```
1640 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1641 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1642 /// ```
1643 #[stable(feature = "wrapping", since = "1.7.0")]
1644 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1645 #[must_use = "this returns the result of the operation, \
1646 without modifying the original"]
1647 #[inline]
1648 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1649 if intrinsics::unlikely(rhs == 0) {
1650 None
1651 } else {
1652 // SAFETY: div by zero has been checked above and unsigned types have no other
1653 // failure modes for division
1654 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1655 }
1656 }
1657
1658 /// Strict integer remainder. Computes `self % rhs`.
1659 ///
1660 /// Strict remainder calculation on unsigned types is just the regular
1661 /// remainder calculation. There's no way overflow could ever happen.
1662 /// This function exists so that all operations are accounted for in the
1663 /// strict operations.
1664 ///
1665 /// # Panics
1666 ///
1667 /// This function will panic if `rhs` is zero.
1668 ///
1669 /// # Examples
1670 ///
1671 /// ```
1672 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1673 /// ```
1674 ///
1675 /// The following panics because of division by zero:
1676 ///
1677 /// ```should_panic
1678 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1679 /// ```
1680 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1681 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1682 #[must_use = "this returns the result of the operation, \
1683 without modifying the original"]
1684 #[inline(always)]
1685 #[track_caller]
1686 pub const fn strict_rem(self, rhs: Self) -> Self {
1687 self % rhs
1688 }
1689
1690 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1691 /// if `rhs == 0`.
1692 ///
1693 /// # Examples
1694 ///
1695 /// ```
1696 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1697 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1698 /// ```
1699 #[stable(feature = "euclidean_division", since = "1.38.0")]
1700 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1701 #[must_use = "this returns the result of the operation, \
1702 without modifying the original"]
1703 #[inline]
1704 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1705 if intrinsics::unlikely(rhs == 0) {
1706 None
1707 } else {
1708 Some(self.rem_euclid(rhs))
1709 }
1710 }
1711
1712 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1713 ///
1714 /// Strict modulo calculation on unsigned types is just the regular
1715 /// remainder calculation. There's no way overflow could ever happen.
1716 /// This function exists so that all operations are accounted for in the
1717 /// strict operations. Since, for the positive integers, all common
1718 /// definitions of division are equal, this is exactly equal to
1719 /// `self.strict_rem(rhs)`.
1720 ///
1721 /// # Panics
1722 ///
1723 /// This function will panic if `rhs` is zero.
1724 ///
1725 /// # Examples
1726 ///
1727 /// ```
1728 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1729 /// ```
1730 ///
1731 /// The following panics because of division by zero:
1732 ///
1733 /// ```should_panic
1734 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1735 /// ```
1736 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1737 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1738 #[must_use = "this returns the result of the operation, \
1739 without modifying the original"]
1740 #[inline(always)]
1741 #[track_caller]
1742 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1743 self % rhs
1744 }
1745
1746 /// Same value as `self | other`, but UB if any bit position is set in both inputs.
1747 ///
1748 /// This is a situational micro-optimization for places where you'd rather
1749 /// use addition on some platforms and bitwise or on other platforms, based
1750 /// on exactly which instructions combine better with whatever else you're
1751 /// doing. Note that there's no reason to bother using this for places
1752 /// where it's clear from the operations involved that they can't overlap.
1753 /// For example, if you're combining `u16`s into a `u32` with
1754 /// `((a as u32) << 16) | (b as u32)`, that's fine, as the backend will
1755 /// know those sides of the `|` are disjoint without needing help.
1756 ///
1757 /// # Examples
1758 ///
1759 /// ```
1760 /// #![feature(disjoint_bitor)]
1761 ///
1762 /// // SAFETY: `1` and `4` have no bits in common.
1763 /// unsafe {
1764 #[doc = concat!(" assert_eq!(1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4), 5);")]
1765 /// }
1766 /// ```
1767 ///
1768 /// # Safety
1769 ///
1770 /// Requires that `(self & other) == 0`, otherwise it's immediate UB.
1771 ///
1772 /// Equivalently, requires that `(self | other) == (self + other)`.
1773 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1774 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1775 #[inline]
1776 pub const unsafe fn unchecked_disjoint_bitor(self, other: Self) -> Self {
1777 assert_unsafe_precondition!(
1778 check_language_ub,
1779 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot have overlapping bits"),
1780 (
1781 lhs: $SelfT = self,
1782 rhs: $SelfT = other,
1783 ) => (lhs & rhs) == 0,
1784 );
1785
1786 // SAFETY: Same precondition
1787 unsafe { intrinsics::disjoint_bitor(self, other) }
1788 }
1789
1790 /// Returns the logarithm of the number with respect to an arbitrary base,
1791 /// rounded down.
1792 ///
1793 /// This method might not be optimized owing to implementation details;
1794 /// [`ilog2`](Self::ilog2) can produce results more efficiently for base 2,
1795 /// and [`ilog10`](Self::ilog10) can produce results more efficiently for base 10.
1796 ///
1797 /// # Panics
1798 ///
1799 /// This function will panic if `self` is zero, or if `base` is less than 2.
1800 ///
1801 /// # Examples
1802 ///
1803 /// ```
1804 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1805 /// ```
1806 #[stable(feature = "int_log", since = "1.67.0")]
1807 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1808 #[must_use = "this returns the result of the operation, \
1809 without modifying the original"]
1810 #[inline]
1811 #[track_caller]
1812 pub const fn ilog(self, base: Self) -> u32 {
1813 assert!(base >= 2, "base of integer logarithm must be at least 2");
1814 if let Some(log) = self.checked_ilog(base) {
1815 log
1816 } else {
1817 imp::int_log10::panic_for_nonpositive_argument()
1818 }
1819 }
1820
1821 /// Returns the base 2 logarithm of the number, rounded down.
1822 ///
1823 /// # Panics
1824 ///
1825 /// This function will panic if `self` is zero.
1826 ///
1827 /// # Examples
1828 ///
1829 /// ```
1830 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1831 /// ```
1832 #[stable(feature = "int_log", since = "1.67.0")]
1833 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1834 #[must_use = "this returns the result of the operation, \
1835 without modifying the original"]
1836 #[inline]
1837 #[track_caller]
1838 pub const fn ilog2(self) -> u32 {
1839 if let Some(log) = self.checked_ilog2() {
1840 log
1841 } else {
1842 imp::int_log10::panic_for_nonpositive_argument()
1843 }
1844 }
1845
1846 /// Returns the base 10 logarithm of the number, rounded down.
1847 ///
1848 /// # Panics
1849 ///
1850 /// This function will panic if `self` is zero.
1851 ///
1852 /// # Example
1853 ///
1854 /// ```
1855 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1856 /// ```
1857 #[stable(feature = "int_log", since = "1.67.0")]
1858 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1859 #[must_use = "this returns the result of the operation, \
1860 without modifying the original"]
1861 #[inline]
1862 #[track_caller]
1863 pub const fn ilog10(self) -> u32 {
1864 if let Some(log) = self.checked_ilog10() {
1865 log
1866 } else {
1867 imp::int_log10::panic_for_nonpositive_argument()
1868 }
1869 }
1870
1871 /// Returns the logarithm of the number with respect to an arbitrary base,
1872 /// rounded down.
1873 ///
1874 /// Returns `None` if the number is zero, or if the base is not at least 2.
1875 ///
1876 /// This method might not be optimized owing to implementation details;
1877 /// `checked_ilog2` can produce results more efficiently for base 2, and
1878 /// `checked_ilog10` can produce results more efficiently for base 10.
1879 ///
1880 /// # Examples
1881 ///
1882 /// ```
1883 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1884 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".checked_ilog(5), Some(0));")]
1885 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(0), None);")]
1886 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(1), None);")]
1887 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_ilog(1), None);")]
1888 /// ```
1889 #[stable(feature = "int_log", since = "1.67.0")]
1890 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1891 #[must_use = "this returns the result of the operation, \
1892 without modifying the original"]
1893 #[inline]
1894 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1895 // Inform compiler of optimizations when the base is known at
1896 // compile time and there's a cheaper method available.
1897 //
1898 // Note: Like all optimizations, this is not guaranteed to be
1899 // applied by the compiler. If you want those specific bases,
1900 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1901 if core::intrinsics::is_val_statically_known(base) {
1902 // change of base:
1903 // if base == 2 ** k, then
1904 // log(base, n) == log(2, n) / k
1905 if base.is_power_of_two() && base > 1 {
1906 let k = base.ilog2();
1907 return Some(try_opt!(self.checked_ilog2()) / k);
1908 }
1909 if base == 10 {
1910 return self.checked_ilog10();
1911 }
1912 }
1913
1914 if self <= 0 || base <= 1 {
1915 None
1916 } else if self < base {
1917 Some(0)
1918 } else {
1919 // Since base >= self, n >= 1
1920 let mut n = 1;
1921 let mut r = base;
1922
1923 // Optimization for 128 bit wide integers.
1924 if Self::BITS == 128 {
1925 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1926 //
1927 // log(base,self) = log(2,self) / log(2,base)
1928 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1929 //
1930 // hence
1931 //
1932 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1933 n = self.ilog2() / (base.ilog2() + 1);
1934 r = base.pow(n);
1935 }
1936
1937 while r <= self / base {
1938 n += 1;
1939 r *= base;
1940 }
1941 Some(n)
1942 }
1943 }
1944
1945 /// Returns the base 2 logarithm of the number, rounded down.
1946 ///
1947 /// Returns `None` if the number is zero.
1948 ///
1949 /// Note that this is equivalent to [`highest_one`](Self::highest_one).
1950 ///
1951 /// # Examples
1952 ///
1953 /// ```
1954 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1955 /// ```
1956 #[stable(feature = "int_log", since = "1.67.0")]
1957 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1958 #[must_use = "this returns the result of the operation, \
1959 without modifying the original"]
1960 #[inline]
1961 pub const fn checked_ilog2(self) -> Option<u32> {
1962 match NonZero::new(self) {
1963 Some(x) => Some(x.ilog2()),
1964 None => None,
1965 }
1966 }
1967
1968 /// Returns the base 10 logarithm of the number, rounded down.
