pic-scale 0.7.5

High performance image scaling
Documentation 
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/*
 * Copyright (c) Radzivon Bartoshyk. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1.  Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2.  Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3.  Neither the name of the copyright holder nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
use num_traits::MulAdd;
use std::ops::{Add, Mul};

pub trait ConstSqrt2 {
    fn const_sqrt2() -> Self;
}

impl ConstSqrt2 for f32 {
    #[inline]
    fn const_sqrt2() -> Self {
        std::f32::consts::SQRT_2
    }
}

impl ConstSqrt2 for f64 {
    #[inline]
    fn const_sqrt2() -> Self {
        std::f64::consts::SQRT_2
    }
}

pub trait ConstPI {
    fn const_pi() -> Self;
}

impl ConstPI for f32 {
    #[inline]
    fn const_pi() -> Self {
        std::f32::consts::PI
    }
}

impl ConstPI for f64 {
    #[inline]
    fn const_pi() -> Self {
        std::f64::consts::PI
    }
}

#[cfg(any(
    all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "fma"
    ),
    all(target_arch = "aarch64", feature = "neon")
))]
#[inline(always)]
pub(crate) fn mla<T: Copy + Mul<T, Output = T> + Add<T, Output = T> + MulAdd<T, Output = T>>(
    a: T,
    b: T,
    acc: T,
) -> T {
    MulAdd::mul_add(a, b, acc)
}

#[inline(always)]
#[cfg(not(any(
    all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "fma"
    ),
    all(target_arch = "aarch64", feature = "neon")
)))]
pub(crate) fn mla<T: Copy + Mul<T, Output = T> + Add<T, Output = T> + MulAdd<T, Output = T>>(
    a: T,
    b: T,
    acc: T,
) -> T {
    a * b + acc
}