| // Copyright 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CC_RASTER_TEXTURE_COMPRESSOR_ETC1_H_ |
| #define CC_RASTER_TEXTURE_COMPRESSOR_ETC1_H_ |
| |
| #include "cc/raster/texture_compressor.h" |
| |
| #include <stdint.h> |
| |
| #include "base/compiler_specific.h" |
| #include "base/logging.h" |
| #include "base/macros.h" |
| |
| namespace cc { |
| |
| template <typename T> |
| inline T clamp(T val, T min, T max) { |
| return val < min ? min : (val > max ? max : val); |
| } |
| |
| inline uint8_t round_to_5_bits(float val) { |
| return clamp<uint8_t>(val * 31.0f / 255.0f + 0.5f, 0, 31); |
| } |
| |
| inline uint8_t round_to_4_bits(float val) { |
| return clamp<uint8_t>(val * 15.0f / 255.0f + 0.5f, 0, 15); |
| } |
| |
| union Color { |
| struct BgraColorType { |
| uint8_t b; |
| uint8_t g; |
| uint8_t r; |
| uint8_t a; |
| } channels; |
| uint8_t components[4]; |
| uint32_t bits; |
| }; |
| |
| // Codeword tables. |
| // See: Table 3.17.2 |
| alignas(16) static const int16_t g_codeword_tables[8][4] = { |
| {-8, -2, 2, 8}, {-17, -5, 5, 17}, {-29, -9, 9, 29}, |
| {-42, -13, 13, 42}, {-60, -18, 18, 60}, {-80, -24, 24, 80}, |
| {-106, -33, 33, 106}, {-183, -47, 47, 183}}; |
| |
| // Maps modifier indices to pixel index values. |
| // See: Table 3.17.3 |
| static const uint8_t g_mod_to_pix[4] = {3, 2, 0, 1}; |
| |
| // The ETC1 specification index texels as follows: |
| // [a][e][i][m] [ 0][ 4][ 8][12] |
| // [b][f][j][n] <-> [ 1][ 5][ 9][13] |
| // [c][g][k][o] [ 2][ 6][10][14] |
| // [d][h][l][p] [ 3][ 7][11][15] |
| |
| // [ 0][ 1][ 2][ 3] [ 0][ 1][ 4][ 5] |
| // [ 4][ 5][ 6][ 7] <-> [ 8][ 9][12][13] |
| // [ 8][ 9][10][11] [ 2][ 3][ 6][ 7] |
| // [12][13][14][15] [10][11][14][15] |
| |
| // However, when extracting sub blocks from BGRA data the natural array |
| // indexing order ends up different: |
| // vertical0: [a][e][b][f] horizontal0: [a][e][i][m] |
| // [c][g][d][h] [b][f][j][n] |
| // vertical1: [i][m][j][n] horizontal1: [c][g][k][o] |
| // [k][o][l][p] [d][h][l][p] |
| |
| // In order to translate from the natural array indices in a sub block to the |
| // indices (number) used by specification and hardware we use this table. |
| static const uint8_t g_idx_to_num[4][8] = { |
| {0, 4, 1, 5, 2, 6, 3, 7}, // Vertical block 0. |
| {8, 12, 9, 13, 10, 14, 11, 15}, // Vertical block 1. |
| {0, 4, 8, 12, 1, 5, 9, 13}, // Horizontal block 0. |
| {2, 6, 10, 14, 3, 7, 11, 15} // Horizontal block 1. |
| }; |
| |
| inline void WriteColors444(uint8_t* block, |
| const Color& color0, |
| const Color& color1) { |
| // Write output color for BGRA textures. |
| block[0] = (color0.channels.r & 0xf0) | (color1.channels.r >> 4); |
| block[1] = (color0.channels.g & 0xf0) | (color1.channels.g >> 4); |
| block[2] = (color0.channels.b & 0xf0) | (color1.channels.b >> 4); |
| } |
| |
| inline void WriteColors555(uint8_t* block, |
| const Color& color0, |
| const Color& color1) { |
| // Table for conversion to 3-bit two complement format. |
| static const uint8_t two_compl_trans_table[8] = { |
| 4, // -4 (100b) |
| 5, // -3 (101b) |
| 6, // -2 (110b) |
| 7, // -1 (111b) |
| 0, // 0 (000b) |
| 1, // 1 (001b) |
| 2, // 2 (010b) |
| 3, // 3 (011b) |
| }; |
| |
| int16_t delta_r = |
| static_cast<int16_t>(color1.channels.r >> 3) - (color0.channels.r >> 3); |
| int16_t delta_g = |
