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1// SPDX-License-Identifier: MPL-2.0
2// Copyright © 2022 Skyline Team and Contributors (https://github.com/skyline-emu/)
3// Copyright 2019 The SwiftShader Authors. All Rights Reserved.
4
5// This BCn Decoder is directly derivative of Swiftshader's BCn Decoder found at: https://github.com/google/swiftshader/blob/d070309f7d154d6764cbd514b1a5c8bfcef61d06/src/Device/BC_Decoder.cpp
6// This file does not follow the Skyline code conventions but has certain Skyline specific code
7// There are a lot of implicit and narrowing conversions in this file due to this (Warnings are disabled as a result)
8
9#include <array>
10#include <assert.h>
11#include <stddef.h>
12#include <stdint.h>
13
14namespace {
15 constexpr int BlockWidth = 4;
16 constexpr int BlockHeight = 4;
17
18 struct BC_color {
19 void decode(uint8_t *dst, size_t x, size_t y, size_t dstW, size_t dstH, size_t dstPitch, size_t dstBpp, bool hasAlphaChannel, bool hasSeparateAlpha) const {
20 Color c[4];
21 c[0].extract565(c0);
22 c[1].extract565(c1);
23 if (hasSeparateAlpha || (c0 > c1)) {
24 c[2] = ((c[0] * 2) + c[1]) / 3;
25 c[3] = ((c[1] * 2) + c[0]) / 3;
26 } else {
27 c[2] = (c[0] + c[1]) >> 1;
28 if (hasAlphaChannel) {
29 c[3].clearAlpha();
30 }
31 }
32
33 for (int j = 0; j < BlockHeight && (y + j) < dstH; j++) {
34 size_t dstOffset = j * dstPitch;
35 size_t idxOffset = j * BlockHeight;
36 for (size_t i = 0; i < BlockWidth && (x + i) < dstW; i++, idxOffset++, dstOffset += dstBpp) {
37 *reinterpret_cast<unsigned int *>(dst + dstOffset) = c[getIdx(idxOffset)].pack8888();
38 }
39 }
40 }
41
42 private:
43 struct Color {
44 Color() {
45 c[0] = c[1] = c[2] = 0;
46 c[3] = 0xFF000000;
47 }
48
49 void extract565(const unsigned int c565) {
50 c[0] = ((c565 & 0x0000001F) << 3) | ((c565 & 0x0000001C) >> 2);
51 c[1] = ((c565 & 0x000007E0) >> 3) | ((c565 & 0x00000600) >> 9);
52 c[2] = ((c565 & 0x0000F800) >> 8) | ((c565 & 0x0000E000) >> 13);
53 }
54
55 unsigned int pack8888() const {
56 return ((c[0] & 0xFF) << 16) | ((c[1] & 0xFF) << 8) | (c[2] & 0xFF) | c[3];
57 }
58
59 void clearAlpha() {
60 c[3] = 0;
61 }
62
63 Color operator*(int factor) const {
64 Color res;
65 for (int i = 0; i < 4; ++i) {
66 res.c[i] = c[i] * factor;
67 }
68 return res;
69 }
70
71 Color operator/(int factor) const {
72 Color res;
73 for (int i = 0; i < 4; ++i) {
74 res.c[i] = c[i] / factor;
75 }
76 return res;
77 }
78
79 Color operator>>(int shift) const {
80 Color res;
81 for (int i = 0; i < 4; ++i) {
82 res.c[i] = c[i] >> shift;
83 }
84 return res;
85 }
86
87 Color operator+(Color const &obj) const {
88 Color res;
89 for (int i = 0; i < 4; ++i) {
90 res.c[i] = c[i] + obj.c[i];
91 }
92 return res;
93 }
94
95 private:
96 int c[4];
97 };
98
99 size_t getIdx(int i) const {
100 size_t offset = i << 1; // 2 bytes per index
101 return (idx & (0x3 << offset)) >> offset;
102 }
103
104 unsigned short c0;
105 unsigned short c1;
106 unsigned int idx;
107 };
108 static_assert(sizeof(BC_color) == 8, "BC_color must be 8 bytes");
109
110 struct BC_channel {
111 void decode(uint8_t *dst, size_t x, size_t y, size_t dstW, size_t dstH, size_t dstPitch, size_t dstBpp, size_t channel, bool isSigned) const {
112 int c[8] = {0};
113
114 if (isSigned) {
115 c[0] = static_cast<signed char>(data & 0xFF);
116 c[1] = static_cast<signed char>((data & 0xFF00) >> 8);
117 } else {
118 c[0] = static_cast<uint8_t>(data & 0xFF);
119 c[1] = static_cast<uint8_t>((data & 0xFF00) >> 8);
120 }
121
122 if (c[0] > c[1]) {
123 for (int i = 2; i < 8; ++i) {
124 c[i] = ((8 - i) * c[0] + (i - 1) * c[1]) / 7;
125 }
126 } else {
127 for (int i = 2; i < 6; ++i) {
128 c[i] = ((6 - i) * c[0] + (i - 1) * c[1]) / 5;
129 }
130 c[6] = isSigned ? -128 : 0;
131 c[7] = isSigned ? 127 : 255;
132 }
133
134 for (size_t j = 0; j < BlockHeight && (y + j) < dstH; j++) {
135 for (size_t i = 0; i < BlockWidth && (x + i) < dstW; i++) {
136 dst[channel + (i * dstBpp) + (j * dstPitch)] = static_cast<uint8_t>(c[getIdx((j * BlockHeight) + i)]);
137 }
138 }
139 }
140
141 private:
142 uint8_t getIdx(int i) const {
143 int offset = i * 3 + 16;
144 return static_cast<uint8_t>((data & (0x7ull << offset)) >> offset);
145 }
146
147 uint64_t data;
148 };
