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@@ -24,6 +24,20 @@ See [rust-lang/rust#35437][0].
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[2]: https://github.com/rust-lang/compiler-rt/tree/8598065bd965d9713bfafb6c1e766d63a7b17b89/lib/builtins
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[3]: https://travis-ci.org/japaric/rustc-builtins
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+### Porting Reminders
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+
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+1. [Rust][4] and [C][5] have slightly different operator precedence. C evaluates comparisons (`== !=`) before bitwise operations (`& | ^`), while Rust evaluates the other way.
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+2. C assumes wrapping operations everywhere. Rust panics on overflow when in debug mode. Consider using the [Wrapping][6] type or the explicit [wrapping_*][7] functions where applicable.
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+3. Note [C implicit casts][8], especially integer promotion. Rust is much more explicit about casting, so be sure that any cast which affects the output is ported to the Rust implementation.
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+4. Rust has [many functions][9] for integer or floating point manipulation in the standard library. Consider using one of these functions rather than porting a new one.
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+
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+[4]: https://doc.rust-lang.org/reference.html#operator-precedence
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+[5]: http://en.cppreference.com/w/c/language/operator_precedence
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+[6]: https://doc.rust-lang.org/core/num/struct.Wrapping.html
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+[7]: https://doc.rust-lang.org/std/primitive.i32.html#method.wrapping_add
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+[8]: http://en.cppreference.com/w/cpp/language/implicit_conversion
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+[9]: https://doc.rust-lang.org/std/primitive.i32.html
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+
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## Progress
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- [x] adddf3.c
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Matt Ickstadt