1969 ///
1970 /// Returns `None` if the number is zero.
1971 ///
1972 /// # Examples
1973 ///
1974 /// ```
1975 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1976 /// ```
1977 #[stable(feature = "int_log", since = "1.67.0")]
1978 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1979 #[must_use = "this returns the result of the operation, \
1980 without modifying the original"]
1981 #[inline]
1982 pub const fn checked_ilog10(self) -> Option<u32> {
1983 match NonZero::new(self) {
1984 Some(x) => Some(x.ilog10()),
1985 None => None,
1986 }
1987 }
1988
1989 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1990 /// 0`.
1991 ///
1992 /// Note that negating any positive integer will overflow.
1993 ///
1994 /// # Examples
1995 ///
1996 /// ```
1997 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1998 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1999 /// ```
2000 #[stable(feature = "wrapping", since = "1.7.0")]
2001 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2002 #[must_use = "this returns the result of the operation, \
2003 without modifying the original"]
2004 #[inline]
2005 pub const fn checked_neg(self) -> Option<Self> {
2006 let (a, b) = self.overflowing_neg();
2007 if intrinsics::unlikely(b) { None } else { Some(a) }
2008 }
2009
2010 /// Strict negation. Computes `-self`, panicking unless `self ==
2011 /// 0`.
2012 ///
2013 /// Note that negating any positive integer will overflow.
2014 ///
2015 /// # Panics
2016 ///
2017 /// ## Overflow behavior
2018 ///
2019 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2020 ///
2021 /// # Examples
2022 ///
2023 /// ```
2024 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
2025 /// ```
2026 ///
2027 /// The following panics because of overflow:
2028 ///
2029 /// ```should_panic
2030 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
2031 /// ```
2032 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2033 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2034 #[must_use = "this returns the result of the operation, \
2035 without modifying the original"]
2036 #[inline]
2037 #[track_caller]
2038 pub const fn strict_neg(self) -> Self {
2039 let (a, b) = self.overflowing_neg();
2040 if b { imp::overflow_panic::neg() } else { a }
2041 }
2042
2043 /// Checked shift left. Computes `self << rhs`, returning `None`
2044 /// if `rhs` is larger than or equal to the number of bits in `self`.
2045 ///
2046 /// # Examples
2047 ///
2048 /// ```
2049 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
2050 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
2051 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
2052 /// ```
2053 #[stable(feature = "wrapping", since = "1.7.0")]
2054 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2055 #[must_use = "this returns the result of the operation, \
2056 without modifying the original"]
2057 #[inline]
2058 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
2059 // Not using overflowing_shl as that's a wrapping shift
2060 if rhs < Self::BITS {
2061 // SAFETY: just checked the RHS is in-range
2062 Some(unsafe { self.unchecked_shl(rhs) })
2063 } else {
2064 None
2065 }
2066 }
2067
2068 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
2069 /// than or equal to the number of bits in `self`.
2070 ///
2071 /// # Panics
2072 ///
2073 /// ## Overflow behavior
2074 ///
2075 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2076 ///
2077 /// # Examples
2078 ///
2079 /// ```
2080 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
2081 /// ```
2082 ///
2083 /// The following panics because of overflow:
2084 ///
2085 /// ```should_panic
2086 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
2087 /// ```
2088 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2089 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2090 #[must_use = "this returns the result of the operation, \
2091 without modifying the original"]
2092 #[inline]
2093 #[track_caller]
2094 pub const fn strict_shl(self, rhs: u32) -> Self {
2095 let (a, b) = self.overflowing_shl(rhs);
2096 if b { imp::overflow_panic::shl() } else { a }
2097 }
2098
2099 /// Unchecked shift left. Computes `self << rhs`, assuming that
2100 /// `rhs` is less than the number of bits in `self`.
2101 ///
2102 /// # Safety
2103 ///
2104 /// This results in undefined behavior if `rhs` is larger than
2105 /// or equal to the number of bits in `self`,
2106 /// i.e. when [`checked_shl`] would return `None`.
2107 ///
2108 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
2109 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2110 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2111 #[must_use = "this returns the result of the operation, \
2112 without modifying the original"]
2113 #[inline(always)]
2114 #[track_caller]
2115 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
2116 assert_unsafe_precondition!(
2117 check_language_ub,
2118 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
2119 (
2120 rhs: u32 = rhs,
2121 ) => rhs < <$ActualT>::BITS,
2122 );
2123
2124 // SAFETY: this is guaranteed to be safe by the caller.
2125 unsafe {
2126 intrinsics::unchecked_shl(self, rhs)
2127 }
2128 }
2129
2130 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
2131 ///
2132 /// If `rhs` is larger or equal to the number of bits in `self`,
2133 /// the entire value is shifted out, and `0` is returned.
2134 ///
2135 /// # Examples
2136 ///
2137 /// ```
2138 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
2139 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
2140 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
2141 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
2142 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
2143 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
2144 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2145 ///
2146 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
2147 /// let mut running = start;
2148 /// for i in 0..160 {
2149 /// // The unbounded shift left by i is the same as `<< 1` i times
2150 /// assert_eq!(running, start.unbounded_shl(i));
2151 /// // Which is not always the case for a wrapping shift
2152 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
2153 ///
2154 /// running <<= 1;
2155 /// }
2156 /// ```
2157 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2158 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2159 #[must_use = "this returns the result of the operation, \
2160 without modifying the original"]
2161 #[inline]
2162 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2163 if rhs < Self::BITS {
2164 // SAFETY:
2165 // rhs is just checked to be in-range above
2166 unsafe { self.unchecked_shl(rhs) }
2167 } else {
2168 0
2169 }
2170 }
2171
2172 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2173 ///
2174 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2175 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2176 /// Otherwise, returns `Some(self << rhs)`.
2177 ///
2178 /// # Examples
2179 ///
2180 /// ```
2181 /// #![feature(exact_bitshifts)]
2182 ///
2183 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2184 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2185 /// ```
2186 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2187 #[must_use = "this returns the result of the operation, \
2188 without modifying the original"]
2189 #[inline]
2190 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2191 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2192 // SAFETY: rhs is checked above
2193 Some(unsafe { self.unchecked_shl(rhs) })
2194 } else {
2195 None
2196 }
2197 }
2198
2199 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2200 /// losslessly reversed `rhs` cannot be larger than
2201 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2202 ///
2203 /// # Safety
2204 ///
2205 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2206 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2207 /// i.e. when
2208 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2209 /// would return `None`.
2210 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2211 #[must_use = "this returns the result of the operation, \
2212 without modifying the original"]
2213 #[inline]
2214 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2215 assert_unsafe_precondition!(
2216 check_library_ub,
2217 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2218 (
2219 zeros: u32 = self.leading_zeros(),
2220 bits: u32 = <$SelfT>::BITS,
2221 rhs: u32 = rhs,
2222 ) => rhs <= zeros && rhs < bits,
2223 );
2224
2225 // SAFETY: this is guaranteed to be safe by the caller
2226 unsafe { self.unchecked_shl(rhs) }
2227 }
2228
2229 /// Checked shift right. Computes `self >> rhs`, returning `None`
2230 /// if `rhs` is larger than or equal to the number of bits in `self`.
2231 ///
2232 /// # Examples
2233 ///
2234 /// ```
2235 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2236 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2237 /// ```
2238 #[stable(feature = "wrapping", since = "1.7.0")]
2239 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2240 #[must_use = "this returns the result of the operation, \
2241 without modifying the original"]
2242 #[inline]
2243 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2244 // Not using overflowing_shr as that's a wrapping shift
2245 if rhs < Self::BITS {
2246 // SAFETY: just checked the RHS is in-range
2247 Some(unsafe { self.unchecked_shr(rhs) })
2248 } else {
2249 None
2250 }
2251 }
2252
2253 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2254 /// larger than or equal to the number of bits in `self`.
2255 ///
2256 /// # Panics
2257 ///
2258 /// ## Overflow behavior
2259 ///
2260 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2261 ///
2262 /// # Examples
2263 ///
2264 /// ```
2265 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2266 /// ```
2267 ///
2268 /// The following panics because of overflow:
2269 ///
2270 /// ```should_panic
2271 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2272 /// ```
2273 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2274 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2275 #[must_use = "this returns the result of the operation, \
2276 without modifying the original"]
2277 #[inline]
2278 #[track_caller]
2279 pub const fn strict_shr(self, rhs: u32) -> Self {
2280 let (a, b) = self.overflowing_shr(rhs);
2281 if b { imp::overflow_panic::shr() } else { a }
2282 }
2283
2284 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2285 /// `rhs` is less than the number of bits in `self`.
2286 ///
2287 /// # Safety
2288 ///
2289 /// This results in undefined behavior if `rhs` is larger than
2290 /// or equal to the number of bits in `self`,
2291 /// i.e. when [`checked_shr`] would return `None`.
2292 ///
2293 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2294 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2295 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2296 #[must_use = "this returns the result of the operation, \
2297 without modifying the original"]
2298 #[inline(always)]
2299 #[track_caller]
2300 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2301 assert_unsafe_precondition!(
2302 check_language_ub,
2303 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2304 (
2305 rhs: u32 = rhs,
2306 ) => rhs < <$ActualT>::BITS,
2307 );
2308
2309 // SAFETY: this is guaranteed to be safe by the caller.
2310 unsafe {
2311 intrinsics::unchecked_shr(self, rhs)
2312 }
2313 }
2314
2315 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2316 ///
2317 /// If `rhs` is larger or equal to the number of bits in `self`,
2318 /// the entire value is shifted out, and `0` is returned.
2319 ///
2320 /// # Examples
2321 ///
2322 /// ```
2323 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2324 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2325 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2326 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2327 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2328 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2329 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2330 ///
2331 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2332 /// let mut running = start;
2333 /// for i in 0..160 {
2334 /// // The unbounded shift right by i is the same as `>> 1` i times
2335 /// assert_eq!(running, start.unbounded_shr(i));
2336 /// // Which is not always the case for a wrapping shift
2337 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2338 ///
2339 /// running >>= 1;
2340 /// }
2341 /// ```
2342 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2343 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2344 #[must_use = "this returns the result of the operation, \
2345 without modifying the original"]
2346 #[inline]
2347 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2348 if rhs < Self::BITS {
2349 // SAFETY:
2350 // rhs is just checked to be in-range above
2351 unsafe { self.unchecked_shr(rhs) }
2352 } else {
2353 0
2354 }
2355 }
2356
2357 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2358 ///
2359 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2360 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2361 /// Otherwise, returns `Some(self >> rhs)`.
