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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 5 #ifndef CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
6 #define CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 6 #define CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
7 | 7 |
8 #include "cc/resources/texture_compressor.h" | 8 #include "cc/resources/texture_compressor.h" |
9 | 9 |
| 10 #include "base/compiler_specific.h" |
| 11 #include "base/logging.h" |
| 12 |
10 namespace cc { | 13 namespace cc { |
11 | 14 |
| 15 template <typename T> |
| 16 inline T clamp(T val, T min, T max) { |
| 17 return val < min ? min : (val > max ? max : val); |
| 18 } |
| 19 |
| 20 inline uint8_t round_to_5_bits(float val) { |
| 21 return clamp<uint8_t>(val * 31.0f / 255.0f + 0.5f, 0, 31); |
| 22 } |
| 23 |
| 24 inline uint8_t round_to_4_bits(float val) { |
| 25 return clamp<uint8_t>(val * 15.0f / 255.0f + 0.5f, 0, 15); |
| 26 } |
| 27 |
| 28 union Color { |
| 29 struct BgraColorType { |
| 30 uint8_t b; |
| 31 uint8_t g; |
| 32 uint8_t r; |
| 33 uint8_t a; |
| 34 } channels; |
| 35 uint8_t components[4]; |
| 36 uint32_t bits; |
| 37 }; |
| 38 |
| 39 // Codeword tables. |
| 40 // See: Table 3.17.2 |
| 41 ALIGNAS(16) static const int16_t g_codeword_tables[8][4] = { |
| 42 {-8, -2, 2, 8}, |
| 43 {-17, -5, 5, 17}, |
| 44 {-29, -9, 9, 29}, |
| 45 {-42, -13, 13, 42}, |
| 46 {-60, -18, 18, 60}, |
| 47 {-80, -24, 24, 80}, |
| 48 {-106, -33, 33, 106}, |
| 49 {-183, -47, 47, 183}}; |
| 50 |
| 51 // Maps modifier indices to pixel index values. |
| 52 // See: Table 3.17.3 |
| 53 static const uint8_t g_mod_to_pix[4] = {3, 2, 0, 1}; |
| 54 |
| 55 // The ETC1 specification index texels as follows: |
| 56 // [a][e][i][m] [ 0][ 4][ 8][12] |
| 57 // [b][f][j][n] <-> [ 1][ 5][ 9][13] |
| 58 // [c][g][k][o] [ 2][ 6][10][14] |
| 59 // [d][h][l][p] [ 3][ 7][11][15] |
| 60 |
| 61 // [ 0][ 1][ 2][ 3] [ 0][ 1][ 4][ 5] |
| 62 // [ 4][ 5][ 6][ 7] <-> [ 8][ 9][12][13] |
| 63 // [ 8][ 9][10][11] [ 2][ 3][ 6][ 7] |
| 64 // [12][13][14][15] [10][11][14][15] |
| 65 |
| 66 // However, when extracting sub blocks from BGRA data the natural array |
| 67 // indexing order ends up different: |
| 68 // vertical0: [a][e][b][f] horizontal0: [a][e][i][m] |
| 69 // [c][g][d][h] [b][f][j][n] |
| 70 // vertical1: [i][m][j][n] horizontal1: [c][g][k][o] |
| 71 // [k][o][l][p] [d][h][l][p] |
| 72 |
| 73 // In order to translate from the natural array indices in a sub block to the |
| 74 // indices (number) used by specification and hardware we use this table. |
| 75 static const uint8_t g_idx_to_num[4][8] = { |
| 76 {0, 4, 1, 5, 2, 6, 3, 7}, // Vertical block 0. |
| 77 {8, 12, 9, 13, 10, 14, 11, 15}, // Vertical block 1. |
| 78 {0, 4, 8, 12, 1, 5, 9, 13}, // Horizontal block 0. |
| 79 {2, 6, 10, 14, 3, 7, 11, 15} // Horizontal block 1. |
| 80 }; |
| 81 |
| 82 inline void WriteColors444(uint8_t* block, |
| 83 const Color& color0, |
| 84 const Color& color1) { |
| 85 // Write output color for BGRA textures. |
| 86 block[0] = (color0.channels.r & 0xf0) | (color1.channels.r >> 4); |
| 87 block[1] = (color0.channels.g & 0xf0) | (color1.channels.g >> 4); |
| 88 block[2] = (color0.channels.b & 0xf0) | (color1.channels.b >> 4); |
| 89 } |
| 90 |
| 91 inline void WriteColors555(uint8_t* block, |
| 92 const Color& color0, |
| 93 const Color& color1) { |
| 94 // Table for conversion to 3-bit two complement format. |
| 95 static const uint8_t two_compl_trans_table[8] = { |
| 96 4, // -4 (100b) |
| 97 5, // -3 (101b) |
| 98 6, // -2 (110b) |
| 99 7, // -1 (111b) |
| 100 0, // 0 (000b) |
| 101 1, // 1 (001b) |
| 102 2, // 2 (010b) |
| 103 3, // 3 (011b) |
| 104 }; |
| 105 |
| 106 int16_t delta_r = |
| 107 static_cast<int16_t>(color1.channels.r >> 3) - (color0.channels.r >> 3); |
| 108 int16_t delta_g = |
| 109 static_cast<int16_t>(color1.channels.g >> 3) - (color0.channels.g >> 3); |
| 110 int16_t delta_b = |
| 111 static_cast<int16_t>(color1.channels.b >> 3) - (color0.channels.b >> 3); |
| 112 DCHECK_GE(delta_r, -4); |
| 113 DCHECK_LE(delta_r, 3); |
| 114 DCHECK_GE(delta_g, -4); |
| 115 DCHECK_LE(delta_g, 3); |
