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Optimize isqrt #2108

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2 changes: 2 additions & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -47,13 +47,15 @@ and this project adheres to
- cosmwasm-schema-derive: Improve emitted error messages ([#2063])
- cosmwasm-schema: `#[cw_serde]` now doesn't add `#[serde(deny_unknown_fields)]`
to the expanded code anymore ([#2080])
- cosmwasm-std: Improve performance of `Uint{64,128,256,512}::isqrt` ([#2108])

[#2044]: https://github.com/CosmWasm/cosmwasm/pull/2044
[#2051]: https://github.com/CosmWasm/cosmwasm/pull/2051
[#2059]: https://github.com/CosmWasm/cosmwasm/pull/2059
[#2063]: https://github.com/CosmWasm/cosmwasm/pull/2063
[#2070]: https://github.com/CosmWasm/cosmwasm/pull/2070
[#2080]: https://github.com/CosmWasm/cosmwasm/pull/2080
[#2108]: https://github.com/CosmWasm/cosmwasm/pull/2108

## [2.0.1] - 2024-04-03

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53 changes: 38 additions & 15 deletions packages/core/src/math/isqrt.rs
Original file line number Diff line number Diff line change
Expand Up @@ -15,17 +15,22 @@ where
I: Unsigned
+ ops::Add<I, Output = I>
+ ops::Div<I, Output = I>
+ ops::Shl<u32, Output = I>
+ ops::Shr<u32, Output = I>
+ cmp::PartialOrd
+ Copy
+ From<u8>,
+ Copy,
{
/// Algorithm adapted from
/// [Wikipedia](https://en.wikipedia.org/wiki/Integer_square_root#Example_implementation_in_C).
fn isqrt(self) -> Self {
let mut x0 = self >> 1;
// sqrt(0) = 0, sqrt(1) = 1
if self <= Self::ONE {
return self;
}

let mut x0 = Self::ONE << ((self.log_2() / 2) + 1);

if x0 > 0.into() {
if x0 > Self::ZERO {
let mut x1 = (x0 + self / x0) >> 1;

while x1 < x0 {
Expand All @@ -40,17 +45,35 @@ where
}

/// Marker trait for types that represent unsigned integers.
pub trait Unsigned {}
impl Unsigned for u8 {}
impl Unsigned for u16 {}
impl Unsigned for u32 {}
impl Unsigned for u64 {}
impl Unsigned for u128 {}
impl Unsigned for Uint64 {}
impl Unsigned for Uint128 {}
impl Unsigned for Uint256 {}
impl Unsigned for Uint512 {}
impl Unsigned for usize {}
pub trait Unsigned {
const ZERO: Self;
const ONE: Self;

fn log_2(self) -> u32;
}
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macro_rules! impl_unsigned {
($type:ty, $zero:expr, $one:expr) => {
impl Unsigned for $type {
const ZERO: Self = $zero;
const ONE: Self = $one;

fn log_2(self) -> u32 {
self.ilog2()
}
}
};
}
impl_unsigned!(u8, 0, 1);
impl_unsigned!(u16, 0, 1);
impl_unsigned!(u32, 0, 1);
impl_unsigned!(u64, 0, 1);
impl_unsigned!(u128, 0, 1);
impl_unsigned!(usize, 0, 1);
impl_unsigned!(Uint64, Self::zero(), Self::one());
impl_unsigned!(Uint128, Self::zero(), Self::one());
impl_unsigned!(Uint256, Self::zero(), Self::one());
impl_unsigned!(Uint512, Self::zero(), Self::one());

#[cfg(test)]
mod tests {
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10 changes: 10 additions & 0 deletions packages/core/src/math/uint128.rs
Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,16 @@ impl Uint128 {
self.0.pow(exp).into()
}

/// Returns the base 2 logarithm of the number, rounded down.
///
/// # Panics
///
/// This function will panic if `self` is zero.
#[must_use = "this returns the result of the operation, without modifying the original"]
pub fn ilog2(self) -> u32 {
self.0.checked_ilog2().unwrap()
}

/// Returns `self * numerator / denominator`.
///
/// Due to the nature of the integer division involved, the result is always floored.
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10 changes: 10 additions & 0 deletions packages/core/src/math/uint256.rs
Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,16 @@ impl Uint256 {
Self(self.0.pow(exp))
}

/// Returns the base 2 logarithm of the number, rounded down.
///
/// # Panics
///
/// This function will panic if `self` is zero.
#[must_use = "this returns the result of the operation, without modifying the original"]
pub fn ilog2(self) -> u32 {
self.0.checked_ilog2().unwrap()
}

/// Returns `self * numerator / denominator`.
///
/// Due to the nature of the integer division involved, the result is always floored.
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10 changes: 10 additions & 0 deletions packages/core/src/math/uint512.rs
Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,16 @@ impl Uint512 {
Self(self.0.pow(exp))
}

/// Returns the base 2 logarithm of the number, rounded down.
///
/// # Panics
///
/// This function will panic if `self` is zero.
#[must_use = "this returns the result of the operation, without modifying the original"]
pub fn ilog2(self) -> u32 {
self.0.checked_ilog2().unwrap()
}

pub fn checked_add(self, other: Self) -> Result<Self, OverflowError> {
self.0
.checked_add(other.0)
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10 changes: 10 additions & 0 deletions packages/core/src/math/uint64.rs
Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,16 @@ impl Uint64 {
self.0.pow(exp).into()
}

/// Returns the base 2 logarithm of the number, rounded down.
///
/// # Panics
///
/// This function will panic if `self` is zero.
#[must_use = "this returns the result of the operation, without modifying the original"]
pub fn ilog2(self) -> u32 {
self.0.checked_ilog2().unwrap()
}

/// Returns `self * numerator / denominator`.
///
/// Due to the nature of the integer division involved, the result is always floored.
Expand Down