alpha_processing_neon.c (7261B)
1 // Copyright 2017 Google Inc. All Rights Reserved. 2 // 3 // Use of this source code is governed by a BSD-style license 4 // that can be found in the COPYING file in the root of the source 5 // tree. An additional intellectual property rights grant can be found 6 // in the file PATENTS. All contributing project authors may 7 // be found in the AUTHORS file in the root of the source tree. 8 // ----------------------------------------------------------------------------- 9 // 10 // Utilities for processing transparent channel, NEON version. 11 // 12 // Author: Skal (pascal.massimino@gmail.com) 13 14 #include "src/dsp/dsp.h" 15 16 #if defined(WEBP_USE_NEON) 17 18 #include "src/dsp/neon.h" 19 20 //------------------------------------------------------------------------------ 21 22 #define MULTIPLIER(a) ((a) * 0x8081) 23 #define PREMULTIPLY(x, m) (((x) * (m)) >> 23) 24 25 #define MULTIPLY_BY_ALPHA(V, ALPHA, OTHER) do { \ 26 const uint8x8_t alpha = (V).val[(ALPHA)]; \ 27 const uint16x8_t r1 = vmull_u8((V).val[1], alpha); \ 28 const uint16x8_t g1 = vmull_u8((V).val[2], alpha); \ 29 const uint16x8_t b1 = vmull_u8((V).val[(OTHER)], alpha); \ 30 /* we use: v / 255 = (v + 1 + (v >> 8)) >> 8 */ \ 31 const uint16x8_t r2 = vsraq_n_u16(r1, r1, 8); \ 32 const uint16x8_t g2 = vsraq_n_u16(g1, g1, 8); \ 33 const uint16x8_t b2 = vsraq_n_u16(b1, b1, 8); \ 34 const uint16x8_t r3 = vaddq_u16(r2, kOne); \ 35 const uint16x8_t g3 = vaddq_u16(g2, kOne); \ 36 const uint16x8_t b3 = vaddq_u16(b2, kOne); \ 37 (V).val[1] = vshrn_n_u16(r3, 8); \ 38 (V).val[2] = vshrn_n_u16(g3, 8); \ 39 (V).val[(OTHER)] = vshrn_n_u16(b3, 8); \ 40 } while (0) 41 42 static void ApplyAlphaMultiply_NEON(uint8_t* rgba, int alpha_first, 43 int w, int h, int stride) { 44 const uint16x8_t kOne = vdupq_n_u16(1u); 45 while (h-- > 0) { 46 uint32_t* const rgbx = (uint32_t*)rgba; 47 int i = 0; 48 if (alpha_first) { 49 for (; i + 8 <= w; i += 8) { 50 // load aaaa...|rrrr...|gggg...|bbbb... 51 uint8x8x4_t RGBX = vld4_u8((const uint8_t*)(rgbx + i)); 52 MULTIPLY_BY_ALPHA(RGBX, 0, 3); 53 vst4_u8((uint8_t*)(rgbx + i), RGBX); 54 } 55 } else { 56 for (; i + 8 <= w; i += 8) { 57 uint8x8x4_t RGBX = vld4_u8((const uint8_t*)(rgbx + i)); 58 MULTIPLY_BY_ALPHA(RGBX, 3, 0); 59 vst4_u8((uint8_t*)(rgbx + i), RGBX); 60 } 61 } 62 // Finish with left-overs. 63 for (; i < w; ++i) { 64 uint8_t* const rgb = rgba + (alpha_first ? 1 : 0); 65 const uint8_t* const alpha = rgba + (alpha_first ? 0 : 3); 66 const uint32_t a = alpha[4 * i]; 67 if (a != 0xff) { 68 const uint32_t mult = MULTIPLIER(a); 69 rgb[4 * i + 0] = PREMULTIPLY(rgb[4 * i + 0], mult); 70 rgb[4 * i + 1] = PREMULTIPLY(rgb[4 * i + 1], mult); 71 rgb[4 * i + 2] = PREMULTIPLY(rgb[4 * i + 2], mult); 72 } 73 } 74 rgba += stride; 75 } 76 } 77 #undef MULTIPLY_BY_ALPHA 78 #undef MULTIPLIER 79 #undef PREMULTIPLY 80 81 //------------------------------------------------------------------------------ 82 83 static int DispatchAlpha_NEON(const uint8_t* WEBP_RESTRICT alpha, 84 int alpha_stride, int width, int height, 85 uint8_t* WEBP_RESTRICT dst, int dst_stride) { 86 uint32_t alpha_mask = 0xffu; 87 uint8x8_t mask8 = vdup_n_u8(0xff); 88 uint32_t tmp[2]; 89 int i, j; 90 for (j = 0; j < height; ++j) { 91 // We don't know if alpha is first or last in dst[] (depending on rgbA/Argb 92 // mode). So we must be sure dst[4*i + 8 - 1] is writable for the store. 