2362 ///
2363 /// # Examples
2364 ///
2365 /// ```
2366 /// #![feature(exact_bitshifts)]
2367 ///
2368 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2369 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2370 /// ```
2371 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2372 #[must_use = "this returns the result of the operation, \
2373 without modifying the original"]
2374 #[inline]
2375 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2376 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2377 // SAFETY: rhs is checked above
2378 Some(unsafe { self.unchecked_shr(rhs) })
2379 } else {
2380 None
2381 }
2382 }
2383
2384 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2385 /// losslessly reversed and `rhs` cannot be larger than
2386 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2387 ///
2388 /// # Safety
2389 ///
2390 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2391 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2392 /// i.e. when
2393 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2394 /// would return `None`.
2395 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2396 #[must_use = "this returns the result of the operation, \
2397 without modifying the original"]
2398 #[inline]
2399 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2400 assert_unsafe_precondition!(
2401 check_library_ub,
2402 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2403 (
2404 zeros: u32 = self.trailing_zeros(),
2405 bits: u32 = <$SelfT>::BITS,
2406 rhs: u32 = rhs,
2407 ) => rhs <= zeros && rhs < bits,
2408 );
2409
2410 // SAFETY: this is guaranteed to be safe by the caller
2411 unsafe { self.unchecked_shr(rhs) }
2412 }
2413
2414 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2415 /// overflow occurred.
2416 ///
2417 /// # Examples
2418 ///
2419 /// ```
2420 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2421 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2422 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2423 /// ```
2424 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2425 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2426 #[must_use = "this returns the result of the operation, \
2427 without modifying the original"]
2428 #[inline]
2429 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2430 let mut base = self;
2431 let mut acc: Self = 1;
2432
2433 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
2434 // change of base:
2435 // if base == 2 ** k, then
2436 // (2 ** k) ** n
2437 // == 2 ** (k * n)
2438 // == 1 << (k * n)
2439 let k = base.ilog2();
2440 let shift = try_opt!(k.checked_mul(exp));
2441 return (1 as Self).checked_shl(shift);
2442 }
2443
2444 if exp == 0 {
2445 return Some(1);
2446 }
2447
2448 if intrinsics::is_val_statically_known(exp) {
2449 while exp > 1 {
2450 if (exp & 1) == 1 {
2451 acc = try_opt!(acc.checked_mul(base));
2452 }
2453 exp /= 2;
2454 base = try_opt!(base.checked_mul(base));
2455 }
2456
2457 // since exp!=0, finally the exp must be 1.
2458 // Deal with the final bit of the exponent separately, since
2459 // squaring the base afterwards is not necessary and may cause a
2460 // needless overflow.
2461 return acc.checked_mul(base);
2462 }
2463
2464 loop {
2465 if (exp & 1) == 1 {
2466 acc = try_opt!(acc.checked_mul(base));
2467 // since exp!=0, finally the exp must be 1.
2468 if exp == 1 {
2469 return Some(acc);
2470 }
2471 }
2472 exp /= 2;
2473 base = try_opt!(base.checked_mul(base));
2474 }
2475 }
2476
2477 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2478 /// overflow occurred.
2479 ///
2480 /// # Panics
2481 ///
2482 /// ## Overflow behavior
2483 ///
2484 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2485 ///
2486 /// # Examples
2487 ///
2488 /// ```
2489 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2490 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2491 /// ```
2492 ///
2493 /// The following panics because of overflow:
2494 ///
2495 /// ```should_panic
2496 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2497 /// ```
2498 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2499 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2500 #[must_use = "this returns the result of the operation, \
2501 without modifying the original"]
2502 #[inline]
2503 #[track_caller]
2504 pub const fn strict_pow(self, exp: u32) -> Self {
2505 match self.checked_pow(exp) {
2506 None => imp::overflow_panic::pow(),
2507 Some(a) => a,
2508 }
2509 }
2510
2511 /// Saturating integer addition. Computes `self + rhs`, saturating at
2512 /// the numeric bounds instead of overflowing.
2513 ///
2514 /// # Examples
2515 ///
2516 /// ```
2517 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2518 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2519 /// ```
2520 #[stable(feature = "rust1", since = "1.0.0")]
2521 #[must_use = "this returns the result of the operation, \
2522 without modifying the original"]
2523 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2524 #[inline(always)]
2525 pub const fn saturating_add(self, rhs: Self) -> Self {
2526 intrinsics::saturating_add(self, rhs)
2527 }
2528
2529 /// Saturating addition with a signed integer. Computes `self + rhs`,
2530 /// saturating at the numeric bounds instead of overflowing.
2531 ///
2532 /// # Examples
2533 ///
2534 /// ```
2535 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2536 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2537 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2538 /// ```
2539 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2540 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2541 #[must_use = "this returns the result of the operation, \
2542 without modifying the original"]
2543 #[inline]
2544 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2545 let (res, overflow) = self.overflowing_add(rhs as Self);
2546 if overflow == (rhs < 0) {
2547 res
2548 } else if overflow {
2549 Self::MAX
2550 } else {
2551 0
2552 }
2553 }
2554
2555 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2556 /// at the numeric bounds instead of overflowing.
2557 ///
2558 /// # Examples
2559 ///
2560 /// ```
2561 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2562 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2563 /// ```
2564 #[stable(feature = "rust1", since = "1.0.0")]
2565 #[must_use = "this returns the result of the operation, \
2566 without modifying the original"]
2567 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2568 #[inline(always)]
2569 pub const fn saturating_sub(self, rhs: Self) -> Self {
2570 intrinsics::saturating_sub(self, rhs)
2571 }
2572
2573 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2574 /// the numeric bounds instead of overflowing.
2575 ///
2576 /// # Examples
2577 ///
2578 /// ```
2579 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2580 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2581 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2582 /// ```
2583 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2584 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2585 #[must_use = "this returns the result of the operation, \
2586 without modifying the original"]
2587 #[inline]
2588 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2589 let (res, overflow) = self.overflowing_sub_signed(rhs);
2590
2591 if !overflow {
2592 res
2593 } else if rhs < 0 {
2594 Self::MAX
2595 } else {
2596 0
2597 }
2598 }
2599
2600 /// Saturating integer multiplication. Computes `self * rhs`,
2601 /// saturating at the numeric bounds instead of overflowing.
2602 ///
2603 /// # Examples
2604 ///
2605 /// ```
2606 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2607 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2608 /// ```
2609 #[stable(feature = "wrapping", since = "1.7.0")]
2610 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2611 #[must_use = "this returns the result of the operation, \
2612 without modifying the original"]
2613 #[inline]
2614 pub const fn saturating_mul(self, rhs: Self) -> Self {
2615 match self.checked_mul(rhs) {
2616 Some(x) => x,
2617 None => Self::MAX,
2618 }
2619 }
2620
2621 /// Saturating integer division. Computes `self / rhs`, saturating at the
2622 /// numeric bounds instead of overflowing.
2623 ///
2624 /// # Panics
2625 ///
2626 /// This function will panic if `rhs` is zero.
2627 ///
2628 /// # Examples
2629 ///
2630 /// ```
2631 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2632 ///
2633 /// ```
2634 #[stable(feature = "saturating_div", since = "1.58.0")]
2635 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2636 #[must_use = "this returns the result of the operation, \
2637 without modifying the original"]
2638 #[inline]
2639 #[track_caller]
2640 pub const fn saturating_div(self, rhs: Self) -> Self {
2641 // on unsigned types, there is no overflow in integer division
2642 self.wrapping_div(rhs)
2643 }
2644
2645 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2646 /// saturating at the numeric bounds instead of overflowing.
2647 ///
2648 /// # Examples
2649 ///
2650 /// ```
2651 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2652 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2653 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2654 /// ```
2655 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2656 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2657 #[must_use = "this returns the result of the operation, \
2658 without modifying the original"]
2659 #[inline]
2660 pub const fn saturating_pow(self, exp: u32) -> Self {
2661 match self.checked_pow(exp) {
2662 Some(x) => x,
2663 None => Self::MAX,
2664 }
2665 }
2666
2667 /// Wrapping (modular) addition. Computes `self + rhs`,
2668 /// wrapping around at the boundary of the type.
2669 ///
2670 /// # Examples
2671 ///
2672 /// ```
2673 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2674 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2675 /// ```
2676 #[stable(feature = "rust1", since = "1.0.0")]
2677 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2678 #[must_use = "this returns the result of the operation, \
2679 without modifying the original"]
2680 #[inline(always)]
2681 pub const fn wrapping_add(self, rhs: Self) -> Self {
2682 intrinsics::wrapping_add(self, rhs)
2683 }
2684
2685 /// Wrapping (modular) addition with a signed integer. Computes
2686 /// `self + rhs`, wrapping around at the boundary of the type.
2687 ///
2688 /// # Examples
2689 ///
2690 /// ```
2691 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2692 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2693 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2694 /// ```
2695 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2696 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2697 #[must_use = "this returns the result of the operation, \
2698 without modifying the original"]
2699 #[inline]
2700 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2701 self.wrapping_add(rhs as Self)
2702 }
2703
2704 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2705 /// wrapping around at the boundary of the type.
2706 ///
2707 /// # Examples
2708 ///
2709 /// ```
2710 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2711 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2712 /// ```
2713 #[stable(feature = "rust1", since = "1.0.0")]
2714 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2715 #[must_use = "this returns the result of the operation, \
2716 without modifying the original"]
2717 #[inline(always)]
2718 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2719 intrinsics::wrapping_sub(self, rhs)
2720 }
2721
2722 /// Wrapping (modular) subtraction with a signed integer. Computes
2723 /// `self - rhs`, wrapping around at the boundary of the type.
