libblur 0.24.0

Fast image blurring in pure Rust
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::EdgeMode;
use crate::edge_mode::clamp_edge;
use crate::unsafe_slice::UnsafeSlice;
use crate::wasm32::utils::{
    load_u8_s32_fast, u16x8_pack_trunc_u8x16, u32x4_pack_trunc_u16x8, w_store_u8x8_m4,
};
use std::arch::wasm32::*;

pub(crate) fn fg_horizontal_pass_wasm_u8<const CN: usize>(
    bytes: &UnsafeSlice<u8>,
    stride: u32,
    width: u32,
    height: u32,
    radius: u32,
    start: u32,
    end: u32,
    edge_mode: EdgeMode,
) {
    fast_gaussian_horizontal_pass_impl::<CN>(
        bytes, stride, width, height, radius, start, end, edge_mode,
    );
}

#[inline]
#[target_feature(enable = "simd128")]
fn fast_gaussian_horizontal_pass_impl<const CN: usize>(
    bytes: &UnsafeSlice<u8>,
    stride: u32,
    width: u32,
    height: u32,
    radius: u32,
    start: u32,
    end: u32,
    edge_mode: EdgeMode,
) {
    unsafe {
        let mut buffer: [[i32; 4]; 1024] = [[0; 4]; 1024];
        let initial_sum = ((radius * radius) >> 1) as i32;

        let radius_64 = radius as i64;
        let width_wide = width as i64;
        let v_weight = f32x4_splat((1f64 / (radius as f64 * radius as f64)) as f32);
        for y in start..std::cmp::min(height, end) {
            let mut diffs = i32x4_splat(0);
            let mut summs = i32x4_splat(initial_sum);

            let current_y = ((y as i64) * (stride as i64)) as usize;

            let start_x = 0 - 2 * radius_64;
            for x in start_x..(width as i64) {
                if x >= 0 {
                    let current_px = ((x.max(0) as u32) * CN as u32) as usize;

                    let prepared_px_s32 = i32x4_trunc_sat_f32x4(f32x4_nearest(f32x4_mul(
                        f32x4_convert_i32x4(summs),
                        v_weight,
                    )));
                    let prepared_u16 = u32x4_pack_trunc_u16x8(prepared_px_s32, prepared_px_s32);
                    let prepared_u8 = u16x8_pack_trunc_u8x16(prepared_u16, prepared_u16);

                    let bytes_offset = current_y + current_px;
                    let dst_ptr = bytes.get_ptr(bytes_offset);
                    w_store_u8x8_m4::<CN>(dst_ptr, prepared_u8);

                    let arr_index = ((x - radius_64) & 1023) as usize;
                    let d_arr_index = (x & 1023) as usize;

                    let d_buf_ptr = buffer.get_unchecked(d_arr_index);
                    let mut d_stored = v128_load(d_buf_ptr.as_ptr().cast());
                    d_stored = i32x4_shr(d_stored, 1);

                    let buf_ptr = buffer.get_unchecked(arr_index);
                    let a_stored = v128_load(buf_ptr.as_ptr().cast());

                    diffs = i32x4_add(diffs, i32x4_sub(a_stored, d_stored));
                } else if x + radius_64 >= 0 {
                    let arr_index = (x & 1023) as usize;
                    let buf_ptr = buffer.get_unchecked(arr_index);
                    let mut stored = v128_load(buf_ptr.as_ptr().cast());
                    stored = i32x4_shr(stored, 1);
                    diffs = i32x4_sub(diffs, stored);
                }

                let next_row_y = (y as usize) * (stride as usize);
                let next_row_x = clamp_edge!(edge_mode, x + radius_64, 0, width_wide);
                let next_row_px = next_row_x * CN;

                let s_ptr = bytes.get_ptr(next_row_y + next_row_px);
                let pixel_color = load_u8_s32_fast::<CN>(s_ptr);

                let arr_index = ((x + radius_64) & 1023) as usize;
                let buf_ptr = buffer.get_unchecked_mut(arr_index).as_mut_ptr();

