91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
#include "bcn.h"
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#include "atc.h"
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#include "color.h"
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#include <algorithm>
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static uint8_t expand_quantized(uint8_t v, int bits) {
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v = v << (8 - bits);
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return v | (v >> bits);
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}
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void decode_atc_block(const uint8_t* _src, uint32_t* _dst)
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{
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uint8_t colors[4 * 4];
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uint32_t c0 = _src[0] | (_src[1] << 8);
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uint32_t c1 = _src[2] | (_src[3] << 8);
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if (0 == (c0 & 0x8000))
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{
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colors[0] = expand_quantized((c0 >> 0) & 0x1f, 5);
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colors[1] = expand_quantized((c0 >> 5) & 0x1f, 5);
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colors[2] = expand_quantized((c0 >> 10) & 0x1f, 5);
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colors[12] = expand_quantized((c1 >> 0) & 0x1f, 5);
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colors[13] = expand_quantized((c1 >> 5) & 0x3f, 6);
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colors[14] = expand_quantized((c1 >> 11) & 0x1f, 5);
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colors[4] = (5 * colors[0] + 3 * colors[12]) / 8;
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colors[5] = (5 * colors[1] + 3 * colors[13]) / 8;
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colors[6] = (5 * colors[2] + 3 * colors[14]) / 8;
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colors[8] = (3 * colors[0] + 5 * colors[12]) / 8;
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colors[9] = (3 * colors[1] + 5 * colors[13]) / 8;
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colors[10] = (3 * colors[2] + 5 * colors[14]) / 8;
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}
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else
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{
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colors[0] = 0;
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colors[1] = 0;
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colors[2] = 0;
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colors[8] = expand_quantized((c0 >> 0) & 0x1f, 5);
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colors[9] = expand_quantized((c0 >> 5) & 0x1f, 5);
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colors[10] = expand_quantized((c0 >> 10) & 0x1f, 5);
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colors[12] = expand_quantized((c1 >> 0) & 0x1f, 5);
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colors[13] = expand_quantized((c1 >> 5) & 0x3f, 6);
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colors[14] = expand_quantized((c1 >> 11) & 0x1f, 5);
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colors[4] = std::max(0, colors[8] - colors[12] / 4);
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colors[5] = std::max(0, colors[9] - colors[13] / 4);
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colors[6] = std::max(0, colors[10] - colors[14] / 4);
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}
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for (uint32_t i = 0, next = 8 * 4; i < 16; i += 1, next += 2)
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{
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int32_t idx = ((_src[next >> 3] >> (next & 7)) & 3) * 4;
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_dst[i] = color(colors[idx + 2], colors[idx + 1], colors[idx + 0], 255);
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}
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}
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int decode_atc_rgb4(const uint8_t* data, uint32_t m_width, uint32_t m_height, uint32_t* image) {
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uint32_t m_block_width = 4;
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uint32_t m_block_height = 4;
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uint32_t m_blocks_x = (m_width + m_block_width - 1) / m_block_width;
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uint32_t m_blocks_y = (m_height + m_block_height - 1) / m_block_height;
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uint32_t buffer[16];
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for (uint32_t by = 0; by < m_blocks_y; by++) {
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for (uint32_t bx = 0; bx < m_blocks_x; bx++, data += 8) {
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decode_atc_block(data, buffer);
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copy_block_buffer(bx, by, m_width, m_height, m_block_width, m_block_height, buffer, image);
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}
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}
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return 1;
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}
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int decode_atc_rgba8(const uint8_t* data, uint32_t m_width, uint32_t m_height, uint32_t* image) {
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uint32_t m_block_width = 4;
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uint32_t m_block_height = 4;
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uint32_t m_blocks_x = (m_width + m_block_width - 1) / m_block_width;
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uint32_t m_blocks_y = (m_height + m_block_height - 1) / m_block_height;
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uint32_t buffer[16];
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for (uint32_t by = 0; by < m_blocks_y; by++) {
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for (uint32_t bx = 0; bx < m_blocks_x; bx++, data += 16) {
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decode_atc_block(data + 8, buffer);
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decode_bc3_alpha(data, buffer, 3);
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copy_block_buffer(bx, by, m_width, m_height, m_block_width, m_block_height, buffer, image);
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}
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}
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return 1;
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} |