2724 ///
2725 /// # Examples
2726 ///
2727 /// ```
2728 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2729 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2730 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2731 /// ```
2732 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2733 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2734 #[must_use = "this returns the result of the operation, \
2735 without modifying the original"]
2736 #[inline]
2737 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2738 self.wrapping_sub(rhs as Self)
2739 }
2740
2741 /// Wrapping (modular) multiplication. Computes `self *
2742 /// rhs`, wrapping around at the boundary of the type.
2743 ///
2744 /// # Examples
2745 ///
2746 /// Please note that this example is shared among integer types, which is why `u8` is used.
2747 ///
2748 /// ```
2749 /// assert_eq!(10u8.wrapping_mul(12), 120);
2750 /// assert_eq!(25u8.wrapping_mul(12), 44);
2751 /// ```
2752 #[stable(feature = "rust1", since = "1.0.0")]
2753 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2754 #[must_use = "this returns the result of the operation, \
2755 without modifying the original"]
2756 #[inline(always)]
2757 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2758 intrinsics::wrapping_mul(self, rhs)
2759 }
2760
2761 /// Wrapping (modular) division. Computes `self / rhs`.
2762 ///
2763 /// Wrapped division on unsigned types is just normal division. There's
2764 /// no way wrapping could ever happen. This function exists so that all
2765 /// operations are accounted for in the wrapping operations.
2766 ///
2767 /// # Panics
2768 ///
2769 /// This function will panic if `rhs` is zero.
2770 ///
2771 /// # Examples
2772 ///
2773 /// ```
2774 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2775 /// ```
2776 #[stable(feature = "num_wrapping", since = "1.2.0")]
2777 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2778 #[must_use = "this returns the result of the operation, \
2779 without modifying the original"]
2780 #[inline(always)]
2781 #[track_caller]
2782 pub const fn wrapping_div(self, rhs: Self) -> Self {
2783 self / rhs
2784 }
2785
2786 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2787 ///
2788 /// Wrapped division on unsigned types is just normal division. There's
2789 /// no way wrapping could ever happen. This function exists so that all
2790 /// operations are accounted for in the wrapping operations. Since, for
2791 /// the positive integers, all common definitions of division are equal,
2792 /// this is exactly equal to `self.wrapping_div(rhs)`.
2793 ///
2794 /// # Panics
2795 ///
2796 /// This function will panic if `rhs` is zero.
2797 ///
2798 /// # Examples
2799 ///
2800 /// ```
2801 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2802 /// ```
2803 #[stable(feature = "euclidean_division", since = "1.38.0")]
2804 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2805 #[must_use = "this returns the result of the operation, \
2806 without modifying the original"]
2807 #[inline(always)]
2808 #[track_caller]
2809 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2810 self / rhs
2811 }
2812
2813 /// Wrapping (modular) remainder. Computes `self % rhs`.
2814 ///
2815 /// Wrapped remainder calculation on unsigned types is just the regular
2816 /// remainder calculation. There's no way wrapping could ever happen.
2817 /// This function exists so that all operations are accounted for in the
2818 /// wrapping operations.
2819 ///
2820 /// # Panics
2821 ///
2822 /// This function will panic if `rhs` is zero.
2823 ///
2824 /// # Examples
2825 ///
2826 /// ```
2827 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2828 /// ```
2829 #[stable(feature = "num_wrapping", since = "1.2.0")]
2830 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2831 #[must_use = "this returns the result of the operation, \
2832 without modifying the original"]
2833 #[inline(always)]
2834 #[track_caller]
2835 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2836 self % rhs
2837 }
2838
2839 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2840 ///
2841 /// Wrapped modulo calculation on unsigned types is just the regular
2842 /// remainder calculation. There's no way wrapping could ever happen.
2843 /// This function exists so that all operations are accounted for in the
2844 /// wrapping operations. Since, for the positive integers, all common
2845 /// definitions of division are equal, this is exactly equal to
2846 /// `self.wrapping_rem(rhs)`.
2847 ///
2848 /// # Panics
2849 ///
2850 /// This function will panic if `rhs` is zero.
2851 ///
2852 /// # Examples
2853 ///
2854 /// ```
2855 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2856 /// ```
2857 #[stable(feature = "euclidean_division", since = "1.38.0")]
2858 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2859 #[must_use = "this returns the result of the operation, \
2860 without modifying the original"]
2861 #[inline(always)]
2862 #[track_caller]
2863 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2864 self % rhs
2865 }
2866
2867 /// Wrapping (modular) negation. Computes `-self`,
2868 /// wrapping around at the boundary of the type.
2869 ///
2870 /// Since unsigned types do not have negative equivalents
2871 /// all applications of this function will wrap (except for `-0`).
2872 /// For values smaller than the corresponding signed type's maximum
2873 /// the result is the same as casting the corresponding signed value.
2874 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2875 /// `MAX` is the corresponding signed type's maximum.
2876 ///
2877 /// # Examples
2878 ///
2879 /// ```
2880 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2881 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2882 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2883 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2884 /// ```
2885 #[stable(feature = "num_wrapping", since = "1.2.0")]
2886 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2887 #[must_use = "this returns the result of the operation, \
2888 without modifying the original"]
2889 #[inline(always)]
2890 pub const fn wrapping_neg(self) -> Self {
2891 (0 as $SelfT).wrapping_sub(self)
2892 }
2893
2894 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2895 /// where `mask` removes any high-order bits of `rhs` that
2896 /// would cause the shift to exceed the bitwidth of the type.
2897 ///
2898 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2899 /// does *not* give the same result as doing the shift in infinite precision
2900 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2901 /// do on many processors, and is what the `<<` operator does when overflow
2902 /// checks are disabled, but numerically it's weird. Consider, instead,
2903 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2904 ///
2905 /// Note that this is *not* the same as a rotate-left; the
2906 /// RHS of a wrapping shift-left is restricted to the range
2907 /// of the type, rather than the bits shifted out of the LHS
2908 /// being returned to the other end. The primitive integer
2909 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2910 /// which may be what you want instead.
2911 ///
2912 /// # Examples
2913 ///
2914 /// ```
2915 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2916 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2917 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2918 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2919 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2920 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2921 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2922 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2923 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2924 /// ```
2925 #[stable(feature = "num_wrapping", since = "1.2.0")]
2926 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2927 #[must_use = "this returns the result of the operation, \
2928 without modifying the original"]
2929 #[inline(always)]
2930 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2931 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2932 // out of bounds
2933 unsafe {
2934 self.unchecked_shl(rhs & (Self::BITS - 1))
2935 }
2936 }
2937
2938 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2939 /// where `mask` removes any high-order bits of `rhs` that
2940 /// would cause the shift to exceed the bitwidth of the type.
2941 ///
2942 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2943 /// does *not* give the same result as doing the shift in infinite precision
2944 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2945 /// do on many processors, and is what the `>>` operator does when overflow
2946 /// checks are disabled, but numerically it's weird. Consider, instead,
2947 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2948 ///
2949 /// Note that this is *not* the same as a rotate-right; the
2950 /// RHS of a wrapping shift-right is restricted to the range
2951 /// of the type, rather than the bits shifted out of the LHS
2952 /// being returned to the other end. The primitive integer
2953 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2954 /// which may be what you want instead.
2955 ///
2956 /// # Examples
2957 ///
2958 /// ```
2959 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2960 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2961 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2962 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2963 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2964 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2965 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2966 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2967 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2968 /// ```
2969 #[stable(feature = "num_wrapping", since = "1.2.0")]
2970 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2971 #[must_use = "this returns the result of the operation, \
2972 without modifying the original"]
2973 #[inline(always)]
2974 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2975 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2976 // out of bounds
2977 unsafe {
2978 self.unchecked_shr(rhs & (Self::BITS - 1))
2979 }
2980 }
2981
2982 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2983 /// wrapping around at the boundary of the type.
2984 ///
2985 /// # Examples
2986 ///
2987 /// ```
2988 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2989 /// assert_eq!(3u8.wrapping_pow(6), 217);
2990 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2991 /// ```
2992 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2993 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2994 #[must_use = "this returns the result of the operation, \
2995 without modifying the original"]
2996 #[inline]
2997 pub const fn wrapping_pow(self, exp: u32) -> Self {
2998 let (a, _) = self.overflowing_pow(exp);
2999 a
3000 }
3001
3002 /// Calculates `self` + `rhs`.
3003 ///
3004 /// Returns a tuple of the addition along with a boolean indicating
3005 /// whether an arithmetic overflow would occur. If an overflow would
3006 /// have occurred then the wrapped value is returned.
3007 ///
3008 /// # Examples
3009 ///
3010 /// ```
3011 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
3012 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
3013 /// ```
3014 #[stable(feature = "wrapping", since = "1.7.0")]
3015 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3016 #[must_use = "this returns the result of the operation, \
3017 without modifying the original"]
3018 #[inline(always)]
3019 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
3020 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
3021 (a as Self, b)
3022 }
3023
3024 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
3025 /// the sum and the output carry (in that order).
3026 ///
3027 /// Performs "ternary addition" of two integer operands and a carry-in
3028 /// bit, and returns an output integer and a carry-out bit. This allows
3029 /// chaining together multiple additions to create a wider addition, and
3030 /// can be useful for bignum addition.
3031 ///
3032 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
3033 ///
3034 /// If the input carry is false, this method is equivalent to
3035 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
3036 /// equal to the overflow flag. Note that although carry and overflow
3037 /// flags are similar for unsigned integers, they are different for
3038 /// signed integers.
3039 ///
3040 /// # Examples
3041 ///
3042 /// ```
3043 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3044 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3045 /// // ---------
3046 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
3047 ///
3048 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
3049 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3050 /// let carry0 = false;
3051 ///
3052 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
3053 /// assert_eq!(carry1, true);
3054 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
3055 /// assert_eq!(carry2, false);
3056 ///
3057 /// assert_eq!((sum1, sum0), (9, 6));
3058 /// ```
3059 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3060 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3061 #[must_use = "this returns the result of the operation, \
3062 without modifying the original"]
3063 #[inline]
3064 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
3065 // note: longer-term this should be done via an intrinsic, but this has been shown
3066 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3067 let (a, c1) = self.overflowing_add(rhs);
3068 let (b, c2) = a.overflowing_add(carry as $SelfT);
3069 // Ideally LLVM would know this is disjoint without us telling them,
3070 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
3071 // SAFETY: Only one of `c1` and `c2` can be set.
