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Use 64-bit words on wasm targets #973

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4 changes: 2 additions & 2 deletions src/const_choice.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,13 +25,13 @@ impl ConstChoice {
}

#[inline]
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
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I wonder if there's some way to make an alias for that so that we could only spell out this condition once.

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I also considered it, but I believe it'd require adding a build script to set a cfg for the desired word size. I didn't want to take that step when we have this single exception at this time.

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@tarcieri tarcieri Oct 6, 2025 •
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I was intending to solve this with the vaporwarecpubits crate (which as it were uses a build script to set a cfg attribute)

RustCrypto/utils#826

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@tarcieri tarcieri Oct 6, 2025 •
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I didn't want to take that step when we have this single exception at this time.

IMO this isn’t worth doing in a way that can’t be applied easily and in a DRY manner for multiple targets.

As noted in RustCrypto/utils#824 this same sort of 64-bit promotion should be applied to ARMv7 targets

pub(crate) const fn as_u64_mask(&self) -> u64 {
((self.0 as u64) << 32) | (self.0 as u64)
}

#[inline]
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub(crate) const fn as_u64_mask(&self) -> u64 {
self.0
}
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4 changes: 2 additions & 2 deletions src/int.rs
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Expand Up @@ -373,14 +373,14 @@ mod tests {

use crate::{ConstChoice, I128, U128};

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
#[test]
fn as_words() {
let n = I128::from_be_hex("AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDD");
assert_eq!(n.as_words(), &[0xCCCCCCCCDDDDDDDD, 0xAAAAAAAABBBBBBBB]);
}

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
#[test]
fn as_words_mut() {
let mut n = I128::from_be_hex("AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDD");
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8 changes: 4 additions & 4 deletions src/int/from.rs
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Expand Up @@ -26,14 +26,14 @@ impl<const LIMBS: usize> Int<LIMBS> {

/// Create a [`Int`] from an `i64` (const-friendly)
// TODO(tarcieri): replace with `const impl From<i64>` when stable
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
pub const fn from_i64(n: i64) -> Self {
Uint::<{ I64::LIMBS }>::from_u64(n as u64).as_int().resize()
}

/// Create a [`Int`] from an `i64` (const-friendly)
// TODO(tarcieri): replace with `const impl From<i64>` when stable
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub const fn from_i64(n: i64) -> Self {
assert!(LIMBS >= 1, "number of limbs must be greater than zero");
Uint::new([Limb(n as Word)]).as_int().resize()
Expand Down Expand Up @@ -108,9 +108,9 @@ impl<const LIMBS: usize, const LIMBS2: usize> From<&Int<LIMBS>> for Int<LIMBS2>

#[cfg(test)]
mod tests {
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
use crate::I64 as IntEx;
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
use crate::I128 as IntEx;
use crate::{I128, Limb};

Expand Down
28 changes: 14 additions & 14 deletions src/int/types.rs
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Expand Up @@ -3,58 +3,58 @@

use crate::Int;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I64 = Int<1>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I128 = Int<2>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I256 = Int<4>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I512 = Int<8>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I1024 = Int<16>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I2048 = Int<32>;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
/// Signed bit integer.
pub type I4096 = Int<64>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I64 = Int<2>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I128 = Int<4>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I256 = Int<8>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I512 = Int<16>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I1024 = Int<32>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I2048 = Int<64>;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
/// Signed bit integer.
pub type I4096 = Int<128>;
20 changes: 10 additions & 10 deletions src/limb.rs
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Expand Up @@ -34,23 +34,23 @@ compile_error!("this crate builds on 32-bit and 64-bit platforms only");
//

/// Inner integer type that the [`Limb`] newtype wraps.
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
pub type Word = u32;

/// Unsigned wide integer type: double the width of [`Word`].
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
pub type WideWord = u64;

//
// 64-bit definitions
//

/// Unsigned integer type that the [`Limb`] newtype wraps.
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub type Word = u64;

/// Wide integer type: double the width of [`Word`].
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub type WideWord = u128;

/// Big integers are represented as an array/vector of smaller CPU word-size integers called
Expand Down Expand Up @@ -80,19 +80,19 @@ impl Limb {
// 32-bit

/// Size of the inner integer in bits.
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
pub const BITS: u32 = 32;
/// Size of the inner integer in bytes.
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
pub const BYTES: usize = 4;

// 64-bit

/// Size of the inner integer in bits.
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub const BITS: u32 = 64;
/// Size of the inner integer in bytes.
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub const BYTES: usize = 8;

/// `floor(log2(Self::BITS))`.
Expand Down Expand Up @@ -239,10 +239,10 @@ mod tests {
#[cfg(feature = "alloc")]
#[test]
fn debug() {
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
assert_eq!(format!("{:?}", Limb(42)), "Limb(0x0000002A)");

