hpvca 0.1.11

HEVC/HEIC tiny image encoder
Documentation 
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/*
 * // Copyright (c) Radzivon Bartoshyk 6/2026. 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.
 */

#[cfg(any(
    all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "fma"
    ),
    target_arch = "aarch64"
))]
#[inline(always)]
#[allow(unused)]
pub(crate) fn fmla(a: f32, b: f32, c: f32) -> f32 {
    f32::mul_add(a, b, c)
}

#[cfg(not(any(
    all(
        any(target_arch = "x86", target_arch = "x86_64"),
        target_feature = "fma"
    ),
    target_arch = "aarch64"
)))]
#[inline(always)]
#[allow(unused)]
pub(crate) fn fmla(a: f32, b: f32, c: f32) -> f32 {
    a * b + c
}

pub(crate) trait FastRound {
    fn fast_round(self) -> Self;
}

impl FastRound for f32 {
    #[inline(always)]
    fn fast_round(self) -> Self {
        #[cfg(all(
            any(target_arch = "x86", target_arch = "x86_64"),
            target_feature = "sse4.1"
        ))]
        {
            const MAGIC: f32 = ((1u32 << 23) + (1u32 << 22)) as f32;
            (f32::from_bits(self.to_bits() + 1) + MAGIC) - MAGIC
        }
        #[cfg(target_arch = "aarch64")]
        {
            self.round()
        }
        #[cfg(not(any(
            target_arch = "aarch64",
            all(
                any(target_arch = "x86", target_arch = "x86_64"),
                target_feature = "sse4.1"
            )
        )))]
        {
            const MAGIC: f32 = ((1u32 << 23) + (1u32 << 22)) as f32;
            (f32::from_bits(self.to_bits() + 1) + MAGIC) - MAGIC
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn fast_round_matches_round_for_aq_values() {
        for value in -4096..=4096 {
            let value = value as f32 / 256.0;
            assert_eq!(value.fast_round(), value.round(), "value={value}");
        }
    }
}