149 static_assert(sizeof(BC_channel) == 8, "BC_channel must be 8 bytes");
150
151 struct BC_alpha {
152 void decode(uint8_t *dst, size_t x, size_t y, size_t dstW, size_t dstH, size_t dstPitch, size_t dstBpp) const {
153 dst += 3; // Write only to alpha (channel 3)
154 for (size_t j = 0; j < BlockHeight && (y + j) < dstH; j++, dst += dstPitch) {
155 uint8_t *dstRow = dst;
156 for (size_t i = 0; i < BlockWidth && (x + i) < dstW; i++, dstRow += dstBpp) {
157 *dstRow = getAlpha(j * BlockHeight + i);
158 }
159 }
160 }
161
162 private:
163 uint8_t getAlpha(int i) const {
164 int offset = i << 2;
165 int alpha = (data & (0xFull << offset)) >> offset;
166 return static_cast<uint8_t>(alpha | (alpha << 4));
167 }
168
169 uint64_t data;
170 };
171 static_assert(sizeof(BC_alpha) == 8, "BC_alpha must be 8 bytes");
172
173 namespace BC6H {
174 static constexpr int MaxPartitions = 64;
175
176 // @fmt:off
177
178 static constexpr uint8_t PartitionTable2[MaxPartitions][16] = {
179 { 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1 },
180 { 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1 },
181 { 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1 },
182 { 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1 },
183 { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1 },
184 { 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1 },
185 { 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1 },
186 { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1 },
187 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1 },
188 { 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
189 { 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1 },
190 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1 },
191 { 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
192 { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1 },
193 { 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
194 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1 },
195 { 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1 },
196 { 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0 },
197 { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0 },
198 { 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0 },
199 { 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0 },
200 { 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0 },
201 { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0 },
202 { 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1 },
203 { 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0 },
204 { 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0 },
205 { 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0 },
206 { 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0 },
207 { 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0 },
208 { 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0 },
209 { 0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0 },
210 { 0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0 },
211 { 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 },
212 { 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1 },
213 { 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0 },
214 { 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0 },
215 { 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0 },
216 { 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0 },
217 { 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1 },
218 { 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1 },
219 { 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0 },
220 { 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0 },
221 { 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0 },
222 { 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 0 },
223 { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 },
224 { 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1 },
225 { 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1 },
226 { 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0 },
227 { 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0 },
228 { 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0 },
229 { 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0 },
230 { 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0 },
