Crate atomic_polyfill

⚠️ THIS CRATE IS DEPRECATED ⚠️

Use portable-atomic instead. It supports many more architectures and more efficient ways of emulating atomics.

portable-atomic with the critical-section feature is a drop-in replacement. It uses the critical-section crate to ensure locking, just like atomic-polyfill.

However, if your chip is single-core, you might want to enable the unsafe-assume-single-core feature instead. It makes portable-atomic emulate atomics by disabling interrupts. It is faster than using a critical-section implementation that disables interrupts, because it allows disabling them only on CAS operations, not in load/store operations.

If you’re writing a library, add a dependency on portable-atomic but do NOT enable any feature on it. Let the end user of your library enable the right features for their target. If you enable features, you’re taking their choice away.

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atomic-polyfill

This crate polyfills atomics on targets where they’re not available, using critical sections. It is intended to be a drop-in replacement for core::sync::atomic.

There are two “levels” of polyfilling:

• Native: No polyfilling is performed, the native core::sync::atomic::AtomicXX is reexported.
• Full: Both load/store and compare-and-set operations are polyfilled.

Polyfilling requires a critical-section implementation for the current target. Check the critical-section README for details.

Target support

The right polyfill level is automatically picked based on the target and the atomic width:

Target	Level	Level for u64/i64
thumbv4t	Full	Full
thumbv6m	Full	Full
thumbv7*, thumbv8*	Native	Full
riscv32imc	Full	Full
riscv32imac	Native	Full
xtensa-*-espidf	Native	Native
xtensa-esp32-*	Native	Full
xtensa-esp32s2-*	Full	Full
xtensa-esp32s3-*	Native	Full
xtensa-esp8266-*	Full	Full
AVR	Full	Full

For targets not listed above, atomic-polyfill assumes nothing and reexports core::sync::atomic::*. No polyfilling is done. PRs for polyfilling more targets are welcome :)

Minimum Supported Rust Version (MSRV)

MSRV is currently Rust 1.54. MSRV may be upgraded at any new patch release as long as latest stable Rust is supported.

License

This work is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Structs

• AtomicBool
  A boolean type which can be safely shared between threads.
• AtomicI8
  An integer type which can be safely shared between threads.
• AtomicI16
  An integer type which can be safely shared between threads.
• AtomicI32
  An integer type which can be safely shared between threads.
• AtomicI64
  An integer type which can be safely shared between threads.
• AtomicIsize
  An integer type which can be safely shared between threads.
• AtomicPtr
  A raw pointer type which can be safely shared between threads.
• AtomicU8
  An integer type which can be safely shared between threads.
• AtomicU16
  An integer type which can be safely shared between threads.
• AtomicU32
  An integer type which can be safely shared between threads.
• AtomicU64
  An integer type which can be safely shared between threads.
• AtomicUsize
  An integer type which can be safely shared between threads.

Enums

• Ordering
  Atomic memory orderings

Constants

• ATOMIC_I8_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_I16_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_I32_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_I64_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_U8_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_U16_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_U32_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_U64_INITDeprecatedExperimental
  An atomic integer initialized to 0.
• ATOMIC_BOOL_INITDeprecated
  An AtomicBool initialized to false.
• ATOMIC_ISIZE_INITDeprecated
  An atomic integer initialized to 0.
• ATOMIC_USIZE_INITDeprecated
  An atomic integer initialized to 0.

Functions

• compiler_fence
  A compiler memory fence.
• fence
  An atomic fence.
• spin_loop_hintDeprecated
  Signals the processor that it is inside a busy-wait spin-loop (“spin lock”).