pic-scale 0.7.8

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 crate::alpha_handle_f16::{premultiply_pixel_f16_row, unpremultiply_pixel_f16_row};
use crate::avx2::utils::{avx_combine_epi, avx_deinterleave_rgba_epi16, avx_interleave_rgba_epi16};
use core::f16;
use std::arch::x86_64::*;

pub(crate) fn avx_premultiply_alpha_rgba_f16(dst: &mut [f16], src: &[f16]) {
    unsafe {
        avx_premultiply_alpha_rgba_f16_row_impl(dst, src);
    }
}

#[target_feature(enable = "avx2", enable = "f16c")]
/// This inlining is required to activate all features for runtime dispatch
fn avx_premultiply_alpha_rgba_f16_row_impl(dst: &mut [f16], src: &[f16]) {
    unsafe {
        let mut rem = dst;
        let mut src_rem = src;

        for (dst, src) in rem
            .chunks_exact_mut(16 * 4)
            .zip(src_rem.chunks_exact(16 * 4))
        {
            let src_ptr = src.as_ptr();
            let lane0 = _mm256_loadu_si256(src_ptr as *const __m256i);
            let lane1 = _mm256_loadu_si256(src_ptr.add(16) as *const __m256i);
            let lane2 = _mm256_loadu_si256(src_ptr.add(32) as *const __m256i);
            let lane3 = _mm256_loadu_si256(src_ptr.add(48) as *const __m256i);
            let pixel = avx_deinterleave_rgba_epi16(lane0, lane1, lane2, lane3);

            let low_alpha = _mm256_cvtph_ps(_mm256_castsi256_si128(pixel.3));
            let low_r = _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.0)), low_alpha);
            let low_g = _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.1)), low_alpha);
            let low_b = _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.2)), low_alpha);

            let high_alpha = _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.3));
            let high_r = _mm256_mul_ps(
                _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.0)),
                high_alpha,
            );
            let high_g = _mm256_mul_ps(
                _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.1)),
                high_alpha,
            );
            let high_b = _mm256_mul_ps(
                _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.2)),
                high_alpha,
            );
            let r_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_r),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_r),
            );
            let g_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_g),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_g),
            );
            let b_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_b),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_b),
            );
            let dst_ptr = dst.as_mut_ptr();
            let (d_lane0, d_lane1, d_lane2, d_lane3) =
                avx_interleave_rgba_epi16(r_values, g_values, b_values, pixel.3);
            _mm256_storeu_si256(dst_ptr as *mut __m256i, d_lane0);
            _mm256_storeu_si256(dst_ptr.add(16) as *mut __m256i, d_lane1);
            _mm256_storeu_si256(dst_ptr.add(32) as *mut __m256i, d_lane2);
            _mm256_storeu_si256(dst_ptr.add(48) as *mut __m256i, d_lane3);
        }

        rem = rem.chunks_exact_mut(16 * 4).into_remainder();
        src_rem = src_rem.chunks_exact(16 * 4).remainder();

        premultiply_pixel_f16_row(rem, src_rem);
    }
}

pub(crate) fn avx_unpremultiply_alpha_rgba_f16(in_place: &mut [f16]) {
    unsafe {
        avx_unpremultiply_alpha_rgba_f16_row_impl(in_place);
    }
}

#[target_feature(enable = "avx2", enable = "f16c")]
/// This inlining is required to activate all features for runtime dispatch
fn avx_unpremultiply_alpha_rgba_f16_row_impl(in_place: &mut [f16]) {
    unsafe {
        let mut rem = in_place;

        for dst in rem.chunks_exact_mut(16 * 4) {
            let src_ptr = dst.as_ptr();
            let lane0 = _mm256_loadu_si256(src_ptr as *const __m256i);
            let lane1 = _mm256_loadu_si256(src_ptr.add(16) as *const __m256i);
            let lane2 = _mm256_loadu_si256(src_ptr.add(32) as *const __m256i);
            let lane3 = _mm256_loadu_si256(src_ptr.add(48) as *const __m256i);
            let pixel = avx_deinterleave_rgba_epi16(lane0, lane1, lane2, lane3);

            let low_alpha = _mm256_cvtph_ps(_mm256_castsi256_si128(pixel.3));
            let zeros = _mm256_setzero_ps();
            let low_alpha_zero_mask = _mm256_cmp_ps::<_CMP_EQ_OS>(low_alpha, zeros);
            let low_r = _mm256_blendv_ps(
                _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.0)), low_alpha),
                zeros,
                low_alpha_zero_mask,
            );
            let low_g = _mm256_blendv_ps(
                _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.1)), low_alpha),
                zeros,
                low_alpha_zero_mask,
            );
            let low_b = _mm256_blendv_ps(
                _mm256_mul_ps(_mm256_cvtph_ps(_mm256_castsi256_si128(pixel.2)), low_alpha),
                zeros,
                low_alpha_zero_mask,
            );

            let high_alpha = _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.3));
            let high_alpha_zero_mask = _mm256_cmp_ps::<_CMP_EQ_OS>(high_alpha, zeros);
            let high_r = _mm256_blendv_ps(
                _mm256_mul_ps(
                    _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.0)),
                    high_alpha,
                ),
                zeros,
                high_alpha_zero_mask,
            );
            let high_g = _mm256_blendv_ps(
                _mm256_mul_ps(
                    _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.1)),
                    high_alpha,
                ),
                zeros,
                high_alpha_zero_mask,
            );
            let high_b = _mm256_blendv_ps(
                _mm256_mul_ps(
                    _mm256_cvtph_ps(_mm256_extracti128_si256::<1>(pixel.2)),
                    high_alpha,
                ),
                zeros,
                high_alpha_zero_mask,
            );
            let r_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_r),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_r),
            );
            let g_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_g),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_g),
            );
            let b_values = avx_combine_epi(
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(low_b),
                _mm256_cvtps_ph::<_MM_FROUND_TO_NEAREST_INT>(high_b),
            );
            let dst_ptr = dst.as_mut_ptr();
            let (d_lane0, d_lane1, d_lane2, d_lane3) =
                avx_interleave_rgba_epi16(r_values, g_values, b_values, pixel.3);
            _mm256_storeu_si256(dst_ptr as *mut __m256i, d_lane0);
            _mm256_storeu_si256(dst_ptr.add(16) as *mut __m256i, d_lane1);
            _mm256_storeu_si256(dst_ptr.add(32) as *mut __m256i, d_lane2);
            _mm256_storeu_si256(dst_ptr.add(48) as *mut __m256i, d_lane3);
        }

        rem = rem.chunks_exact_mut(16 * 4).into_remainder();

        unpremultiply_pixel_f16_row(rem);
    }
}