add NonZero<uN>::isqrt · model-checking/verify-rust-std@9348998 (original) (raw)
`@@ -3,6 +3,7 @@
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`use crate::cmp::Ordering;
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`use crate::fmt;
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`use crate::hash::{Hash, Hasher};
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use crate::hint;
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`use crate::intrinsics;
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`use crate:📑:{Freeze, StructuralPartialEq};
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`use crate::ops::{BitOr, BitOrAssign, Div, DivAssign, Neg, Rem, RemAssign};
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`@@ -604,7 +605,6 @@ macro_rules! nonzero_integer {
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`}
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` nonzero_integer_signedness_dependent_methods! {
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``
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Self = $Ty,
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`Primitive = signednesssignedness signednessInt,
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`UnsignedPrimitive = $Uint,
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`}
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`@@ -823,7 +823,7 @@ macro_rules! nonzero_integer {
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`}
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`}
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``
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nonzero_integer_signedness_dependent_impls!($Ty signednesssignedness signednessInt);
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nonzero_integer_signedness_dependent_impls!($signedness $Int);
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`};
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``
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`(Self = Ty:ident,Primitive=unsignedTy:ident, Primitive = unsigned Ty:ident,Primitive=unsignedInt:ident $(,)?) => {
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`@@ -849,7 +849,7 @@ macro_rules! nonzero_integer {
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``
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`macro_rules! nonzero_integer_signedness_dependent_impls {
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`// Impls for unsigned nonzero types only.
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``
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($Ty:ident unsigned $Int:ty) => {
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(unsigned $Int:ty) => {
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` #[stable(feature = "nonzero_div", since = "1.51.0")]
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`impl Div<NonZero<$Int>> for $Int {
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`type Output = $Int;
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`@@ -897,7 +897,7 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
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`}
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`};
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`// Impls for signed nonzero types only.
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``
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($Ty:ident signed $Int:ty) => {
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(signed $Int:ty) => {
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` #[stable(feature = "signed_nonzero_neg", since = "1.71.0")]
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`impl Neg for NonZero<$Int> {
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`type Output = Self;
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`@@ -918,7 +918,6 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
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`macro_rules! nonzero_integer_signedness_dependent_methods {
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`// Associated items for unsigned nonzero types only.
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`(
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``
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Self = $Ty:ident,
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`Primitive = unsigned $Int:ident,
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`UnsignedPrimitive = $Uint:ty,
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`) => {
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`@@ -1224,11 +1223,60 @@ macro_rules! nonzero_integer_signedness_dependent_methods {
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` intrinsics::ctpop(self.get()) < 2
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`}
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/// Returns the square root of the number, rounded down.
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///
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/// # Examples
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///
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/// Basic usage:
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/// ```
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/// #![feature(isqrt)]
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/// # use std::num::NonZero;
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/// #
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/// # fn main() { test().unwrap(); }
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/// # fn test() -> Option<()> {
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#[doc = concat!("let ten = NonZero::new(10", stringify!($Int), ")?;")]
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#[doc = concat!("let three = NonZero::new(3", stringify!($Int), ")?;")]
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///
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/// assert_eq!(ten.isqrt(), three);
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/// # Some(())
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/// # }
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#[unstable(feature = "isqrt", issue = "116226")]
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#[rustc_const_unstable(feature = "isqrt", issue = "116226")]
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#[must_use = "this returns the result of the operation, \
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without modifying the original"]
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#[inline]
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pub const fn isqrt(self) -> Self {
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// The algorithm is based on the one presented in
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// https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Binary_numeral_system_(base_2)
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// which cites as source the following C code:
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// https://web.archive.org/web/20120306040058/http://medialab.freaknet.org/martin/src/sqrt/sqrt.c.
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let mut op = self.get();
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let mut res = 0;
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let mut one = 1 << (self.ilog2() & !1);
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while one != 0 {
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if op >= res + one {
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op -= res + one;
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res = (res >> 1) + one;
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} else {
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res >>= 1;
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}
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one >>= 2;
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}
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``
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// SAFETY: The result fits in an integer with half as many bits.
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// Inform the optimizer about it.
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unsafe { hint::assert_unchecked(res < 1 << (Self::BITS / 2)) };
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``
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// SAFETY: The result is positive.
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unsafe { Self::new_unchecked(res) }
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}
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`};
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`// Associated items for signed nonzero types only.
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`(
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`-
Self = $Ty:ident,
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`Primitive = signed $Int:ident,
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`UnsignedPrimitive = $Uint:ty,
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`) => {
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