                diffs = i32x4_add(diffs, pixel_color);
                summs = i32x4_add(summs, diffs);
                v128_store(buf_ptr.cast(), pixel_color);
            }
        }
    }
}

pub(crate) fn fg_vertical_pass_wasm_u8<const CN: usize>(
    bytes: &UnsafeSlice<u8>,
    stride: u32,
    width: u32,
    height: u32,
    radius: u32,
    start: u32,
    end: u32,
    edge_mode: EdgeMode,
) {
    fast_gaussian_vertical_pass_wasm::<CN>(
        bytes, stride, width, height, radius, start, end, edge_mode,
    );
}

#[inline]
#[target_feature(enable = "simd128")]
fn fast_gaussian_vertical_pass_wasm<const CN: usize>(
    bytes: &UnsafeSlice<u8>,
    stride: u32,
    width: u32,
    height: u32,
    radius: u32,
    start: u32,
    end: u32,
    edge_mode: EdgeMode,
) {
    unsafe {
        let mut buffer: [[i32; 4]; 1024] = [[0; 4]; 1024];
        let initial_sum = ((radius * radius) >> 1) as i32;

        let height_wide = height as i64;

        let radius_64 = radius as i64;
        let v_weight = f32x4_splat((1f64 / (radius as f64 * radius as f64)) as f32);
        for x in start..std::cmp::min(width, end) {
            let mut diffs = i32x4_splat(0);
            let mut summs = i32x4_splat(initial_sum);

            let start_y = 0 - 2 * radius as i64;
            for y in start_y..height_wide {
                let current_y = (y * (stride as i64)) as usize;

                if y >= 0 {
                    let current_px = (x * CN as u32) as usize;

                    let prepared_px_s32 = i32x4_trunc_sat_f32x4(f32x4_nearest(f32x4_mul(
                        f32x4_convert_i32x4(summs),
                        v_weight,
                    )));
                    let prepared_u16 = u32x4_pack_trunc_u16x8(prepared_px_s32, prepared_px_s32);
                    let prepared_u8 = u16x8_pack_trunc_u8x16(prepared_u16, prepared_u16);

                    let bytes_offset = current_y + current_px;

                    w_store_u8x8_m4::<CN>(bytes.get_ptr(bytes_offset), prepared_u8);

                    let arr_index = ((y - radius_64) & 1023) as usize;
                    let d_arr_index = (y & 1023) as usize;

                    let d_buf_ptr = buffer.get_unchecked(d_arr_index);
                    let mut d_stored = v128_load(d_buf_ptr.as_ptr().cast());
                    d_stored = i32x4_shr(d_stored, 1);

                    let buf_ptr = buffer.get_unchecked(arr_index);
                    let a_stored = v128_load(buf_ptr.as_ptr().cast());

                    diffs = i32x4_add(diffs, i32x4_sub(a_stored, d_stored));
                } else if y + radius_64 >= 0 {
                    let arr_index = (y & 1023) as usize;
                    let buf_ptr = buffer.get_unchecked(arr_index);
                    let mut stored = v128_load(buf_ptr.as_ptr().cast());
                    stored = i32x4_shr(stored, 1);
                    diffs = i32x4_sub(diffs, stored);
                }

                let next_row_y =
                    clamp_edge!(edge_mode, y + radius_64, 0, height_wide) * (stride as usize);
                let next_row_x = (x * CN as u32) as usize;

                let s_ptr = bytes.get_ptr(next_row_y + next_row_x);
                let pixel_color = load_u8_s32_fast::<CN>(s_ptr);

                let arr_index = ((y + radius_64) & 1023) as usize;
                let buf_ptr = buffer.get_unchecked_mut(arr_index).as_mut_ptr();

                diffs = i32x4_add(diffs, pixel_color);
                summs = i32x4_add(summs, diffs);
                v128_store(buf_ptr.cast(), pixel_color);
            }
        }
    }
}