vendor/packed_simd_2/src/api/cast.rs

   1 //! Implementation of `FromCast` and `IntoCast`.
   2 #![allow(clippy::module_name_repetitions)]
   3
   4 /// Numeric cast from `T` to `Self`.
   5 ///
   6 /// > Note: This is a temporary workaround until the conversion traits
   7 /// specified > in [RFC2484] are implemented.
   8 ///
   9 /// Numeric cast between vectors with the same number of lanes, such that:
  10 ///
  11 /// * casting integer vectors whose lane types have the same size (e.g. `i32xN`
  12 /// -> `u32xN`) is a **no-op**,
  13 ///
  14 /// * casting from a larger integer to a smaller integer (e.g. `u32xN` ->
  15 /// `u8xN`) will **truncate**,
  16 ///
  17 /// * casting from a smaller integer to a larger integer   (e.g. `u8xN` ->
  18 ///   `u32xN`) will:
  19 ///    * **zero-extend** if the source is unsigned, or
  20 ///    * **sign-extend** if the source is signed,
  21 ///
  22 /// * casting from a float to an integer will **round the float towards zero**,
  23 ///
  24 /// * casting from an integer to float will produce the floating point
  25 /// representation of the integer, **rounding to nearest, ties to even**,
  26 ///
  27 /// * casting from an `f32` to an `f64` is perfect and lossless,
  28 ///
  29 /// * casting from an `f64` to an `f32` **rounds to nearest, ties to even**.
  30 ///
  31 /// [RFC2484]: https://github.com/rust-lang/rfcs/pull/2484
  32 pub trait FromCast<T>: crate::marker::Sized {
  33     /// Numeric cast from `T` to `Self`.
  34     fn from_cast(_: T) -> Self;
  35 }
  36
  37 /// Numeric cast from `Self` to `T`.
  38 ///
  39 /// > Note: This is a temporary workaround until the conversion traits
  40 /// specified > in [RFC2484] are implemented.
  41 ///
  42 /// Numeric cast between vectors with the same number of lanes, such that:
  43 ///
  44 /// * casting integer vectors whose lane types have the same size (e.g. `i32xN`
  45 /// -> `u32xN`) is a **no-op**,
  46 ///
  47 /// * casting from a larger integer to a smaller integer (e.g. `u32xN` ->
  48 /// `u8xN`) will **truncate**,
  49 ///
  50 /// * casting from a smaller integer to a larger integer   (e.g. `u8xN` ->
  51 ///   `u32xN`) will:
  52 ///    * **zero-extend** if the source is unsigned, or
  53 ///    * **sign-extend** if the source is signed,
  54 ///
  55 /// * casting from a float to an integer will **round the float towards zero**,
  56 ///
  57 /// * casting from an integer to float will produce the floating point
  58 /// representation of the integer, **rounding to nearest, ties to even**,
  59 ///
  60 /// * casting from an `f32` to an `f64` is perfect and lossless,
  61 ///
  62 /// * casting from an `f64` to an `f32` **rounds to nearest, ties to even**.
  63 ///
  64 /// [RFC2484]: https://github.com/rust-lang/rfcs/pull/2484
  65 pub trait Cast<T>: crate::marker::Sized {
  66     /// Numeric cast from `self` to `T`.
  67     fn cast(self) -> T;
  68 }
  69
  70 /// `FromCast` implies `Cast`.
  71 impl<T, U> Cast<U> for T
  72 where
  73     U: FromCast<T>,
  74 {
  75     #[inline]
  76     fn cast(self) -> U {
  77         U::from_cast(self)
  78     }
  79 }
  80
  81 /// `FromCast` and `Cast` are reflexive
  82 impl<T> FromCast<T> for T {
  83     #[inline]
  84     fn from_cast(t: Self) -> Self {
  85         t
  86     }
  87 }
  88
  89 #[macro_use]
  90 mod macros;
  91
  92 mod v16;
  93 pub use self::v16::*;
  94
  95 mod v32;
  96 pub use self::v32::*;
  97
  98 mod v64;
  99 pub use self::v64::*;
 100
 101 mod v128;
 102 pub use self::v128::*;
 103
 104 mod v256;
 105 pub use self::v256::*;
 106
 107 mod v512;
 108 pub use self::v512::*;