1 files changed, 108 insertions, 0 deletions
diff --git a/third_party/rust/packed_simd/src/api/cast.rs b/third_party/rust/packed_simd/src/api/cast.rs
new file mode 100644
index 0000000000..f1c32ca1a3
--- /dev/null
+++ b/third_party/rust/packed_simd/src/api/cast.rs
@@ -0,0 +1,108 @@
+//! Implementation of `FromCast` and `IntoCast`.
+#![allow(clippy::module_name_repetitions)]
+
+/// Numeric cast from `T` to `Self`.
+///
+/// > Note: This is a temporary workaround until the conversion traits
+/// specified > in [RFC2484] are implemented.
+///
+/// Numeric cast between vectors with the same number of lanes, such that:
+///
+/// * casting integer vectors whose lane types have the same size (e.g. `i32xN`
+/// -> `u32xN`) is a **no-op**,
+///
+/// * casting from a larger integer to a smaller integer (e.g. `u32xN` ->
+/// `u8xN`) will **truncate**,
+///
+/// * casting from a smaller integer to a larger integer   (e.g. `u8xN` ->
+///   `u32xN`) will:
+///    * **zero-extend** if the source is unsigned, or
+///    * **sign-extend** if the source is signed,
+///
+/// * casting from a float to an integer will **round the float towards zero**,
+///
+/// * casting from an integer to float will produce the floating point
+/// representation of the integer, **rounding to nearest, ties to even**,
+///
+/// * casting from an `f32` to an `f64` is perfect and lossless,
+///
+/// * casting from an `f64` to an `f32` **rounds to nearest, ties to even**.
+///
+/// [RFC2484]: https://github.com/rust-lang/rfcs/pull/2484
+pub trait FromCast<T>: crate::marker::Sized {
+    /// Numeric cast from `T` to `Self`.
+    fn from_cast(_: T) -> Self;
+}
+
+/// Numeric cast from `Self` to `T`.
+///
+/// > Note: This is a temporary workaround until the conversion traits
+/// specified > in [RFC2484] are implemented.
+///
+/// Numeric cast between vectors with the same number of lanes, such that:
+///
+/// * casting integer vectors whose lane types have the same size (e.g. `i32xN`
+/// -> `u32xN`) is a **no-op**,
+///
+/// * casting from a larger integer to a smaller integer (e.g. `u32xN` ->
+/// `u8xN`) will **truncate**,
+///
+/// * casting from a smaller integer to a larger integer   (e.g. `u8xN` ->
+///   `u32xN`) will:
+///    * **zero-extend** if the source is unsigned, or
+///    * **sign-extend** if the source is signed,
+///
+/// * casting from a float to an integer will **round the float towards zero**,
+///
+/// * casting from an integer to float will produce the floating point
+/// representation of the integer, **rounding to nearest, ties to even**,
+///
+/// * casting from an `f32` to an `f64` is perfect and lossless,
+///
+/// * casting from an `f64` to an `f32` **rounds to nearest, ties to even**.
+///
+/// [RFC2484]: https://github.com/rust-lang/rfcs/pull/2484
+pub trait Cast<T>: crate::marker::Sized {
+    /// Numeric cast from `self` to `T`.
+    fn cast(self) -> T;
+}
+
+/// `FromCast` implies `Cast`.
+impl<T, U> Cast<U> for T
+where
+    U: FromCast<T>,
+{
+    #[inline]
+    fn cast(self) -> U {
+        U::from_cast(self)
+    }
+}
+
+/// `FromCast` and `Cast` are reflexive
+impl<T> FromCast<T> for T {
+    #[inline]
+    fn from_cast(t: Self) -> Self {
+        t
+    }
+}
+
+#[macro_use]
+mod macros;
+
+mod v16;
+pub use self::v16::*;
+
+mod v32;
+pub use self::v32::*;
+
+mod v64;
+pub use self::v64::*;
+
+mod v128;
+pub use self::v128::*;
+
+mod v256;
+pub use self::v256::*;
+
+mod v512;
+pub use self::v512::*;