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
assert_eq!(format!("{:?}", Limb(42)), "Limb(0x000000000000002A)");
}
}
8 changes: 4 additions & 4 deletions src/limb/encoding.rs
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Expand Up @@ -4,9 +4,9 @@ use super::{Limb, Word};
use crate::Encoding;

impl Encoding for Limb {
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
type Repr = [u8; 4];
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
type Repr = [u8; 8];

#[inline]
Expand Down Expand Up @@ -65,10 +65,10 @@ impl Limb {
mod test {
use super::*;

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
const LIMB: Limb = Limb(0x7654_3210);

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
const LIMB: Limb = Limb(0xFEDCBA9876543210);

#[test]
Expand Down
4 changes: 2 additions & 2 deletions src/limb/from.rs
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Expand Up @@ -24,7 +24,7 @@ impl Limb {

/// Create a [`Limb`] from a `u64` integer (const-friendly)
// TODO(tarcieri): replace with `const impl From<u64>` when stable
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub const fn from_u64(n: u64) -> Self {
Limb(n)
}
Expand All @@ -51,7 +51,7 @@ impl From<u32> for Limb {
}
}

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
impl From<u64> for Limb {
#[inline]
fn from(n: u64) -> Limb {
Expand Down
4 changes: 2 additions & 2 deletions src/limb/mul.rs
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Expand Up @@ -129,14 +129,14 @@ mod tests {
use super::{CheckedMul, Limb};

#[test]
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
fn checked_mul_ok() {
let n = Limb::from_u16(0xffff);
assert_eq!(n.checked_mul(&n).unwrap(), Limb::from_u32(0xfffe_0001));
}

#[test]
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
fn checked_mul_ok() {
let n = Limb::from_u32(0xffff_ffff);
assert_eq!(
Expand Down
4 changes: 2 additions & 2 deletions src/limb/rand.rs
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Expand Up @@ -7,9 +7,9 @@ use subtle::ConstantTimeLess;

impl Random for Limb {
fn try_random<R: TryRngCore + ?Sized>(rng: &mut R) -> Result<Self, R::Error> {
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
let val = rng.try_next_u32()?;
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
let val = rng.try_next_u64()?;

Ok(Self(val))
Expand Down
4 changes: 2 additions & 2 deletions src/macros.rs
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Expand Up @@ -11,7 +11,7 @@ macro_rules! nlimbs {

#[cfg(test)]
mod tests {
#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
#[test]
fn nlimbs_for_bits_macro() {
assert_eq!(nlimbs!(64), 2);
Expand All @@ -20,7 +20,7 @@ mod tests {
assert_eq!(nlimbs!(256), 8);
}

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
#[test]
fn nlimbs_for_bits_macro() {
assert_eq!(nlimbs!(64), 1);
Expand Down
4 changes: 2 additions & 2 deletions src/non_zero.rs
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Expand Up @@ -179,7 +179,7 @@ impl NonZero<Limb> {

/// Create a [`NonZero<Limb>`] from a [`NonZeroU64`] (const-friendly)
// TODO(tarcieri): replace with `const impl From<NonZeroU64>` when stable
#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
pub const fn from_u64(n: NonZeroU64) -> Self {
Self(Limb::from_u64(n.get()))
}
Expand Down Expand Up @@ -367,7 +367,7 @@ impl From<NonZeroU32> for NonZero<Limb> {
}
}

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
impl From<NonZeroU64> for NonZero<Limb> {
fn from(integer: NonZeroU64) -> Self {
Self::from_u64(integer)
Expand Down
8 changes: 4 additions & 4 deletions src/uint.rs
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Expand Up @@ -461,13 +461,13 @@ impl_uint_aliases! {
(U32768, 32768, "32768-bit")
}

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
impl_uint_aliases! {
(U224, 224, "224-bit"), // For NIST P-224
(U544, 544, "544-bit") // For NIST P-521
}

#[cfg(target_pointer_width = "32")]
#[cfg(all(target_pointer_width = "32", not(target_family = "wasm")))]
impl_uint_concat_split_even! {
U64,
}
Expand Down Expand Up @@ -533,14 +533,14 @@ mod tests {
#[cfg(feature = "alloc")]
use alloc::format;

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
#[test]
fn as_words() {
let n = U128::from_be_hex("AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDD");
assert_eq!(n.as_words(), &[0xCCCCCCCCDDDDDDDD, 0xAAAAAAAABBBBBBBB]);
}

#[cfg(target_pointer_width = "64")]
#[cfg(any(target_pointer_width = "64", target_family = "wasm"))]
#[test]
fn as_words_mut() {
let mut n = U128::from_be_hex("AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDD");
Expand Down
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