3072 // For c1 to be set we need to have overflowed, but if we did then
3073 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
3074 // overflow because it's adding at most `1` (since it came from `bool`)
3075 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3076 }
3077
3078 /// Calculates `self` + `rhs` with a signed `rhs`.
3079 ///
3080 /// Returns a tuple of the addition along with a boolean indicating
3081 /// whether an arithmetic overflow would occur. If an overflow would
3082 /// have occurred then the wrapped value is returned.
3083 ///
3084 /// # Examples
3085 ///
3086 /// ```
3087 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
3088 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
3089 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
3090 /// ```
3091 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
3092 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
3093 #[must_use = "this returns the result of the operation, \
3094 without modifying the original"]
3095 #[inline]
3096 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
3097 let (res, overflowed) = self.overflowing_add(rhs as Self);
3098 (res, overflowed ^ (rhs < 0))
3099 }
3100
3101 /// Calculates `self` - `rhs`.
3102 ///
3103 /// Returns a tuple of the subtraction along with a boolean indicating
3104 /// whether an arithmetic overflow would occur. If an overflow would
3105 /// have occurred then the wrapped value is returned.
3106 ///
3107 /// # Examples
3108 ///
3109 /// ```
3110 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
3111 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
3112 /// ```
3113 #[stable(feature = "wrapping", since = "1.7.0")]
3114 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3115 #[must_use = "this returns the result of the operation, \
3116 without modifying the original"]
3117 #[inline(always)]
3118 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
3119 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
3120 (a as Self, b)
3121 }
3122
3123 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
3124 /// containing the difference and the output borrow.
3125 ///
3126 /// Performs "ternary subtraction" by subtracting both an integer
3127 /// operand and a borrow-in bit from `self`, and returns an output
3128 /// integer and a borrow-out bit. This allows chaining together multiple
3129 /// subtractions to create a wider subtraction, and can be useful for
3130 /// bignum subtraction.
3131 ///
3132 /// # Examples
3133 ///
3134 /// ```
3135 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
3136 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3137 /// // ---------
3138 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3139 ///
3140 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3141 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3142 /// let borrow0 = false;
3143 ///
3144 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3145 /// assert_eq!(borrow1, true);
3146 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3147 /// assert_eq!(borrow2, false);
3148 ///
3149 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3150 /// ```
3151 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3152 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3153 #[must_use = "this returns the result of the operation, \
3154 without modifying the original"]
3155 #[inline]
3156 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3157 // note: longer-term this should be done via an intrinsic, but this has been shown
3158 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3159 let (a, c1) = self.overflowing_sub(rhs);
3160 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3161 // SAFETY: Only one of `c1` and `c2` can be set.
3162 // For c1 to be set we need to have underflowed, but if we did then
3163 // `a` is nonzero, which means that `c2` cannot possibly
3164 // underflow because it's subtracting at most `1` (since it came from `bool`)
3165 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3166 }
3167
3168 /// Calculates `self` - `rhs` with a signed `rhs`
3169 ///
3170 /// Returns a tuple of the subtraction along with a boolean indicating
3171 /// whether an arithmetic overflow would occur. If an overflow would
3172 /// have occurred then the wrapped value is returned.
3173 ///
3174 /// # Examples
3175 ///
3176 /// ```
3177 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3178 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3179 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3180 /// ```
3181 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3182 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3183 #[must_use = "this returns the result of the operation, \
3184 without modifying the original"]
3185 #[inline]
3186 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3187 let (res, overflow) = self.overflowing_sub(rhs as Self);
3188
3189 (res, overflow ^ (rhs < 0))
3190 }
3191
3192 /// Computes the absolute difference between `self` and `other`.
3193 ///
3194 /// # Examples
3195 ///
3196 /// ```
3197 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3198 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3199 /// ```
3200 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3201 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3202 #[must_use = "this returns the result of the operation, \
3203 without modifying the original"]
3204 #[inline]
3205 pub const fn abs_diff(self, other: Self) -> Self {
3206 if size_of::<Self>() == 1 {
3207 // Trick LLVM into generating the psadbw instruction when SSE2
3208 // is available and this function is autovectorized for u8's.
3209 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3210 } else {
3211 if self < other {
3212 other - self
3213 } else {
3214 self - other
3215 }
3216 }
3217 }
3218
3219 /// Calculates the multiplication of `self` and `rhs`.
3220 ///
3221 /// Returns a tuple of the multiplication along with a boolean
3222 /// indicating whether an arithmetic overflow would occur. If an
3223 /// overflow would have occurred then the wrapped value is returned.
3224 ///
3225 /// If you want the *value* of the overflow, rather than just *whether*
3226 /// an overflow occurred, see [`Self::carrying_mul`].
3227 ///
3228 /// # Examples
3229 ///
3230 /// Please note that this example is shared among integer types, which is why `u32` is used.
3231 ///
3232 /// ```
3233 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3234 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3235 /// ```
3236 #[stable(feature = "wrapping", since = "1.7.0")]
3237 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3238 #[must_use = "this returns the result of the operation, \
3239 without modifying the original"]
3240 #[inline(always)]
3241 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3242 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3243 (a as Self, b)
3244 }
3245
3246 /// Calculates the "full multiplication" `self * rhs + carry`
3247 /// without the possibility to overflow.
3248 ///
3249 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3250 /// of the result as two separate values, in that order.
3251 ///
3252 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3253 /// additional amount of overflow. This allows for chaining together multiple
3254 /// multiplications to create "big integers" which represent larger values.
3255 ///
3256 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3257 ///
3258 /// # Examples
3259 ///
3260 /// Please note that this example is shared among integer types, which is why `u32` is used.
3261 ///
3262 /// ```
3263 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3264 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3265 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3266 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3267 #[doc = concat!("assert_eq!(",
3268 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3269 "(0, ", stringify!($SelfT), "::MAX));"
3270 )]
3271 /// ```
3272 ///
3273 /// This is the core operation needed for scalar multiplication when
3274 /// implementing it for wider-than-native types.
3275 ///
3276 /// ```
3277 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3278 /// let mut carry = 0;
3279 /// for d in little_endian_digits.iter_mut() {
3280 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3281 /// }
3282 /// if carry != 0 {
3283 /// little_endian_digits.push(carry);
3284 /// }
3285 /// }
3286 ///
3287 /// let mut v = vec![10, 20];
3288 /// scalar_mul_eq(&mut v, 3);
3289 /// assert_eq!(v, [30, 60]);
3290 ///
3291 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3292 /// let mut v = vec![0x4321, 0x8765];
3293 /// scalar_mul_eq(&mut v, 0xFEED);
3294 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3295 /// ```
3296 ///
3297 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3298 /// except that it gives the value of the overflow instead of just whether one happened:
3299 ///
3300 /// ```
3301 /// # #![allow(unused_features)]
3302 /// #![feature(const_unsigned_bigint_helpers)]
3303 /// let r = u8::carrying_mul(7, 13, 0);
3304 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3305 /// let r = u8::carrying_mul(13, 42, 0);
3306 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3307 /// ```
3308 ///
3309 /// The value of the first field in the returned tuple matches what you'd get
3310 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3311 /// [`wrapping_add`](Self::wrapping_add) methods:
3312 ///
3313 /// ```
3314 /// # #![allow(unused_features)]
3315 /// #![feature(const_unsigned_bigint_helpers)]
3316 /// assert_eq!(
3317 /// 789_u16.carrying_mul(456, 123).0,
3318 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3319 /// );
3320 /// ```
3321 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3322 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3323 #[must_use = "this returns the result of the operation, \
3324 without modifying the original"]
3325 #[inline]
3326 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3327 Self::carrying_mul_add(self, rhs, carry, 0)
3328 }
3329
3330 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3331 ///
3332 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3333 /// of the result as two separate values, in that order.
3334 ///
3335 /// This cannot overflow, as the double-width result has exactly enough
3336 /// space for the largest possible result. This is equivalent to how, in
3337 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3338 ///
3339 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3340 /// additional amount of overflow. This allows for chaining together multiple
3341 /// multiplications to create "big integers" which represent larger values.
3342 ///
3343 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3344 ///
3345 /// # Examples
3346 ///
3347 /// Please note that this example is shared between integer types,
3348 /// which explains why `u32` is used here.
3349 ///
3350 /// ```
3351 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3352 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3353 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3354 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3355 #[doc = concat!("assert_eq!(",
3356 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3357 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3358 )]
3359 /// ```
3360 ///
3361 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3362 ///
3363 /// Please note that this example is shared between integer types,
3364 /// using `u8` for simplicity of the demonstration.
3365 ///
3366 /// ```
3367 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3368 /// let mut out = [0; N];
3369 /// for j in 0..N {
3370 /// let mut carry = 0;
3371 /// for i in 0..(N - j) {
3372 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3373 /// }
3374 /// }
3375 /// out
3376 /// }
3377 ///
3378 /// // -1 * -1 == 1
3379 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3380 ///
3381 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3382 /// assert_eq!(
3383 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3384 /// u32::to_le_bytes(0xcffc982d)
3385 /// );
3386 /// ```
3387 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3388 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3389 #[must_use = "this returns the result of the operation, \
3390 without modifying the original"]
3391 #[inline]
3392 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3393 intrinsics::carrying_mul_add(self, rhs, carry, add)
3394 }
3395
3396 /// Calculates the divisor when `self` is divided by `rhs`.
3397 ///
3398 /// Returns a tuple of the divisor along with a boolean indicating
3399 /// whether an arithmetic overflow would occur. Note that for unsigned
3400 /// integers overflow never occurs, so the second value is always
3401 /// `false`.
3402 ///
3403 /// # Panics
3404 ///
3405 /// This function will panic if `rhs` is zero.
3406 ///
3407 /// # Examples
3408 ///
3409 /// ```
3410 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3411 /// ```
3412 #[inline(always)]
3413 #[stable(feature = "wrapping", since = "1.7.0")]
3414 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3415 #[must_use = "this returns the result of the operation, \
3416 without modifying the original"]
3417 #[track_caller]
3418 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3419 (self / rhs, false)
3420 }
3421
3422 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3423 ///
3424 /// Returns a tuple of the divisor along with a boolean indicating
3425 /// whether an arithmetic overflow would occur. Note that for unsigned
3426 /// integers overflow never occurs, so the second value is always
3427 /// `false`.
