forked from suyu/suyu
98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
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// Copyright 2020 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <algorithm>
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#include <array>
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#include <span>
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#include "common/assert.h"
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#include "common/common_types.h"
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#include "video_core/texture_cache/decode_bc4.h"
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#include "video_core/texture_cache/types.h"
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namespace VideoCommon {
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// https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_texture_compression_rgtc.txt
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[[nodiscard]] constexpr u32 DecompressBlock(u64 bits, u32 x, u32 y) {
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const u32 code_offset = 16 + 3 * (4 * y + x);
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const u32 code = (bits >> code_offset) & 7;
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const u32 red0 = (bits >> 0) & 0xff;
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const u32 red1 = (bits >> 8) & 0xff;
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if (red0 > red1) {
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switch (code) {
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case 0:
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return red0;
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case 1:
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return red1;
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case 2:
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return (6 * red0 + 1 * red1) / 7;
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case 3:
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return (5 * red0 + 2 * red1) / 7;
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case 4:
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return (4 * red0 + 3 * red1) / 7;
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case 5:
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return (3 * red0 + 4 * red1) / 7;
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case 6:
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return (2 * red0 + 5 * red1) / 7;
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case 7:
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return (1 * red0 + 6 * red1) / 7;
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}
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} else {
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switch (code) {
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case 0:
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return red0;
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case 1:
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return red1;
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case 2:
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return (4 * red0 + 1 * red1) / 5;
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case 3:
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return (3 * red0 + 2 * red1) / 5;
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case 4:
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return (2 * red0 + 3 * red1) / 5;
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case 5:
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return (1 * red0 + 4 * red1) / 5;
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case 6:
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return 0;
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case 7:
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return 0xff;
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}
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}
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return 0;
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}
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void DecompressBC4(std::span<const u8> input, Extent3D extent, std::span<u8> output) {
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UNIMPLEMENTED_IF_MSG(extent.width % 4 != 0, "Unaligned width={}", extent.width);
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UNIMPLEMENTED_IF_MSG(extent.height % 4 != 0, "Unaligned height={}", extent.height);
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static constexpr u32 BLOCK_SIZE = 4;
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size_t input_offset = 0;
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for (u32 slice = 0; slice < extent.depth; ++slice) {
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for (u32 block_y = 0; block_y < extent.height / 4; ++block_y) {
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for (u32 block_x = 0; block_x < extent.width / 4; ++block_x) {
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u64 bits;
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std::memcpy(&bits, &input[input_offset], sizeof(bits));
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input_offset += sizeof(bits);
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for (u32 y = 0; y < BLOCK_SIZE; ++y) {
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for (u32 x = 0; x < BLOCK_SIZE; ++x) {
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const u32 linear_z = slice;
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const u32 linear_y = block_y * BLOCK_SIZE + y;
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const u32 linear_x = block_x * BLOCK_SIZE + x;
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const u32 offset_z = linear_z * extent.width * extent.height;
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const u32 offset_y = linear_y * extent.width;
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const u32 offset_x = linear_x;
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const u32 output_offset = (offset_z + offset_y + offset_x) * 4ULL;
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const u32 color = DecompressBlock(bits, x, y);
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output[output_offset + 0] = static_cast<u8>(color);
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output[output_offset + 1] = 0;
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output[output_offset + 2] = 0;
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output[output_offset + 3] = 0xff;
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}
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}
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}
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}
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}
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}
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} // namespace VideoCommon
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