| 116 DCHECK_GE(delta_b, -4); |
| 117 DCHECK_LE(delta_b, 3); |
| 118 |
| 119 // Write output color for BGRA textures. |
| 120 block[0] = (color0.channels.r & 0xf8) | two_compl_trans_table[delta_r + 4]; |
| 121 block[1] = (color0.channels.g & 0xf8) | two_compl_trans_table[delta_g + 4]; |
| 122 block[2] = (color0.channels.b & 0xf8) | two_compl_trans_table[delta_b + 4]; |
| 123 } |
| 124 |
| 125 inline void WriteCodewordTable(uint8_t* block, |
| 126 uint8_t sub_block_id, |
| 127 uint8_t table) { |
| 128 DCHECK_LT(sub_block_id, 2); |
| 129 DCHECK_LT(table, 8); |
| 130 |
| 131 uint8_t shift = (2 + (3 - sub_block_id * 3)); |
| 132 block[3] &= ~(0x07 << shift); |
| 133 block[3] |= table << shift; |
| 134 } |
| 135 |
| 136 inline void WritePixelData(uint8_t* block, uint32_t pixel_data) { |
| 137 block[4] |= pixel_data >> 24; |
| 138 block[5] |= (pixel_data >> 16) & 0xff; |
| 139 block[6] |= (pixel_data >> 8) & 0xff; |
| 140 block[7] |= pixel_data & 0xff; |
| 141 } |
| 142 |
| 143 inline void WriteFlip(uint8_t* block, bool flip) { |
| 144 block[3] &= ~0x01; |
| 145 block[3] |= static_cast<uint8_t>(flip); |
| 146 } |
| 147 |
| 148 inline void WriteDiff(uint8_t* block, bool diff) { |
| 149 block[3] &= ~0x02; |
| 150 block[3] |= static_cast<uint8_t>(diff) << 1; |
| 151 } |
| 152 |
| 153 // Compress and rounds BGR888 into BGR444. The resulting BGR444 color is |
| 154 // expanded to BGR888 as it would be in hardware after decompression. The |
| 155 // actual 444-bit data is available in the four most significant bits of each |
| 156 // channel. |
| 157 inline Color MakeColor444(const float* bgr) { |
| 158 uint8_t b4 = round_to_4_bits(bgr[0]); |
| 159 uint8_t g4 = round_to_4_bits(bgr[1]); |
| 160 uint8_t r4 = round_to_4_bits(bgr[2]); |
| 161 Color bgr444; |
| 162 bgr444.channels.b = (b4 << 4) | b4; |
| 163 bgr444.channels.g = (g4 << 4) | g4; |
| 164 bgr444.channels.r = (r4 << 4) | r4; |
| 165 // Added to distinguish between expanded 555 and 444 colors. |
| 166 bgr444.channels.a = 0x44; |
| 167 return bgr444; |
| 168 } |
| 169 |
| 170 // Compress and rounds BGR888 into BGR555. The resulting BGR555 color is |
| 171 // expanded to BGR888 as it would be in hardware after decompression. The |
| 172 // actual 555-bit data is available in the five most significant bits of each |
| 173 // channel. |
| 174 inline Color MakeColor555(const float* bgr) { |
| 175 uint8_t b5 = round_to_5_bits(bgr[0]); |
| 176 uint8_t g5 = round_to_5_bits(bgr[1]); |
| 177 uint8_t r5 = round_to_5_bits(bgr[2]); |
| 178 Color bgr555; |
| 179 bgr555.channels.b = (b5 << 3) | (b5 >> 2); |
| 180 bgr555.channels.g = (g5 << 3) | (g5 >> 2); |
| 181 bgr555.channels.r = (r5 << 3) | (r5 >> 2); |
| 182 // Added to distinguish between expanded 555 and 444 colors. |
| 183 bgr555.channels.a = 0x55; |
| 184 return bgr555; |
| 185 } |
| 186 |
12 class CC_EXPORT TextureCompressorETC1 : public TextureCompressor { | 187 class CC_EXPORT TextureCompressorETC1 : public TextureCompressor { |
13 public: | 188 public: |
14 TextureCompressorETC1() {} | 189 TextureCompressorETC1() {} |
15 | 190 |
16 // Compress a texture using ETC1. Note that the |quality| parameter is | 191 // Compress a texture using ETC1. Note that the |quality| parameter is |
17 // ignored. The current implementation does not support different quality | 192 // ignored. The current implementation does not support different quality |
18 // settings. | 193 // settings. |
19 void Compress(const uint8_t* src, | 194 void Compress(const uint8_t* src, |
20 uint8_t* dst, | 195 uint8_t* dst, |
21 int width, | 196 int width, |
22 int height, | 197 int height, |
23 Quality quality) override; | 198 Quality quality) override; |
24 | 199 |
25 private: | 200 private: |
26 DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1); | 201 DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1); |
27 }; | 202 }; |
28 | 203 |
29 } // namespace cc | 204 } // namespace cc |
30 | 205 |
31 #endif // CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 206 #endif // CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
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