3428 /// Since, for the positive integers, all common
3429 /// definitions of division are equal, this
3430 /// is exactly equal to `self.overflowing_div(rhs)`.
3431 ///
3432 /// # Panics
3433 ///
3434 /// This function will panic if `rhs` is zero.
3435 ///
3436 /// # Examples
3437 ///
3438 /// ```
3439 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3440 /// ```
3441 #[inline(always)]
3442 #[stable(feature = "euclidean_division", since = "1.38.0")]
3443 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3444 #[must_use = "this returns the result of the operation, \
3445 without modifying the original"]
3446 #[track_caller]
3447 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3448 (self / rhs, false)
3449 }
3450
3451 /// Calculates the remainder when `self` is divided by `rhs`.
3452 ///
3453 /// Returns a tuple of the remainder after dividing along with a boolean
3454 /// indicating whether an arithmetic overflow would occur. Note that for
3455 /// unsigned integers overflow never occurs, so the second value is
3456 /// always `false`.
3457 ///
3458 /// # Panics
3459 ///
3460 /// This function will panic if `rhs` is zero.
3461 ///
3462 /// # Examples
3463 ///
3464 /// ```
3465 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3466 /// ```
3467 #[inline(always)]
3468 #[stable(feature = "wrapping", since = "1.7.0")]
3469 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3470 #[must_use = "this returns the result of the operation, \
3471 without modifying the original"]
3472 #[track_caller]
3473 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3474 (self % rhs, false)
3475 }
3476
3477 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3478 ///
3479 /// Returns a tuple of the modulo after dividing along with a boolean
3480 /// indicating whether an arithmetic overflow would occur. Note that for
3481 /// unsigned integers overflow never occurs, so the second value is
3482 /// always `false`.
3483 /// Since, for the positive integers, all common
3484 /// definitions of division are equal, this operation
3485 /// is exactly equal to `self.overflowing_rem(rhs)`.
3486 ///
3487 /// # Panics
3488 ///
3489 /// This function will panic if `rhs` is zero.
3490 ///
3491 /// # Examples
3492 ///
3493 /// ```
3494 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3495 /// ```
3496 #[inline(always)]
3497 #[stable(feature = "euclidean_division", since = "1.38.0")]
3498 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3499 #[must_use = "this returns the result of the operation, \
3500 without modifying the original"]
3501 #[track_caller]
3502 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3503 (self % rhs, false)
3504 }
3505
3506 /// Negates self in an overflowing fashion.
3507 ///
3508 /// Returns `!self + 1` using wrapping operations to return the value
3509 /// that represents the negation of this unsigned value. Note that for
3510 /// positive unsigned values overflow always occurs, but negating 0 does
3511 /// not overflow.
3512 ///
3513 /// # Examples
3514 ///
3515 /// ```
3516 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3517 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3518 /// ```
3519 #[inline(always)]
3520 #[stable(feature = "wrapping", since = "1.7.0")]
3521 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3522 #[must_use = "this returns the result of the operation, \
3523 without modifying the original"]
3524 pub const fn overflowing_neg(self) -> (Self, bool) {
3525 ((!self).wrapping_add(1), self != 0)
3526 }
3527
3528 /// Shifts self left by `rhs` bits.
3529 ///
3530 /// Returns a tuple of the shifted version of self along with a boolean
3531 /// indicating whether the shift value was larger than or equal to the
3532 /// number of bits. If the shift value is too large, then value is
3533 /// masked (N-1) where N is the number of bits, and this value is then
3534 /// used to perform the shift.
3535 ///
3536 /// # Examples
3537 ///
3538 /// ```
3539 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3540 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3541 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3542 /// ```
3543 #[stable(feature = "wrapping", since = "1.7.0")]
3544 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3545 #[must_use = "this returns the result of the operation, \
3546 without modifying the original"]
3547 #[inline(always)]
3548 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3549 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3550 }
3551
3552 /// Shifts self right by `rhs` bits.
3553 ///
3554 /// Returns a tuple of the shifted version of self along with a boolean
3555 /// indicating whether the shift value was larger than or equal to the
3556 /// number of bits. If the shift value is too large, then value is
3557 /// masked (N-1) where N is the number of bits, and this value is then
3558 /// used to perform the shift.
3559 ///
3560 /// # Examples
3561 ///
3562 /// ```
3563 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3564 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3565 /// ```
3566 #[stable(feature = "wrapping", since = "1.7.0")]
3567 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3568 #[must_use = "this returns the result of the operation, \
3569 without modifying the original"]
3570 #[inline(always)]
3571 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3572 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3573 }
3574
3575 /// Raises self to the power of `exp`, using exponentiation by squaring.
3576 ///
3577 /// Returns a tuple of the exponentiation along with a bool indicating
3578 /// whether an overflow happened.
3579 ///
3580 /// # Examples
3581 ///
3582 /// ```
3583 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3584 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3585 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3586 /// ```
3587 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3588 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3589 #[must_use = "this returns the result of the operation, \
3590 without modifying the original"]
3591 #[inline]
3592 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3593 let mut base = self;
3594 let mut acc: Self = 1;
3595 let mut overflow = false;
3596 let mut tmp_overflow;
3597
3598 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
3599 // change of base:
3600 // if base == 2 ** k, then
3601 // (2 ** k) ** n
3602 // == 2 ** (k * n)
3603 // == 1 << (k * n)
3604 let k = base.ilog2();
3605 let Some(shift) = k.checked_mul(exp) else {
3606 return (0, true)
3607 };
3608 return ((1 as Self).unbounded_shl(shift), shift >= Self::BITS)
3609 }
3610
3611 if exp == 0 {
3612 return (1, false);
3613 }
3614
3615 if intrinsics::is_val_statically_known(exp) {
3616 while exp > 1 {
3617 if (exp & 1) == 1 {
3618 (acc, tmp_overflow) = acc.overflowing_mul(base);
3619 overflow |= tmp_overflow;
3620 }
3621 exp /= 2;
3622 (base, tmp_overflow) = base.overflowing_mul(base);
3623 overflow |= tmp_overflow;
3624 }
3625
3626 // since exp!=0, finally the exp must be 1.
3627 // Deal with the final bit of the exponent separately, since
3628 // squaring the base afterwards is not necessary and may cause a
3629 // needless overflow.
3630 (acc, tmp_overflow) = acc.overflowing_mul(base);
3631 overflow |= tmp_overflow;
3632 return (acc, overflow);
3633 }
3634
3635 loop {
3636 if (exp & 1) == 1 {
3637 (acc, tmp_overflow) = acc.overflowing_mul(base);
3638 overflow |= tmp_overflow;
3639 // since exp!=0, finally the exp must be 1.
3640 if exp == 1 {
3641 return (acc, overflow);
3642 }
3643 }
3644 exp /= 2;
3645 (base, tmp_overflow) = base.overflowing_mul(base);
3646 overflow |= tmp_overflow;
3647 }
3648 }
3649
3650 /// Raises self to the power of `exp`, using exponentiation by squaring.
3651 ///
3652 /// # Examples
3653 ///
3654 /// ```
3655 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3656 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3657 /// ```
3658 #[stable(feature = "rust1", since = "1.0.0")]
3659 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3660 #[must_use = "this returns the result of the operation, \
3661 without modifying the original"]
3662 #[inline]
3663 #[rustc_inherit_overflow_checks]
3664 pub const fn pow(self, exp: u32) -> Self {
3665 if intrinsics::overflow_checks() {
3666 self.strict_pow(exp)
3667 } else {
3668 self.wrapping_pow(exp)
3669 }
3670 }
3671
3672 /// Returns the square root of the number, rounded down.
3673 ///
3674 /// # Examples
3675 ///
3676 /// ```
3677 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3678 /// ```
3679 #[stable(feature = "isqrt", since = "1.84.0")]
3680 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3681 #[must_use = "this returns the result of the operation, \
3682 without modifying the original"]
3683 #[inline]
3684 pub const fn isqrt(self) -> Self {
3685 let result = imp::int_sqrt::$ActualT(self as $ActualT) as Self;
3686
3687 // Inform the optimizer what the range of outputs is. If testing
3688 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3689 // test failed, it's because your edits caused these assertions or
3690 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3691 //
3692 // SAFETY: Integer square root is a monotonically nondecreasing
3693 // function, which means that increasing the input will never
3694 // cause the output to decrease. Thus, since the input for unsigned
3695 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3696 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]` and bounding the
3697 // input by `[1, <$ActualT>::MAX]` bounds sqrt(n) by
3698 // `[sqrt(1), sqrt(<$ActualT>::MAX)]`.
3699 unsafe {
3700 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3701 crate::hint::assert_unchecked(result <= MAX_RESULT)
3702 }
3703
3704 if self >= 1 {
3705 // SAFETY: The above statements about monotonicity also apply here.
3706 // Since the input in this branch is bounded by `[1, <$ActualT>::MAX]`,
3707 // sqrt(n) is bounded by `[sqrt(1), sqrt(<$ActualT>::MAX)]`, and
3708 // `sqrt(1) == 1`.
3709 unsafe { crate::hint::assert_unchecked(result >= 1) }
3710 }
3711
3712 // SAFETY: the isqrt implementation returns the square root and rounds down,
3713 // meaning `result * result <= self`. This implies `result <= self`.
3714 // The compiler needs both to optimize for both.
3715 // `result * result <= self` implies the multiplication will not overflow.
3716 unsafe {
3717 crate::hint::assert_unchecked(result.unchecked_mul(result) <= self);
3718 crate::hint::assert_unchecked(result <= self);
3719 }
3720
3721 result
3722 }
3723
3724 /// Performs Euclidean division.
3725 ///
3726 /// Since, for the positive integers, all common
3727 /// definitions of division are equal, this
3728 /// is exactly equal to `self / rhs`.
3729 ///
3730 /// # Panics
3731 ///
3732 /// This function will panic if `rhs` is zero.
