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//! Contains utility functions and traits to convert between vectors of `u16` bits and `f16` or //! `bf16` vectors. //! //! The utility [`HalfBitsVecExt`] sealed extension trait is implemented for `Vec<u16>` vectors, //! while the utility [`HalfFloatVecExt`] sealed extension trait is implemented for both `Vec<f16>` //! and `Vec<bf16>` vectors. These traits provide efficient conversions and reinterpret casting of //! larger buffers of floating point values, and are automatically included in the [`prelude`] //! module. //! //! This module is only available with the `std` feature. //! //! [`HalfBitsVecExt`]: trait.HalfBitsVecExt.html //! [`HalfFloatVecExt`]: trait.HalfFloatVecExt.html //! [`prelude`]: ../prelude/index.html #![cfg(feature = "std")] use super::{bf16, f16, slice::HalfFloatSliceExt}; use core::mem; /// Extensions to `Vec<f16>` and `Vec<bf16>` to support reinterpret operations. /// /// This trait is sealed and cannot be implemented outside of this crate. pub trait HalfFloatVecExt: private::SealedHalfFloatVec { /// Reinterpret a vector of [`f16`](../struct.f16.html) or [`bf16`](../struct.bf16.html) /// numbers as a vector of `u16` bits. /// /// This is a zero-copy operation. The reinterpreted vector has the same memory location as /// `self`. /// /// # Examples /// /// ```rust /// # use half::prelude::*; /// let float_buffer = vec![f16::from_f32(1.), f16::from_f32(2.), f16::from_f32(3.)]; /// let int_buffer = float_buffer.reinterpret_into(); /// /// assert_eq!(int_buffer, [f16::from_f32(1.).to_bits(), f16::from_f32(2.).to_bits(), f16::from_f32(3.).to_bits()]); /// ``` fn reinterpret_into(self) -> Vec<u16>; /// Convert all of the elements of a `[f32]` slice into a new [`f16`](../struct.f16.html) or /// [`bf16`](../struct.bf16.html) vector. /// /// The conversion operation is vectorized over the slice, meaning the conversion may be more /// efficient than converting individual elements on some hardware that supports SIMD /// conversions. See [crate documentation](../index.html) for more information on hardware /// conversion support. /// /// # Examples /// ```rust /// # use half::prelude::*; /// let float_values = [1., 2., 3., 4.]; /// let vec: Vec<f16> = Vec::from_f32_slice(&float_values); /// /// assert_eq!(vec, vec![f16::from_f32(1.), f16::from_f32(2.), f16::from_f32(3.), f16::from_f32(4.)]); /// ``` fn from_f32_slice(slice: &[f32]) -> Self; /// Convert all of the elements of a `[f64]` slice into a new [`f16`](../struct.f16.html) or /// [`bf16`](../struct.bf16.html) vector. /// /// The conversion operation is vectorized over the slice, meaning the conversion may be more /// efficient than converting individual elements on some hardware that supports SIMD /// conversions. See [crate documentation](../index.html) for more information on hardware /// conversion support. /// /// # Examples /// ```rust /// # use half::prelude::*; /// let float_values = [1., 2., 3., 4.]; /// let vec: Vec<f16> = Vec::from_f64_slice(&float_values); /// /// assert_eq!(vec, vec![f16::from_f64(1.), f16::from_f64(2.), f16::from_f64(3.), f16::from_f64(4.)]); /// ``` fn from_f64_slice(slice: &[f64]) -> Self; } /// Extensions to `Vec<u16>` to support reinterpret operations. /// /// This trait is sealed and cannot be implemented outside of this crate. pub trait HalfBitsVecExt: private::SealedHalfBitsVec { /// Reinterpret a vector of `u16` bits as a vector of [`f16`](../struct.f16.html) or /// [`bf16`](../struct.bf16.html) numbers. /// /// `H` is the type to cast to, and must be either the [`f16`](../struct.f16.html) or /// [`bf16`](../struct.bf16.html) type. /// /// This is a zero-copy operation. The reinterpreted vector has the same memory location as /// `self`. /// /// # Examples /// /// ```rust /// # use half::prelude::*; /// let int_buffer = vec![f16::from_f32(1.).to_bits(), f16::from_f32(2.).to_bits(), f16::from_f32(3.).to_bits()]; /// let float_buffer = int_buffer.reinterpret_into::<f16>(); /// /// assert_eq!(float_buffer, [f16::from_f32(1.), f16::from_f32(2.), f16::from_f32(3.)]); /// ``` fn reinterpret_into<H>(self) -> Vec<H> where H: crate::private::SealedHalf; } mod private { use crate::{bf16, f16}; pub trait SealedHalfFloatVec {} impl SealedHalfFloatVec for Vec<f16> {} impl SealedHalfFloatVec for Vec<bf16> {} pub trait SealedHalfBitsVec {} impl SealedHalfBitsVec for Vec<u16> {} } impl HalfFloatVecExt for Vec<f16> { #[inline] fn reinterpret_into(mut self) -> Vec<u16> { // An f16 array has same length and capacity as u16 array let length = self.len(); let capacity = self.capacity(); // Actually reinterpret the contents of the Vec<f16> as u16, // knowing that structs are represented as only their members in memory, // which is the u16 part of `f16(u16)` let pointer = self.as_mut_ptr() as *mut u16; // Prevent running a destructor on the old Vec<u16>, so the pointer won't be deleted mem::forget(self); // Finally construct a new Vec<f16> from the raw pointer // SAFETY: We are reconstructing full length and capacity of original vector, // using its original pointer, and the size of elements are identical. unsafe { Vec::from_raw_parts(pointer, length, capacity) } } fn from_f32_slice(slice: &[f32]) -> Self { let mut vec = Vec::with_capacity(slice.len()); // SAFETY: convert will initialize every value in the vector without reading them, // so this is safe to do instead of double initialize from resize, and we're setting it to // same value as capacity. unsafe { vec.set_len(slice.len()) }; vec.convert_from_f32_slice(&slice); vec } fn from_f64_slice(slice: &[f64]) -> Self { let mut vec = Vec::with_capacity(slice.len()); // SAFETY: convert will initialize every value in the vector without reading them, // so this is safe to do instead of double initialize from resize, and we're setting it to // same value as capacity. unsafe { vec.set_len(slice.len()) }; vec.convert_from_f64_slice(&slice); vec } } impl HalfFloatVecExt for Vec<bf16> { #[inline] fn reinterpret_into(mut self) -> Vec<u16> { // An f16 array has same length and capacity as u16 array let length = self.len(); let capacity = self.capacity(); // Actually reinterpret the contents of the Vec<f16> as u16, // knowing that structs are represented as only their members in memory, // which is the u16 part of `f16(u16)` let pointer = self.as_mut_ptr() as *mut u16; // Prevent running a destructor on the old Vec<u16>, so the pointer won't be deleted mem::forget(self); // Finally construct a new Vec<f16> from the raw pointer // SAFETY: We are reconstructing full length and capacity of original vector, // using its original pointer, and the size of elements are identical. unsafe { Vec::from_raw_parts(pointer, length, capacity) } } fn from_f32_slice(slice: &[f32]) -> Self { let mut vec = Vec::with_capacity(slice.len()); // SAFETY: convert will initialize every value in the vector without reading them, // so this is safe to do instead of double initialize from resize, and we're setting it to // same value as capacity. unsafe { vec.set_len(slice.len()) }; vec.convert_from_f32_slice(&slice); vec } fn from_f64_slice(slice: &[f64]) -> Self { let mut vec = Vec::with_capacity(slice.len()); // SAFETY: convert will initialize every value in the vector without reading them, // so this is safe to do instead of double initialize from resize, and we're setting it to // same value as capacity. unsafe { vec.set_len(slice.len()) }; vec.convert_from_f64_slice(&slice); vec } } impl HalfBitsVecExt for Vec<u16> { // This is safe because all traits are sealed #[inline] fn reinterpret_into<H>(mut self) -> Vec<H> where H: crate::private::SealedHalf, { // An f16 array has same length and capacity as u16 array let length = self.len(); let capacity = self.capacity(); // Actually reinterpret the contents of the Vec<u16> as f16, // knowing that structs are represented as only their members in memory, // which is the u16 part of `f16(u16)` let pointer = self.as_mut_ptr() as *mut H; // Prevent running a destructor on the old Vec<u16>, so the pointer won't be deleted mem::forget(self); // Finally construct a new Vec<f16> from the raw pointer // SAFETY: We are reconstructing full length and capacity of original vector, // using its original pointer, and the size of elements are identical. unsafe { Vec::from_raw_parts(pointer, length, capacity) } } } /// Converts a vector of `u16` elements into a vector of [`f16`](../struct.f16.html) elements. /// /// This function merely reinterprets the contents of the vector, so it's a zero-copy operation. #[deprecated( since = "1.4.0", note = "use [`HalfBitsVecExt::reinterpret_into`](trait.HalfBitsVecExt.html#tymethod.reinterpret_into) instead" )] #[inline] pub fn from_bits(bits: Vec<u16>) -> Vec<f16> { bits.reinterpret_into() } /// Converts a vector of [`f16`](../struct.f16.html) elements into a vector of `u16` elements. /// /// This function merely reinterprets the contents of the vector, so it's a zero-copy operation. #[deprecated( since = "1.4.0", note = "use [`HalfFloatVecExt::reinterpret_into`](trait.HalfFloatVecExt.html#tymethod.reinterpret_into) instead" )] #[inline] pub fn to_bits(numbers: Vec<f16>) -> Vec<u16> { numbers.reinterpret_into() } #[cfg(test)] mod test { use super::{HalfBitsVecExt, HalfFloatVecExt}; use crate::{bf16, f16}; #[test] fn test_vec_conversions_f16() { let numbers = vec![f16::E, f16::PI, f16::EPSILON, f16::FRAC_1_SQRT_2]; let bits = vec![ f16::E.to_bits(), f16::PI.to_bits(), f16::EPSILON.to_bits(), f16::FRAC_1_SQRT_2.to_bits(), ]; let bits_cloned = bits.clone(); // Convert from bits to numbers let from_bits = bits.reinterpret_into::<f16>(); assert_eq!(&from_bits[..], &numbers[..]); // Convert from numbers back to bits let to_bits = from_bits.reinterpret_into(); assert_eq!(&to_bits[..], &bits_cloned[..]); } #[test] fn test_vec_conversions_bf16() { let numbers = vec![bf16::E, bf16::PI, bf16::EPSILON, bf16::FRAC_1_SQRT_2]; let bits = vec![ bf16::E.to_bits(), bf16::PI.to_bits(), bf16::EPSILON.to_bits(), bf16::FRAC_1_SQRT_2.to_bits(), ]; let bits_cloned = bits.clone(); // Convert from bits to numbers let from_bits = bits.reinterpret_into::<bf16>(); assert_eq!(&from_bits[..], &numbers[..]); // Convert from numbers back to bits let to_bits = from_bits.reinterpret_into(); assert_eq!(&to_bits[..], &bits_cloned[..]); } }