93 // Hence the test with 'width - 1' instead of just 'width'. 94 for (i = 0; i + 8 <= width - 1; i += 8) { 95 uint8x8x4_t rgbX = vld4_u8((const uint8_t*)(dst + 4 * i)); 96 const uint8x8_t alphas = vld1_u8(alpha + i); 97 rgbX.val[0] = alphas; 98 vst4_u8((uint8_t*)(dst + 4 * i), rgbX); 99 mask8 = vand_u8(mask8, alphas); 100 } 101 for (; i < width; ++i) { 102 const uint32_t alpha_value = alpha[i]; 103 dst[4 * i] = alpha_value; 104 alpha_mask &= alpha_value; 105 } 106 alpha += alpha_stride; 107 dst += dst_stride; 108 } 109 vst1_u8((uint8_t*)tmp, mask8); 110 alpha_mask *= 0x01010101; 111 alpha_mask &= tmp[0]; 112 alpha_mask &= tmp[1]; 113 return (alpha_mask != 0xffffffffu); 114 } 115 116 static void DispatchAlphaToGreen_NEON(const uint8_t* WEBP_RESTRICT alpha, 117 int alpha_stride, int width, int height, 118 uint32_t* WEBP_RESTRICT dst, 119 int dst_stride) { 120 int i, j; 121 uint8x8x4_t greens; // leave A/R/B channels zero'd. 122 greens.val[0] = vdup_n_u8(0); 123 greens.val[2] = vdup_n_u8(0); 124 greens.val[3] = vdup_n_u8(0); 125 for (j = 0; j < height; ++j) { 126 for (i = 0; i + 8 <= width; i += 8) { 127 greens.val[1] = vld1_u8(alpha + i); 128 vst4_u8((uint8_t*)(dst + i), greens); 129 } 130 for (; i < width; ++i) dst[i] = alpha[i] << 8; 131 alpha += alpha_stride; 132 dst += dst_stride; 133 } 134 } 135 136 static int ExtractAlpha_NEON(const uint8_t* WEBP_RESTRICT argb, int argb_stride, 137 int width, int height, 138 uint8_t* WEBP_RESTRICT alpha, int alpha_stride) { 139 uint32_t alpha_mask = 0xffu; 140 uint8x8_t mask8 = vdup_n_u8(0xff); 141 uint32_t tmp[2]; 142 int i, j; 143 for (j = 0; j < height; ++j) { 144 // We don't know if alpha is first or last in dst[] (depending on rgbA/Argb 145 // mode). So we must be sure dst[4*i + 8 - 1] is writable for the store. 146 // Hence the test with 'width - 1' instead of just 'width'. 147 for (i = 0; i + 8 <= width - 1; i += 8) { 148 const uint8x8x4_t rgbX = vld4_u8((const uint8_t*)(argb + 4 * i)); 149 const uint8x8_t alphas = rgbX.val[0]; 150 vst1_u8((uint8_t*)(alpha + i), alphas); 151 mask8 = vand_u8(mask8, alphas); 152 } 153 for (; i < width; ++i) { 154 alpha[i] = argb[4 * i]; 155 alpha_mask &= alpha[i]; 156 } 157 argb += argb_stride; 158 alpha += alpha_stride; 159 } 160 vst1_u8((uint8_t*)tmp, mask8); 161 alpha_mask *= 0x01010101; 162 alpha_mask &= tmp[0]; 163 alpha_mask &= tmp[1]; 164 return (alpha_mask == 0xffffffffu); 165 } 166 167 static void ExtractGreen_NEON(const uint32_t* WEBP_RESTRICT argb, 168 uint8_t* WEBP_RESTRICT alpha, int size) { 169 int i; 170 for (i = 0; i + 16 <= size; i += 16) { 171 const uint8x16x4_t rgbX = vld4q_u8((const uint8_t*)(argb + i)); 172 const uint8x16_t greens = rgbX.val[1]; 173 vst1q_u8(alpha + i, greens); 174 } 175 for (; i < size; ++i) alpha[i] = (argb[i] >> 8) & 0xff; 176 } 177 178 //------------------------------------------------------------------------------ 179 180 extern void WebPInitAlphaProcessingNEON(void); 181 182 WEBP_TSAN_IGNORE_FUNCTION void WebPInitAlphaProcessingNEON(void) { 183 WebPApplyAlphaMultiply = ApplyAlphaMultiply_NEON; 184 WebPDispatchAlpha = DispatchAlpha_NEON; 185 WebPDispatchAlphaToGreen = DispatchAlphaToGreen_NEON; 186 WebPExtractAlpha = ExtractAlpha_NEON; 187 WebPExtractGreen = ExtractGreen_NEON; 188 } 189 190 #else // !WEBP_USE_NEON 191 192 WEBP_DSP_INIT_STUB(WebPInitAlphaProcessingNEON) 193 194 #endif // WEBP_USE_NEON