3733 ///
3734 /// # Examples
3735 ///
3736 /// ```
3737 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3738 /// ```
3739 #[stable(feature = "euclidean_division", since = "1.38.0")]
3740 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3741 #[must_use = "this returns the result of the operation, \
3742 without modifying the original"]
3743 #[inline(always)]
3744 #[track_caller]
3745 pub const fn div_euclid(self, rhs: Self) -> Self {
3746 self / rhs
3747 }
3748
3749
3750 /// Calculates the least remainder of `self` when divided by
3751 /// `rhs`.
3752 ///
3753 /// Since, for the positive integers, all common
3754 /// definitions of division are equal, this
3755 /// is exactly equal to `self % rhs`.
3756 ///
3757 /// # Panics
3758 ///
3759 /// This function will panic if `rhs` is zero.
3760 ///
3761 /// # Examples
3762 ///
3763 /// ```
3764 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3765 /// ```
3766 #[doc(alias = "modulo", alias = "mod")]
3767 #[stable(feature = "euclidean_division", since = "1.38.0")]
3768 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3769 #[must_use = "this returns the result of the operation, \
3770 without modifying the original"]
3771 #[inline(always)]
3772 #[track_caller]
3773 pub const fn rem_euclid(self, rhs: Self) -> Self {
3774 self % rhs
3775 }
3776
3777 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3778 ///
3779 /// This is the same as performing `self / rhs` for all unsigned integers.
3780 ///
3781 /// # Panics
3782 ///
3783 /// This function will panic if `rhs` is zero.
3784 ///
3785 /// # Examples
3786 ///
3787 /// ```
3788 /// #![feature(int_roundings)]
3789 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3790 /// ```
3791 #[unstable(feature = "int_roundings", issue = "88581")]
3792 #[must_use = "this returns the result of the operation, \
3793 without modifying the original"]
3794 #[inline(always)]
3795 #[track_caller]
3796 pub const fn div_floor(self, rhs: Self) -> Self {
3797 self / rhs
3798 }
3799
3800 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3801 ///
3802 /// # Panics
3803 ///
3804 /// This function will panic if `rhs` is zero.
3805 ///
3806 /// # Examples
3807 ///
3808 /// ```
3809 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3810 /// ```
3811 #[stable(feature = "int_roundings1", since = "1.73.0")]
3812 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3813 #[must_use = "this returns the result of the operation, \
3814 without modifying the original"]
3815 #[inline]
3816 #[track_caller]
3817 pub const fn div_ceil(self, rhs: Self) -> Self {
3818 let d = self / rhs;
3819 let r = self % rhs;
3820 if r > 0 {
3821 d + 1
3822 } else {
3823 d
3824 }
3825 }
3826
3827 /// Calculates the smallest value greater than or equal to `self` that
3828 /// is a multiple of `rhs`.
3829 ///
3830 /// # Panics
3831 ///
3832 /// This function will panic if `rhs` is zero.
3833 ///
3834 /// ## Overflow behavior
3835 ///
3836 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3837 /// mode) and wrap if overflow checks are disabled (default in release mode).
3838 ///
3839 /// # Examples
3840 ///
3841 /// ```
3842 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3843 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3844 /// ```
3845 #[stable(feature = "int_roundings1", since = "1.73.0")]
3846 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3847 #[must_use = "this returns the result of the operation, \
3848 without modifying the original"]
3849 #[inline]
3850 #[rustc_inherit_overflow_checks]
3851 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3852 match self % rhs {
3853 0 => self,
3854 r => self + (rhs - r)
3855 }
3856 }
3857
3858 /// Calculates the smallest value greater than or equal to `self` that
3859 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3860 /// operation would result in overflow.
3861 ///
3862 /// # Examples
3863 ///
3864 /// ```
3865 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3866 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3867 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3868 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3869 /// ```
3870 #[stable(feature = "int_roundings1", since = "1.73.0")]
3871 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3872 #[must_use = "this returns the result of the operation, \
3873 without modifying the original"]
3874 #[inline]
3875 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3876 match try_opt!(self.checked_rem(rhs)) {
3877 0 => Some(self),
3878 // rhs - r cannot overflow because r is smaller than rhs
3879 r => self.checked_add(rhs - r)
3880 }
3881 }
3882
3883 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3884 ///
3885 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3886 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3887 /// `n.is_multiple_of(0) == false`.
3888 ///
3889 /// # Examples
3890 ///
3891 /// ```
3892 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3893 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3894 ///
3895 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3896 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3897 /// ```
3898 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3899 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3900 #[must_use]
3901 #[inline]
3902 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3903 match rhs {
3904 0 => self == 0,
3905 _ => self % rhs == 0,
3906 }
3907 }
3908
3909 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3910 ///
3911 /// # Examples
3912 ///
3913 /// ```
3914 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3915 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3916 /// ```
3917 #[must_use]
3918 #[stable(feature = "rust1", since = "1.0.0")]
3919 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3920 #[inline(always)]
3921 pub const fn is_power_of_two(self) -> bool {
3922 self.count_ones() == 1
3923 }
3924
3925 // Returns one less than next power of two.
3926 // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
3927 //
3928 // 8u8.one_less_than_next_power_of_two() == 7
3929 // 6u8.one_less_than_next_power_of_two() == 7
3930 //
3931 // This method cannot overflow, as in the `next_power_of_two`
3932 // overflow cases it instead ends up returning the maximum value
3933 // of the type, and can return 0 for 0.
3934 #[inline]
3935 const fn one_less_than_next_power_of_two(self) -> Self {
3936 if self <= 1 { return 0; }
3937
3938 let p = self - 1;
3939 // SAFETY: Because `p > 0`, it cannot consist entirely of leading zeros.
3940 // That means the shift is always in-bounds, and some processors
3941 // (such as intel pre-haswell) have more efficient ctlz
3942 // intrinsics when the argument is non-zero.
3943 let z = unsafe { intrinsics::ctlz_nonzero(p) };
3944 <$SelfT>::MAX >> z
3945 }
3946
3947 /// Returns the smallest power of two greater than or equal to `self`.
3948 ///
3949 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3950 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3951 /// release mode (the only situation in which this method can return 0).
3952 ///
3953 /// # Examples
3954 ///
3955 /// ```
3956 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3957 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3958 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3959 /// ```
3960 #[stable(feature = "rust1", since = "1.0.0")]
3961 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3962 #[must_use = "this returns the result of the operation, \
3963 without modifying the original"]
3964 #[inline]
3965 #[rustc_inherit_overflow_checks]
3966 pub const fn next_power_of_two(self) -> Self {
3967 self.one_less_than_next_power_of_two() + 1
3968 }
3969
3970 /// Returns the smallest power of two greater than or equal to `self`. If
3971 /// the next power of two is greater than the type's maximum value,
3972 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3973 ///
3974 /// # Examples
3975 ///
3976 /// ```
3977 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3978 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3979 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3980 /// ```
3981 #[inline]
3982 #[stable(feature = "rust1", since = "1.0.0")]
3983 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3984 #[must_use = "this returns the result of the operation, \
3985 without modifying the original"]
3986 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3987 self.one_less_than_next_power_of_two().checked_add(1)
3988 }
3989
3990 /// Returns the smallest power of two greater than or equal to `n`. If
3991 /// the next power of two is greater than the type's maximum value,
3992 /// the return value is wrapped to `0`.
3993 ///
3994 /// # Examples
3995 ///
3996 /// ```
3997 /// #![feature(wrapping_next_power_of_two)]
3998 ///
3999 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
4000 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
4001 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
4002 /// ```
4003 #[inline]
4004 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
4005 reason = "needs decision on wrapping behavior")]
4006 #[must_use = "this returns the result of the operation, \
4007 without modifying the original"]
4008 pub const fn wrapping_next_power_of_two(self) -> Self {
4009 self.one_less_than_next_power_of_two().wrapping_add(1)
4010 }
4011
4012 /// Returns the memory representation of this integer as a byte array in
4013 /// big-endian (network) byte order.
4014 ///
4015 #[doc = $to_xe_bytes_doc]
4016 ///
4017 /// # Examples
4018 ///
4019 /// ```
4020 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
4021 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
4022 /// ```
4023 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4024 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4025 #[must_use = "this returns the result of the operation, \
4026 without modifying the original"]
4027 #[inline]
4028 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
4029 self.to_be().to_ne_bytes()
4030 }
4031
4032 /// Returns the memory representation of this integer as a byte array in
4033 /// little-endian byte order.
4034 ///
4035 #[doc = $to_xe_bytes_doc]
4036 ///
4037 /// # Examples
4038 ///
4039 /// ```
4040 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
4041 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
4042 /// ```
4043 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4044 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4045 #[must_use = "this returns the result of the operation, \
4046 without modifying the original"]
4047 #[inline]
4048 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
4049 self.to_le().to_ne_bytes()
4050 }
4051
4052 /// Returns the memory representation of this integer as a byte array in
4053 /// native byte order.
4054 ///
4055 /// As the target platform's native endianness is used, portable code
4056 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
4057 /// instead.
4058 ///
4059 #[doc = $to_xe_bytes_doc]
4060 ///
4061 /// [`to_be_bytes`]: Self::to_be_bytes
4062 /// [`to_le_bytes`]: Self::to_le_bytes
4063 ///
4064 /// # Examples
4065 ///
4066 /// ```
4067 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
4068 /// assert_eq!(
4069 /// bytes,
4070 /// if cfg!(target_endian = "big") {
4071 #[doc = concat!(" ", $be_bytes)]
4072 /// } else {
4073 #[doc = concat!(" ", $le_bytes)]
4074 /// }
4075 /// );
4076 /// ```
4077 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4078 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4079 #[must_use = "this returns the result of the operation, \
4080 without modifying the original"]
4081 #[allow(unnecessary_transmutes)]
4082 // SAFETY: const sound because integers are plain old datatypes so we can always
4083 // transmute them to arrays of bytes
4084 #[inline]
4085 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
4086 // SAFETY: integers are plain old datatypes so we can always transmute them to
4087 // arrays of bytes
4088 unsafe { mem::transmute(self) }
4089 }
4090
4091 /// Creates a native endian integer value from its representation
4092 /// as a byte array in big endian.
