cmov

Conditional move CPU intrinsics which are guaranteed on major platforms (ARM32/ARM64, x86/x86_64, RISC-V) to execute in constant-time and not be rewritten as branches by the compiler. Provides wrappers for the CMOV family of instructions on x86/x86_64 and CSEL on AArch64, along with a portable "best-effort" pure Rust fallback implementation.

0.5.4 54M downloads/mo #1168 most downloaded on crates.io RustCrypto/utils

What this package is like to depend on

Last release 2 months ago

28 May 2026

Ships unpredictably

gaps range from 8 days to 1.9 years

Nearly every release is documented

notes for 6 of 6 stable releases

12 versions withdrawn

withdrawn after publishing

5 years old

21 releases · first in 2022

15 releases in the last 12 months

see the full history below

Release timeline

21 releases · Feb 2022 to May 2026

2023 2024 2025 2026

Release Pre-release Withdrawn

Releases

latest 21

0.5.4 28 May 2026
Release notes
Security
- Fix GHSA-3rjw-m598-pq24]: Cmov/CmovEq on aarch64 can produce
  wrong results if high-bits of registers are set (dba6c35)
Open source →
Release notes
Security
- Fix GHSA-3rjw-m598-pq24: Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set (dba6c355)
Open source →
0.5.3 02 Apr 2026
Release notes
Added
- Impl Cmov/CmovEq for NonZeroUsize/NonZeroIsize (#1415)
Changed
- Avoid using asm! under cfg(miri) (#1436)
Open source →
Release notes
Added
- Impl Cmov/CmovEq for NonZeroUsize/NonZeroIsize (#1415)
Changed
- Avoid using asm! under cfg(miri) (#1436)
Open source →
0.5.2 20 Jan 2026
Release notes
Fixed
- Cmov impl for isize/usize (#1412)
Open source →
0.5.1 19 Jan 2026 withdrawn
Release notes
Added
- riscv32 optimised mask generation (#1396)
- riscv64 optimised mask generation (#1397)
- Support for core::num::NonZero* and core::cmp::Ordering (#1404)
Open source →
0.5.0 18 Jan 2026 withdrawn
Release notes
Added
- Optimized CmovEq for [u8] (#1356)
- Optimized CmovEq for [u16] (#1370)
- Impl Cmov/CmovEq for slices of unsigned integers (#1370, #1372)
- Impl Cmov/CmovEq for slices of signed integers (#1373)
- Impl Cmov/CmovEq for isize/usize (#1375)
Changed
- Impls of Cmov/CmovEq for [T; N] are now bounded on [T]: Cmov(Eq) (#1372)
Removed
- Generic impl of CmovEq for [T] where T: CmovEq in favor of specialized impls (#1356)
Open source →
0.5.0-pre.2 17 Jan 2026 pre-release

Nothing published for this version
0.5.0-pre.1 17 Jan 2026 pre-release

Nothing published for this version
0.5.0-pre.0 16 Jan 2026 pre-release

Nothing published for this version
0.4.6 16 Jan 2026
Release notes
Added
- Optimized Cmov for [u8; N] (#1350)
- Optimized CmovEq for [u8; N] (#1353)
- Optimized Cmov for [u8] (#1354)
Fixed
- Provided Cmov::cmovz impl (#1351)
Open source →
0.4.5 15 Jan 2026
Release notes
Changed
- Introduce small ARM32 asm! optimization which also guarantees constant-time operation (#1336, #1346)
Open source →
0.4.4 14 Jan 2026
Release notes
Security
- Fix non-constant-time assembly being emitted from portable backend on thumbv6m-none-eabi (#1332)
Open source →
0.4.3 28 Dec 2025 withdrawn
Release notes
Fixed
- aarch64 ASM bug (#1299)
- Truncation bug in portable implementation (#1300)
Open source →
0.4.2 27 Dec 2025 withdrawn
Release notes
Added
- Signed integer support (#1280)
Open source →
0.4.1 20 Dec 2025 withdrawn
Release notes
Changed
- Use black_box in portable impl (#1255)
Open source →
0.4.0 10 Sep 2025 withdrawn
Release notes
Changed
- Edition changed to 2024 and MSRV bumped to 1.85 (#1149)
Open source →
0.3.1 14 Oct 2023 withdrawn
Release notes
Added
- CmovEq impl for slices (#954)
Changed
- Use #[inline] instead of #[inline(always)] (#924)
- CmovEq now invokes XOR within the ASM block (#925)
Open source →
0.3.0 03 Apr 2023 withdrawn
Release notes
Added
- miri support by forcing the portable backend (#864)
- Constant-time equality comparisons (#873)
Changed
- Make Cmov::cmovz a provided method (#871)
Fixed
- Builds on x86 (32-bit) targets (#863)
Open source →
0.2.0 26 Feb 2023 withdrawn
Release notes
Added
- Condition alias for u8 (#830)
Changed
- Redesigned trait-based API (#830)
  - Built around a Cmov trait
  - Trait is impl'd for u8, u16, u32, u64, u128
  - Accepts a Condition (i.e. u8) as a predicate
- MSRV 1.60 (#839)
Open source →
0.1.1 02 Mar 2022 withdrawn
Release notes
Added
- cmovz/cmovnz-alike support for AArch64 targets (#744)
Open source →
0.1.0 27 Feb 2022 withdrawn
Release notes
- Initial release
Open source →
0.0.0 11 Feb 2022 withdrawn

Nothing published for this version

cmov

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