2018-07-12 00:44:28 -05:00
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# `libm`
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A port of [MUSL]'s libm to Rust.
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[MUSL]: https://www.musl-libc.org/
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2018-07-12 18:43:59 -05:00
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## Goals
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The short term goal of this library is to enable math support (e.g. `sin`, `atan2`) for the
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`wasm32-unknown-unknown` target. The longer term goal is to enable math support in the `core` crate.
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2018-07-12 00:44:28 -05:00
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## Testing
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The test suite of this crate can only be run on x86_64 Linux systems.
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```
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$ # The test suite depends on the `cross` tool so install it if you don't have it
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$ cargo install cross
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$ # and the `cross` tool requires docker to be running
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$ systemctl start docker
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$ # execute the test suite for the x86_64 target
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$ TARGET=x86_64-unknown-linux-gnu bash ci/script.sh
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$ # execute the test suite for the ARMv7 target
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$ TARGET=armv7-unknown-linux-gnueabihf bash ci/script.sh
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```
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## Contributing
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2018-07-12 18:43:59 -05:00
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- Pick your favorite math function from the [issue tracker].
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2018-07-12 00:44:28 -05:00
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- Look for the C implementation of the function in the [MUSL source code][src].
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2018-07-12 19:16:50 -05:00
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- Copy paste the C code into a Rust file in the `src/math` directory and adjust `src/math/mod.rs`
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2018-07-12 20:19:42 -05:00
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accordingly. Also, uncomment the corresponding trait method in `src/lib.rs`.
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2018-07-12 00:44:28 -05:00
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- Run `cargo watch check` and fix the compiler errors.
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2018-07-12 12:43:25 -05:00
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- Tweak the bottom of `test-generator/src/main.rs` to add your function to the test suite.
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2018-07-12 00:44:28 -05:00
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- If you can, run the test suite locally. If you can't, no problem! Your PR will be tested
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automatically.
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- Send us a pull request!
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- :tada:
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2018-07-12 18:43:59 -05:00
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[issue tracker]: https://github.com/japaric/libm/issues
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2018-07-12 12:43:25 -05:00
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[src]: https://git.musl-libc.org/cgit/musl/tree/src/math
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Check [PR #2] for an example.
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[PR #2]: https://github.com/japaric/libm/pull/2
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2018-07-12 00:44:28 -05:00
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### Notes
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2018-07-12 20:19:42 -05:00
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- Only use relative imports within the `math` directory / module, e.g. `use self::fabs::fabs` or
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`use super::isnanf`. Absolute imports from core are OK, e.g. `use core::u64`.
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2018-07-12 00:44:28 -05:00
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- To reinterpret a float as an integer use the `to_bits` method. The MUSL code uses the
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`GET_FLOAT_WORD` macro, or a union, to do this operation.
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- To reinterpret an integer as a float use the `f32::from_bits` constructor. The MUSL code uses the
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`SET_FLOAT_WORD` macro, or a union, to do this operation.
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- Rust code panics on arithmetic overflows when not optimized. You may need to use the [`Wrapping`]
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newtype to avoid this problem.
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[`Wrapping`]: https://doc.rust-lang.org/std/num/struct.Wrapping.html
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## License
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Licensed under either of
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- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
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http://www.apache.org/licenses/LICENSE-2.0)
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- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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at your option.
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### Contribution
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Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the
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work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
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additional terms or conditions.
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