4093 ///
4094 #[doc = $from_xe_bytes_doc]
4095 ///
4096 /// # Examples
4097 ///
4098 /// ```
4099 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
4100 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4101 /// ```
4102 ///
4103 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4104 ///
4105 /// ```
4106 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4107 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4108 /// *input = rest;
4109 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4110 /// }
4111 /// ```
4112 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4113 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4114 #[must_use]
4115 #[inline]
4116 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4117 Self::from_be(Self::from_ne_bytes(bytes))
4118 }
4119
4120 /// Creates a native endian integer value from its representation
4121 /// as a byte array in little endian.
4122 ///
4123 #[doc = $from_xe_bytes_doc]
4124 ///
4125 /// # Examples
4126 ///
4127 /// ```
4128 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4129 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4130 /// ```
4131 ///
4132 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4133 ///
4134 /// ```
4135 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4136 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4137 /// *input = rest;
4138 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4139 /// }
4140 /// ```
4141 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4142 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4143 #[must_use]
4144 #[inline]
4145 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4146 Self::from_le(Self::from_ne_bytes(bytes))
4147 }
4148
4149 /// Creates a native endian integer value from its memory representation
4150 /// as a byte array in native endianness.
4151 ///
4152 /// As the target platform's native endianness is used, portable code
4153 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4154 /// appropriate instead.
4155 ///
4156 /// [`from_be_bytes`]: Self::from_be_bytes
4157 /// [`from_le_bytes`]: Self::from_le_bytes
4158 ///
4159 #[doc = $from_xe_bytes_doc]
4160 ///
4161 /// # Examples
4162 ///
4163 /// ```
4164 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4165 #[doc = concat!(" ", $be_bytes, "")]
4166 /// } else {
4167 #[doc = concat!(" ", $le_bytes, "")]
4168 /// });
4169 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4170 /// ```
4171 ///
4172 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4173 ///
4174 /// ```
4175 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4176 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4177 /// *input = rest;
4178 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4179 /// }
4180 /// ```
4181 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4182 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4183 #[allow(unnecessary_transmutes)]
4184 #[must_use]
4185 // SAFETY: const sound because integers are plain old datatypes so we can always
4186 // transmute to them
4187 #[inline]
4188 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4189 // SAFETY: integers are plain old datatypes so we can always transmute to them
4190 unsafe { mem::transmute(bytes) }
4191 }
4192
4193 /// New code should prefer to use
4194 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4195 ///
4196 /// Returns the smallest value that can be represented by this integer type.
4197 #[stable(feature = "rust1", since = "1.0.0")]
4198 #[rustc_promotable]
4199 #[inline(always)]
4200 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4201 #[deprecated(since = "1.99.0", note = "replaced by the `MIN` associated constant on this type")]
4202 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4203 pub const fn min_value() -> Self { Self::MIN }
4204
4205 /// New code should prefer to use
4206 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4207 ///
4208 /// Returns the largest value that can be represented by this integer type.
4209 #[stable(feature = "rust1", since = "1.0.0")]
4210 #[rustc_promotable]
4211 #[inline(always)]
4212 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4213 #[deprecated(since = "1.99.0", note = "replaced by the `MAX` associated constant on this type")]
4214 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4215 pub const fn max_value() -> Self { Self::MAX }
4216
4217 /// Truncate an integer to an integer of the same size or smaller, preserving the least
4218 /// significant bits.
4219 ///
4220 /// # Examples
4221 ///
4222 /// ```
4223 /// #![feature(integer_widen_truncate)]
4224 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".truncate());")]
4225 /// assert_eq!(120u8, 376u32.truncate());
4226 /// ```
4227 #[must_use = "this returns the truncated value and does not modify the original"]
4228 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4229 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4230 #[inline]
4231 pub const fn truncate<Target>(self) -> Target
4232 where Self: [const] traits::TruncateTarget<Target>
4233 {
4234 traits::TruncateTarget::internal_truncate(self)
4235 }
4236
4237 /// Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds
4238 /// instead of truncating.
4239 ///
4240 /// # Examples
4241 ///
4242 /// ```
4243 /// #![feature(integer_widen_truncate)]
4244 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".saturating_truncate());")]
4245 /// assert_eq!(255u8, 376u32.saturating_truncate());
4246 /// ```
4247 #[must_use = "this returns the truncated value and does not modify the original"]
4248 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4249 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4250 #[inline]
4251 pub const fn saturating_truncate<Target>(self) -> Target
4252 where Self: [const] traits::TruncateTarget<Target>
4253 {
4254 traits::TruncateTarget::internal_saturating_truncate(self)
4255 }
4256
4257 /// Truncate an integer to an integer of the same size or smaller, returning `None` if the value
4258 /// is outside the bounds of the smaller type.
4259 ///
4260 /// # Examples
4261 ///
4262 /// ```
4263 /// #![feature(integer_widen_truncate)]
4264 #[doc = concat!("assert_eq!(Some(120u8), 120", stringify!($SelfT), ".checked_truncate());")]
4265 /// assert_eq!(None, 376u32.checked_truncate::<u8>());
4266 /// ```
4267 #[must_use = "this returns the truncated value and does not modify the original"]
4268 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4269 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4270 #[inline]
4271 pub const fn checked_truncate<Target>(self) -> Option<Target>
4272 where Self: [const] traits::TruncateTarget<Target>
4273 {
4274 traits::TruncateTarget::internal_checked_truncate(self)
4275 }
4276
4277 /// Widen to an integer of the same size or larger, preserving its value.
4278 ///
4279 /// # Examples
4280 ///
4281 /// ```
4282 /// #![feature(integer_widen_truncate)]
4283 #[doc = concat!("assert_eq!(120u128, 120u8.widen());")]
4284 /// ```
4285 #[must_use = "this returns the widened value and does not modify the original"]
4286 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4287 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4288 #[inline]
4289 pub const fn widen<Target>(self) -> Target
4290 where Self: [const] traits::WidenTarget<Target>
4291 {
4292 traits::WidenTarget::internal_widen(self)
4293 }
4294
4295 /// Converts `self` to the target integer type, saturating at the numeric
4296 /// bounds instead of overflowing.
4297 ///
4298 /// # Examples
4299 ///
4300 /// ```
4301 /// #![feature(integer_casts)]
4302 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4303 #[doc = concat!("assert_eq!(127i8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4304 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".saturating_cast());")]
4305 /// ```
4306 #[must_use = "this returns the cast result and does not modify the original"]
4307 #[unstable(feature = "integer_casts", issue = "157388")]
4308 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4309 #[inline(always)]
4310 pub const fn saturating_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4311 T::saturating_cast_from(self)
4312 }
4313
4314 /// Converts `self` to the target integer type, wrapping around at the
4315 /// boundary of the target type.
4316 ///
4317 /// # Examples
4318 ///
4319 /// ```
4320 /// #![feature(integer_casts)]
4321 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4322 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".wrapping_cast());")]
4323 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX as i8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4324 /// ```
4325 #[must_use = "this returns the cast result and does not modify the original"]
4326 #[unstable(feature = "integer_casts", issue = "157388")]
4327 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4328 #[inline(always)]
4329 pub const fn wrapping_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4330 T::wrapping_cast_from(self)
4331 }
4332
4333 /// Converts `self` to the target integer type, returning `None` if the value
4334 /// is not representable by the target type.
4335 ///
4336 /// # Examples
4337 ///
4338 /// ```
4339 /// #![feature(integer_casts)]
4340 #[doc = concat!("assert_eq!(Some(42u8), 42", stringify!($SelfT), ".checked_cast());")]
4341 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_cast::<i8>(), None);")]
4342 /// ```
4343 #[must_use = "this returns the cast result and does not modify the original"]
4344 #[unstable(feature = "integer_casts", issue = "157388")]
4345 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4346 #[inline(always)]
4347 pub const fn checked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> Option<T> {
4348 T::checked_cast_from(self)
4349 }
4350
4351 /// Converts `self` to the target integer type, panicking if the value
4352 /// is not representable by the target type.
4353 ///
4354 /// # Panics
4355 ///
4356 /// This function will panic if the value is not representable by the target type.
4357 ///
4358 /// # Examples
4359 ///
4360 /// ```
4361 /// #![feature(integer_casts)]
4362 #[doc = concat!("assert_eq!(42u8, 42", stringify!($SelfT), ".strict_cast());")]
4363 /// ```
4364 ///
4365 /// The following will panic:
4366 ///
4367 /// ```should_panic
4368 /// #![feature(integer_casts)]
4369 #[doc = concat!("let _ = 128", stringify!($SelfT), ".strict_cast::<i8>();")]
4370 /// ```
4371 #[must_use = "this returns the cast result and does not modify the original"]
4372 #[unstable(feature = "integer_casts", issue = "157388")]
4373 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4374 #[inline(always)]
4375 #[track_caller]
4376 pub const fn strict_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4377 T::strict_cast_from(self)
4378 }
4379
4380 /// Converts `self` to the target integer type, assuming the value is
4381 /// representable by the target type.
4382 ///
4383 /// # Safety
4384 ///
4385 /// This results in undefined behavior if the integer value of `self` is bigger than `T::MAX`,
4386 /// or smaller than `T::MIN`, where `T` is the target type.
4387 #[must_use = "this returns the cast result and does not modify the original"]
4388 #[unstable(feature = "integer_casts", issue = "157388")]
4389 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4390 #[inline(always)]
4391 pub const unsafe fn unchecked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4392 assert_unsafe_precondition!(
4393 check_language_ub,
4394 concat!(stringify!($SelfT), "::unchecked_cast must fit in the target type"),
4395 (
4396 // Check has to be performed up-front because it depends on generic T.
4397 in_bounds: bool = {
4398 let cast_val = self.checked_cast::<T>();
4399 let ret = cast_val.is_some();
4400 core::mem::forget(cast_val); // We don't have const Drop, but we know it's an int.
4401 ret
4402 },
4403 ) => in_bounds,
4404 );
4405
4406 // SAFETY: this is guaranteed to be safe by the caller.
4407 unsafe { T::unchecked_cast_from(self) }
4408 }
4409 }
4410}