From 7734cda20cf1236aef60f3bbd2267c97bbb40869 Mon Sep 17 00:00:00 2001 From: Richard Townsend Date: Thu, 25 Jan 2018 19:03:04 +0000 Subject: [PATCH] Optimize png_do_expand_palette for ARM ARM-specific optimization processes 8 or 4 pixels at once. Improves performance by around 10-22% on a recent ARM Chromebook. --- CMakeLists.txt | 3 +- Makefile.am | 3 +- arm/palette_neon_intrinsics.c | 137 ++++++++++++++++++++++++++++++++++ pngpriv.h | 23 ++++++ pngrtran.c | 49 ++++++++++-- pngstruct.h | 4 + pngwrite.c | 4 + 7 files changed, 213 insertions(+), 10 deletions(-) create mode 100644 arm/palette_neon_intrinsics.c diff --git a/CMakeLists.txt b/CMakeLists.txt index 34b776338..a49127d06 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -105,7 +105,8 @@ if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR set(libpng_arm_sources arm/arm_init.c arm/filter_neon.S - arm/filter_neon_intrinsics.c) + arm/filter_neon_intrinsics.c + arm/palette_neon_intrinsics.c) if(${PNG_ARM_NEON} STREQUAL "on") add_definitions(-DPNG_ARM_NEON_OPT=2) diff --git a/Makefile.am b/Makefile.am index 08db3e599..e4d08b5e1 100644 --- a/Makefile.am +++ b/Makefile.am @@ -95,7 +95,8 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\ if PNG_ARM_NEON libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\ - arm/filter_neon.S arm/filter_neon_intrinsics.c + arm/filter_neon.S arm/filter_neon_intrinsics.c \ + arm/palette_neon_intrinsics.c endif if PNG_MIPS_MSA diff --git a/arm/palette_neon_intrinsics.c b/arm/palette_neon_intrinsics.c new file mode 100644 index 000000000..90fc2e490 --- /dev/null +++ b/arm/palette_neon_intrinsics.c @@ -0,0 +1,137 @@ +/* palette_neon_intrinsics.c - NEON optimised palette expansion functions + * + * Copyright (c) 2017-2018 Arm Holdings. All rights reserved. + * Written by Richard Townsend , 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 + +/* 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 */ diff --git a/pngpriv.h b/pngpriv.h index a23febb81..973c3eac1 100644 --- a/pngpriv.h +++ b/pngpriv.h @@ -2117,6 +2117,29 @@ PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2, PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr, png_const_charp key, png_bytep new_key), PNG_EMPTY); +#if PNG_ARM_NEON_IMPLEMENTATION == 1 +PNG_INTERNAL_FUNCTION(void, + png_riffle_palette_rgba, + (png_structrp, png_row_infop), + PNG_EMPTY); +PNG_INTERNAL_FUNCTION(int, + png_do_expand_palette_neon_rgba, + (png_structrp, + png_row_infop, + png_const_bytep, + const png_bytepp, + const png_bytepp), + PNG_EMPTY); +PNG_INTERNAL_FUNCTION(int, + png_do_expand_palette_neon_rgb, + (png_structrp, + png_row_infop, + png_const_bytep, + const png_bytepp, + const png_bytepp), + PNG_EMPTY); +#endif + /* Maintainer: Put new private prototypes here ^ */ #include "pngdebug.h" diff --git a/pngrtran.c b/pngrtran.c index 6b9b7202f..292843d4f 100644 --- a/pngrtran.c +++ b/pngrtran.c @@ -18,6 +18,13 @@ #include "pngpriv.h" +#ifdef PNG_ARM_NEON_IMPLEMENTATION +#if PNG_ARM_NEON_IMPLEMENTATION == 1 +#define PNG_ARM_NEON_INTRINSICS_AVAILABLE +#include +#endif +#endif + #ifdef PNG_READ_SUPPORTED /* Set the action on getting a CRC error for an ancillary or critical chunk. */ @@ -4195,8 +4202,9 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr) * upon whether you supply trans and num_trans. */ static void -png_do_expand_palette(png_row_infop row_info, png_bytep row, - png_const_colorp palette, png_const_bytep trans_alpha, int num_trans) +png_do_expand_palette(png_structrp png_ptr, png_row_infop row_info, + png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha, + int num_trans) { int shift, value; png_bytep sp, dp; @@ -4300,14 +4308,22 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row, sp = row + (size_t)row_width - 1; dp = row + ((size_t)row_width << 2) - 1; - for (i = 0; i < row_width; i++) + i = 0; +#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE + if (png_ptr->riffled_palette != NULL) { + /* The RGBA optimization works with png_ptr->bit_depth == 8 + but sometimes row_info->bit_depth has been changed to 8. + In these cases, the palette hasn't been riffled. */ + i = png_do_expand_palette_neon_rgba(png_ptr, row_info, row, &sp, &dp); + } +#endif + + for (; i < row_width; i++) { if ((int)(*sp) >= num_trans) *dp-- = 0xff; - else *dp-- = trans_alpha[*sp]; - *dp-- = palette[*sp].blue; *dp-- = palette[*sp].green; *dp-- = palette[*sp].red; @@ -4324,8 +4340,12 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row, { sp = row + (size_t)row_width - 1; dp = row + (size_t)(row_width * 3) - 1; + i = 0; +#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE + i = png_do_expand_palette_neon_rgb(png_ptr, row_info, row, &sp, &dp); +#endif - for (i = 0; i < row_width; i++) + for (; i < row_width; i++) { *dp-- = palette[*sp].blue; *dp-- = palette[*sp].green; @@ -4739,8 +4759,21 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info) { if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) { - png_do_expand_palette(row_info, png_ptr->row_buf + 1, - png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans); +#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE + if ((png_ptr->num_trans > 0) && (png_ptr->bit_depth == 8)) { + /* Allocate space for the decompressed full palette. */ + if (png_ptr->riffled_palette == NULL) { + png_ptr->riffled_palette = png_malloc(png_ptr, 256*4); + if (png_ptr->riffled_palette == NULL) { + png_error(png_ptr, "NULL row buffer"); + } + /* Build the RGBA palette. */ + png_riffle_palette_rgba(png_ptr, row_info); + } + } +#endif + png_do_expand_palette(png_ptr, row_info, png_ptr->row_buf + 1, + png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans); } else diff --git a/pngstruct.h b/pngstruct.h index d57603177..94a6d041f 100644 --- a/pngstruct.h +++ b/pngstruct.h @@ -228,6 +228,10 @@ struct png_struct_def * big_row_buf; while writing it is separately * allocated. */ +#ifdef PNG_READ_EXPAND_SUPPORTED + /* Buffer to accelerate palette transformations. */ + png_bytep riffled_palette; +#endif #ifdef PNG_WRITE_FILTER_SUPPORTED png_bytep try_row; /* buffer to save trial row when filtering */ png_bytep tst_row; /* buffer to save best trial row when filtering */ diff --git a/pngwrite.c b/pngwrite.c index 98bce0e35..160c877d3 100644 --- a/pngwrite.c +++ b/pngwrite.c @@ -948,6 +948,10 @@ png_write_destroy(png_structrp png_ptr) png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list); png_free(png_ptr, png_ptr->row_buf); png_ptr->row_buf = NULL; +#ifdef PNG_READ_EXPANDED_SUPPORTED + png_free(png_ptr, png_ptr->riffled_palette); + png_ptr->riffled_palette = NULL; +#endif #ifdef PNG_WRITE_FILTER_SUPPORTED png_free(png_ptr, png_ptr->prev_row); png_free(png_ptr, png_ptr->try_row);