| static_cast<int16_t>(color1.channels.g >> 3) - (color0.channels.g >> 3); |
| int16_t delta_b = |
| static_cast<int16_t>(color1.channels.b >> 3) - (color0.channels.b >> 3); |
| DCHECK_GE(delta_r, -4); |
| DCHECK_LE(delta_r, 3); |
| DCHECK_GE(delta_g, -4); |
| DCHECK_LE(delta_g, 3); |
| DCHECK_GE(delta_b, -4); |
| DCHECK_LE(delta_b, 3); |
| |
| // Write output color for BGRA textures. |
| block[0] = (color0.channels.r & 0xf8) | two_compl_trans_table[delta_r + 4]; |
| block[1] = (color0.channels.g & 0xf8) | two_compl_trans_table[delta_g + 4]; |
| block[2] = (color0.channels.b & 0xf8) | two_compl_trans_table[delta_b + 4]; |
| } |
| |
| inline void WriteCodewordTable(uint8_t* block, |
| uint8_t sub_block_id, |
| uint8_t table) { |
| DCHECK_LT(sub_block_id, 2); |
| DCHECK_LT(table, 8); |
| |
| uint8_t shift = (2 + (3 - sub_block_id * 3)); |
| block[3] &= ~(0x07 << shift); |
| block[3] |= table << shift; |
| } |
| |
| inline void WritePixelData(uint8_t* block, uint32_t pixel_data) { |
| block[4] |= pixel_data >> 24; |
| block[5] |= (pixel_data >> 16) & 0xff; |
| block[6] |= (pixel_data >> 8) & 0xff; |
| block[7] |= pixel_data & 0xff; |
| } |
| |
| inline void WriteFlip(uint8_t* block, bool flip) { |
| block[3] &= ~0x01; |
| block[3] |= static_cast<uint8_t>(flip); |
| } |
| |
| inline void WriteDiff(uint8_t* block, bool diff) { |
| block[3] &= ~0x02; |
| block[3] |= static_cast<uint8_t>(diff) << 1; |
| } |
| |
| // Compress and rounds BGR888 into BGR444. The resulting BGR444 color is |
| // expanded to BGR888 as it would be in hardware after decompression. The |
| // actual 444-bit data is available in the four most significant bits of each |
| // channel. |
| inline Color MakeColor444(const float* bgr) { |
| uint8_t b4 = round_to_4_bits(bgr[0]); |
| uint8_t g4 = round_to_4_bits(bgr[1]); |
| uint8_t r4 = round_to_4_bits(bgr[2]); |
| Color bgr444; |
| bgr444.channels.b = (b4 << 4) | b4; |
| bgr444.channels.g = (g4 << 4) | g4; |
| bgr444.channels.r = (r4 << 4) | r4; |
| // Added to distinguish between expanded 555 and 444 colors. |
| bgr444.channels.a = 0x44; |
| return bgr444; |
| } |
| |
| // Compress and rounds BGR888 into BGR555. The resulting BGR555 color is |
| // expanded to BGR888 as it would be in hardware after decompression. The |
| // actual 555-bit data is available in the five most significant bits of each |
| // channel. |
| inline Color MakeColor555(const float* bgr) { |
| uint8_t b5 = round_to_5_bits(bgr[0]); |
| uint8_t g5 = round_to_5_bits(bgr[1]); |
| uint8_t r5 = round_to_5_bits(bgr[2]); |
| Color bgr555; |
| bgr555.channels.b = (b5 << 3) | (b5 >> 2); |
| bgr555.channels.g = (g5 << 3) | (g5 >> 2); |
| bgr555.channels.r = (r5 << 3) | (r5 >> 2); |
| // Added to distinguish between expanded 555 and 444 colors. |
| bgr555.channels.a = 0x55; |
| return bgr555; |
| } |
| |
| class CC_EXPORT TextureCompressorETC1 : public TextureCompressor { |
| public: |
| TextureCompressorETC1() {} |
| |
| // Compress a texture using ETC1. Note that the |quality| parameter is |
| // ignored. The current implementation does not support different quality |
| // settings. |
| void Compress(const uint8_t* src, |
| uint8_t* dst, |
| int width, |
| int height, |
| Quality quality) override; |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1); |
| }; |
| |
| } // namespace cc |
| |
| #endif // CC_RASTER_TEXTURE_COMPRESSOR_ETC1_H_ |