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/* palette_neon_intrinsics.c - NEON optimised palette expansion functions
*
* Copyright (c) 2017 The Chromium Authors. All rights reserved.
* Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#include "../pngpriv.h"
#if PNG_ARM_NEON_IMPLEMENTATION == 1
#include <arm_neon.h>
/* Build an RGBA palette from the RGB and separate alpha palettes. */
void
png_riffle_palette_rgba(png_structrp png_ptr, png_row_infop row_info)
{
png_const_colorp palette = png_ptr->palette;
png_bytep riffled_palette = png_ptr->riffled_palette;
png_const_bytep trans_alpha = png_ptr->trans_alpha;
int num_trans = png_ptr->num_trans;
if (row_info->bit_depth != 8) {
png_error(png_ptr, "bit_depth must be 8 for png_riffle_palette_rgba");
return;
}
/* Initially black, opaque. */
uint8x16x4_t w = {{
vdupq_n_u8(0x00),
vdupq_n_u8(0x00),
vdupq_n_u8(0x00),
vdupq_n_u8(0xff),
}};
int i;
/* First, riffle the RGB colours into a RGBA palette, the A value is
* set to opaque for now. */
for (i = 0; i < (1 << row_info->bit_depth); i += 16) {
uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
w.val[0] = v.val[0];
w.val[1] = v.val[1];
w.val[2] = v.val[2];
vst4q_u8(riffled_palette + (i << 2), w);
}
/* Fix up the missing transparency values. */
for (i = 0; i < num_trans; i++) {
riffled_palette[(i << 2) + 3] = trans_alpha[i];
}
}
/* Expands a palettized row into RGBA. */
int
png_do_expand_palette_neon_rgba(png_structrp png_ptr, png_row_infop row_info,
png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
{
png_uint_32 row_width = row_info->width;
const png_uint_32 *riffled_palette = (const png_uint_32*)png_ptr->riffled_palette;
const png_int_32 pixels_per_chunk = 4;
if (row_width < pixels_per_chunk) {
return 0;
}
/* This function originally gets the last byte of the output row.
The NEON part writes forward from a given position, so we have
to seek this back by 4 pixels x 4 bytes. */
*ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
int i;
for (i = 0; i < row_width; i += pixels_per_chunk) {
uint32x4_t cur;
png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
vst1q_u32((void *)dp, cur);
}
if (i != row_width) {
i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
}
/* Decrement output pointers. */
*ssp = *ssp - i;
*ddp = *ddp - (i << 2);
return i;
}
/* Expands a palettized row into RGB format. */
int
png_do_expand_palette_neon_rgb(png_structrp png_ptr, png_row_infop row_info,
png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
{
png_uint_32 row_width = row_info->width;
png_const_bytep palette = (png_const_bytep)png_ptr->palette;
const png_uint_32 pixels_per_chunk = 8;
if (row_width <= pixels_per_chunk) {
return 0;
}
/* Seeking this back by 8 pixels x 3 bytes. */
*ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
int i;
for (i = 0; i < row_width; i += pixels_per_chunk) {
uint8x8x3_t cur;
png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
vst3_u8((void *)dp, cur);
}
if (i != row_width) {
i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
}
/* Decrement output pointers. */
*ssp = *ssp - i;
*ddp = *ddp - ((i << 1) + i);
return i;
}
#endif /* PNG_ARM_NEON_IMPLEMENTATION */
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