231 { 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1 },
232 { 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1 },
233 { 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0 },
234 { 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0 },
235 { 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1 },
236 { 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1 },
237 { 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1 },
238 { 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1 },
239 { 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1 },
240 { 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0 },
241 { 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0 },
242 { 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1 },
243 };
244
245 static constexpr uint8_t AnchorTable2[MaxPartitions] = {
246 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf,
247 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf,
248 0xf, 0x2, 0x8, 0x2, 0x2, 0x8, 0x8, 0xf,
249 0x2, 0x8, 0x2, 0x2, 0x8, 0x8, 0x2, 0x2,
250 0xf, 0xf, 0x6, 0x8, 0x2, 0x8, 0xf, 0xf,
251 0x2, 0x8, 0x2, 0x2, 0x2, 0xf, 0xf, 0x6,
252 0x6, 0x2, 0x6, 0x8, 0xf, 0xf, 0x2, 0x2,
253 0xf, 0xf, 0xf, 0xf, 0xf, 0x2, 0x2, 0xf,
254 };
255
256 // @fmt:on
257
258 // 1.0f in half-precision floating point format
259 static constexpr uint16_t halfFloat1 = 0x3C00;
260 union Color {
261 struct RGBA {
262 uint16_t r = 0;
263 uint16_t g = 0;
264 uint16_t b = 0;
265 uint16_t a = halfFloat1;
266
267 RGBA(uint16_t r, uint16_t g, uint16_t b)
268 : r(r), g(g), b(b) {
269 }
270
271 RGBA &operator=(const RGBA &other) {
272 this->r = other.r;
273 this->g = other.g;
274 this->b = other.b;
275 this->a = halfFloat1;
276
277 return *this;
278 }
279 };
280
281 Color(uint16_t r, uint16_t g, uint16_t b)
282 : rgba(r, g, b) {
283 }
284
285 Color(int r, int g, int b)
286 : rgba((uint16_t) r, (uint16_t) g, (uint16_t) b) {
287 }
288
289 Color() {}
290
291 Color(const Color &other) {
292 this->rgba = other.rgba;
293 }
294
295 Color &operator=(const Color &other) {
296 this->rgba = other.rgba;
297
298 return *this;
299 }
300
301 RGBA rgba;
302 uint16_t channel[4];
303 };
304 static_assert(sizeof(Color) == 8, "BC6h::Color must be 8 bytes long");
305
306 inline int32_t extendSign(int32_t val, size_t size) {
307 // Suppose we have a 2-bit integer being stored in 4 bit variable:
308 // x = 0b00AB
309 //
310 // In order to sign extend x, we need to turn the 0s into A's:
311 // x_extend = 0bAAAB
312 //
313 // We can do that by flipping A in x then subtracting 0b0010 from x.
314 // Suppose A is 1:
315 // x = 0b001B
316 // x_flip = 0b000B
317 // x_minus = 0b111B
318 // Since A is flipped to 0, subtracting the mask sets it and all the bits above it to 1.
319 // And if A is 0:
320 // x = 0b000B
321 // x_flip = 0b001B
322 // x_minus = 0b000B
323 // We unset the bit we flipped, and touch no other bit
324 uint16_t mask = 1u << (size - 1);
325 return (val ^ mask) - mask;
326 }
327
328 static int constexpr RGBfChannels = 3;
329 struct RGBf {
330 uint16_t channel[RGBfChannels];
331 size_t size[RGBfChannels];
332 bool isSigned;
333
334 RGBf() {
335 static_assert(RGBfChannels == 3, "RGBf must have exactly 3 channels");
336 static_assert(sizeof(channel) / sizeof(channel[0]) == RGBfChannels, "RGBf must have exactly 3 channels");
337 static_assert(sizeof(channel) / sizeof(channel[0]) == sizeof(size) / sizeof(size[0]), "RGBf requires equally sized arrays for channels and channel sizes");
338
339 for (int i = 0; i < RGBfChannels; i++) {
340 channel[i] = 0;
341 size[i] = 0;
342 }
343
344 isSigned = false;
345 }
346
347 void extendSign() {
348 for (int i = 0; i < RGBfChannels; i++) {
349 channel[i] = BC6H::extendSign(channel[i], size[i]);
350 }
351 }
352
353 // Assuming this is the delta, take the base-endpoint and transform this into
354 // a proper endpoint.
355 //
356 // The final computed endpoint is truncated to the base-endpoint's size;
357 void resolveDelta(RGBf base) {
358 for (int i = 0; i < RGBfChannels; i++) {
359 size[i] = base.size[i];
360 channel[i] = (base.channel[i] + channel[i]) & ((1 << base.size[i]) - 1);
361 }
362
363 // Per the spec:
364 // "For signed formats, the results of the delta calculation must be sign
365 // extended as well."
