palette_neon_intrinsics.c (4704B)
1 /* palette_neon_intrinsics.c - NEON optimised palette expansion functions 2 * 3 * Copyright (c) 2018-2019 Cosmin Truta 4 * Copyright (c) 2017-2018 Arm Holdings. All rights reserved. 5 * Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017. 6 * 7 * This code is released under the libpng license. 8 * For conditions of distribution and use, see the disclaimer 9 * and license in png.h 10 */ 11 12 #include "../pngpriv.h" 13 14 #if PNG_ARM_NEON_IMPLEMENTATION == 1 15 16 #if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64) 17 # include <arm64_neon.h> 18 #else 19 # include <arm_neon.h> 20 #endif 21 22 /* Build an RGBA8 palette from the separate RGB and alpha palettes. */ 23 void 24 png_riffle_palette_neon(png_structrp png_ptr) 25 { 26 png_const_colorp palette = png_ptr->palette; 27 png_bytep riffled_palette = png_ptr->riffled_palette; 28 png_const_bytep trans_alpha = png_ptr->trans_alpha; 29 int num_trans = png_ptr->num_trans; 30 int i; 31 32 /* Initially black, opaque. */ 33 uint8x16x4_t w = {{ 34 vdupq_n_u8(0x00), 35 vdupq_n_u8(0x00), 36 vdupq_n_u8(0x00), 37 vdupq_n_u8(0xff), 38 }}; 39 40 png_debug(1, "in png_riffle_palette_neon"); 41 42 /* First, riffle the RGB colours into an RGBA8 palette. 43 * The alpha component is set to opaque for now. 44 */ 45 for (i = 0; i < 256; i += 16) 46 { 47 uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i)); 48 w.val[0] = v.val[0]; 49 w.val[1] = v.val[1]; 50 w.val[2] = v.val[2]; 51 vst4q_u8(riffled_palette + (i << 2), w); 52 } 53 54 /* Fix up the missing transparency values. */ 55 for (i = 0; i < num_trans; i++) 56 riffled_palette[(i << 2) + 3] = trans_alpha[i]; 57 } 58 59 /* Expands a palettized row into RGBA8. */ 60 int 61 png_do_expand_palette_rgba8_neon(png_structrp png_ptr, png_row_infop row_info, 62 png_const_bytep row, png_bytepp ssp, png_bytepp ddp) 63 { 64 png_uint_32 row_width = row_info->width; 65 const png_uint_32 *riffled_palette = 66 png_aligncastconst(png_const_uint_32p, png_ptr->riffled_palette); 67 const png_uint_32 pixels_per_chunk = 4; 68 png_uint_32 i; 69 70 png_debug(1, "in png_do_expand_palette_rgba8_neon"); 71 72 PNG_UNUSED(row) 73 if (row_width < pixels_per_chunk) 74 return 0; 75 76 /* This function originally gets the last byte of the output row. 77 * The NEON part writes forward from a given position, so we have 78 * to seek this back by 4 pixels x 4 bytes. 79 */ 80 *ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1); 81 82 for (i = 0; i < row_width; i += pixels_per_chunk) 83 { 84 uint32x4_t cur; 85 png_bytep sp = *ssp - i, dp = *ddp - (i << 2); 86 cur = vld1q_dup_u32 (riffled_palette + *(sp - 3)); 87 cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1); 88 cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2); 89 cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3); 90 vst1q_u32((void *)dp, cur); 91 } 92 if (i != row_width) 93 { 94 /* Remove the amount that wasn't processed. */ 95 i -= pixels_per_chunk; 96 } 97 98 /* Decrement output pointers. */ 99 *ssp = *ssp - i; 100 *ddp = *ddp - (i << 2); 101 return i; 102 } 103 104 /* Expands a palettized row into RGB8. */ 105 int 106 png_do_expand_palette_rgb8_neon(png_structrp png_ptr, png_row_infop row_info, 107 png_const_bytep row, png_bytepp ssp, png_bytepp ddp) 108 { 109 png_uint_32 row_width = row_info->width; 110 png_const_bytep palette = (png_const_bytep)png_ptr->palette; 111 const png_uint_32 pixels_per_chunk = 8; 112 png_uint_32 i; 113 114 png_debug(1, "in png_do_expand_palette_rgb8_neon"); 115 116 PNG_UNUSED(row) 117 if (row_width <= pixels_per_chunk) 118 return 0; 119 120 /* Seeking this back by 8 pixels x 3 bytes. */ 121 *ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1); 122 123 for (i = 0; i < row_width; i += pixels_per_chunk) 124 { 125 uint8x8x3_t cur; 126 png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i); 127 cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7))); 128 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1); 129 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2); 130 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3); 131 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4); 132 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5); 133 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6); 134 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7); 135 vst3_u8((void *)dp, cur); 136 } 137 138 if (i != row_width) 139 { 140 /* Remove the amount that wasn't processed. */ 141 i -= pixels_per_chunk; 142 } 143 144 /* Decrement output pointers. */ 145 *ssp = *ssp - i; 146 *ddp = *ddp - ((i << 1) + i); 147 return i; 148 } 149 150 #endif /* PNG_ARM_NEON_IMPLEMENTATION */