Fixed-point numbers

The [fixed crate] provides fixed-point numbers. Currently it uses the [typenum crate] for the fractional bit count; it is planned to move to [const generics] when they are implemented by the Rust compiler.

The crate provides the following types:

[FixedI8] is a signed eight-bit fixed-point number,
[FixedI16] is a signed 16-bit fixed-point number,
[FixedI32] is a signed 32-bit fixed-point number,
[FixedI64] is a signed 64-bit fixed-point number,
[FixedI128] is a signed 128-bit fixed-point number,
[FixedU8] is an unsigned eight-bit fixed-point number,
[FixedU16] is an unsigned 16-bit fixed-point number,
[FixedU32] is an unsigned 32-bit fixed-point number,
[FixedU64] is an unsigned 64-bit fixed-point number, and
[FixedU128] is an unsigned 128-bit fixed-point number.

All fixed-point numbers can have Frac fractional bits, where Frac can have any value from 0 up to and including the size of the number in bits. When Frac is 0, the fixed-point number behaves like an integer. When Frac is equal to the number of bits, the value of the fixed-point number lies in the range −0.5 ≤ x < 0.5 for signed fixed-point numbers, and in the range 0 ≤ x < 1 for unsigned fixed-point numbers.

What’s new

Version 0.1.3 news (2018-08-23)

The f16 feature was added, and new methods [from_f16] and [to_f16] were added.

Version 0.1.2 news (2018-08-15)

The crate can now be used without the standard library std.
New methods [from_f32] and [from_f64] were added.
New methods [is_positive] and [is_negative] were added to signed fixed-point numbers.

Version 0.1.1 news (2018-08-11)

Comparisons are now supported between all fixed-point numbers with the same underlying integer type.
New static methods [int_bits] and [frac_bits] were added.
New methods [from_int], [to_int], [to_int_ceil], [to_int_floor] and [to_int_round] were added.
New methods [int] and [frac] were added.
Support for multiplication and division by integers was added.

Other releases

Details on other releases can be found in [RELEASES.md].

Quick example

```rust use fixed::frac; use fixed::FixedI32;

// 20 integer bits, 12 fractional bits type I20F12 = FixedI32; // 19/3 = 6 1/3 let sixandthird = I20F12::fromint(19).unwrap() / 3; // four decimal digits for 12 binary digits asserteq!(sixandthird.tostring(), "6.3333"); // convert to i32, taking the ceil asserteq!(sixandthird.tointceil(), 7); ```

Using the fixed crate

The fixed crate is available on crates.io. To use it in your crate, add it as a dependency inside [Cargo.toml]:

toml [dependencies] fixed = "0.1.3"

You also need to declare it by adding this to your crate root (usually lib.rs or main.rs):

rust extern crate fixed;

The fixed crate requires rustc version 1.28.0 or later.

Optional features

The fixed crate has one optional feature:

f16, disabled by default. This provides conversion to/from [f16]. This features requires the [half crate].

To enable the feature, you can add the dependency like this to [Cargo.toml]:

toml [dependencies.fixed] version = "0.1.3" features = ["f16"]

License

This crate is free software: you can redistribute it and/or modify it under the terms of either

the Apache License, Version 2.0 or
the MIT License

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 License, Version 2.0, shall be dual licensed as above, without any additional terms or conditions.