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isqrt: remove duplication by delegating to unsigned integers

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This commit is contained in:
Federico Stra 2023-09-26 15:44:28 +02:00
parent 1b34f1c6b2
commit 68f0b475c7
2 changed files with 12 additions and 40 deletions
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50
library/core/src/num/int_macros.rs
View File

@ -915,26 +915,10 @@ macro_rules! int_impl {
#[inline]
pub const fn checked_isqrt(self) -> Option<Self> {
if self < 0 {
return None;
} else if self < 2 {
return Some(self);
None
} else {
Some((self as $UnsignedT).isqrt() as Self)
}
let mut x: Self = self;
let mut c: Self = 0;
let mut d: Self = 1 << (self.ilog2() & !1);
while (d != 0) {
if x >= c + d {
x -= c + d;
c = (c >> 1) + d;
} else {
c >>= 1;
}
d >>= 2;
}
return Some(c);
}
/// Saturating integer addition. Computes `self + rhs`, saturating at the numeric
@ -2118,27 +2102,15 @@ macro_rules! int_impl {
without modifying the original"]
#[inline]
pub const fn isqrt(self) -> Self {
if self < 0 {
panic!("argument of integer square root must be non-negative")
} else if self < 2 {
return self;
// I would like to implement it as
// ```
// self.checked_isqrt().expect("argument of integer square root must be non-negative")
// ```
// but `expect` is not yet stable as a `const fn`.
match self.checked_isqrt() {
Some(sqrt) => sqrt,
None => panic!("argument of integer square root must be non-negative"),
}
let mut x: Self = self;
let mut c: Self = 0;
let mut d: Self = 1 << (self.ilog2() & !1);
while (d != 0) {
if x >= c + d {
x -= c + d;
c = (c >> 1) + d;
} else {
c >>= 1;
}
d >>= 2;
}
return c;
}
/// Calculates the quotient of Euclidean division of `self` by `rhs`.

2
library/core/src/num/uint_macros.rs
View File

@ -2011,7 +2011,7 @@ macro_rules! uint_impl {
d >>= 2;
}
return c;
c
}
/// Performs Euclidean division.