366 if (isSigned) {
367 extendSign();
368 }
369 }
370
371 void unquantize() {
372 if (isSigned) {
373 unquantizeSigned();
374 } else {
375 unquantizeUnsigned();
376 }
377 }
378
379 void unquantizeUnsigned() {
380 for (int i = 0; i < RGBfChannels; i++) {
381 if (size[i] >= 15 || channel[i] == 0) {
382 continue;
383 } else if (channel[i] == ((1u << size[i]) - 1)) {
384 channel[i] = 0xFFFFu;
385 } else {
386 // Need 32 bits to avoid overflow
387 uint32_t tmp = channel[i];
388 channel[i] = (uint16_t) (((tmp << 16) + 0x8000) >> size[i]);
389 }
390 size[i] = 16;
391 }
392 }
393
394 void unquantizeSigned() {
395 for (int i = 0; i < RGBfChannels; i++) {
396 if (size[i] >= 16 || channel[i] == 0) {
397 continue;
398 }
399
400 int16_t value = (int16_t)channel[i];
401 int32_t result = value;
402 bool signBit = value < 0;
403 if (signBit) {
404 value = -value;
405 }
406
407 if (value >= ((1 << (size[i] - 1)) - 1)) {
408 result = 0x7FFF;
409 } else {
410 // Need 32 bits to avoid overflow
411 int32_t tmp = value;
412 result = (((tmp << 15) + 0x4000) >> (size[i] - 1));
413 }
414
415 if (signBit) {
416 result = -result;
417 }
418
419 channel[i] = (uint16_t) result;
420 size[i] = 16;
421 }
422 }
423 };
424
425 struct Data {
426 uint64_t low64;
427 uint64_t high64;
428
429 Data() = default;
430
431 Data(uint64_t low64, uint64_t high64)
432 : low64(low64), high64(high64) {
433 }
434
435 // Consumes the lowest N bits from from low64 and high64 where N is:
436 // abs(MSB - LSB)
437 // MSB and LSB come from the block description of the BC6h spec and specify
438 // the location of the bits in the returned bitstring.
439 //
440 // If MSB < LSB, then the bits are reversed. Otherwise, the bitstring is read and
441 // shifted without further modification.
442 //
443 uint32_t consumeBits(uint32_t MSB, uint32_t LSB) {
444 bool reversed = MSB < LSB;
445 if (reversed) {
446 std::swap(MSB, LSB);
447 }
448 assert(MSB - LSB + 1 < sizeof(uint32_t) * 8);
449
450 uint32_t numBits = MSB - LSB + 1;
451 uint32_t mask = (1 << numBits) - 1;
452 // Read the low N bits
453 uint32_t bits = (low64 & mask);
454
455 low64 >>= numBits;
456 // Put the low N bits of high64 into the high 64-N bits of low64
457 low64 |= (high64 & mask) << (sizeof(high64) * 8 - numBits);
458 high64 >>= numBits;
459
460 if (reversed) {
461 uint32_t tmp = 0;
462 for (uint32_t numSwaps = 0; numSwaps < numBits; numSwaps++) {
463 tmp <<= 1;
464 tmp |= (bits & 1);
465 bits >>= 1;
466 }
467
468 bits = tmp;
469 }
470
471 return bits << LSB;
472 }
473 };
474
475 struct IndexInfo {
476 uint64_t value;
477 int numBits;
478 };
479
480// Interpolates between two endpoints, then does a final unquantization step
481 Color interpolate(RGBf e0, RGBf e1, const IndexInfo &index, bool isSigned) {
482 static constexpr uint32_t weights3[] = {0, 9, 18, 27, 37, 46, 55, 64};
483 static constexpr uint32_t weights4[] = {0, 4, 9, 13, 17, 21, 26, 30,
484 34, 38, 43, 47, 51, 55, 60, 64};
485 static constexpr uint32_t const *weightsN[] = {
486 nullptr, nullptr, nullptr, weights3, weights4
487 };
488 auto weights = weightsN[index.numBits];
489 assert(weights != nullptr);
490 Color color;
491 uint32_t e0Weight = 64 - weights[index.value];
492 uint32_t e1Weight = weights[index.value];
493
494 for (int i = 0; i < RGBfChannels; i++) {
495 int32_t e0Channel = e0.channel[i];
496 int32_t e1Channel = e1.channel[i];
497
498 if (isSigned) {
499 e0Channel = extendSign(e0Channel, 16);
500 e1Channel = extendSign(e1Channel, 16);
501 }
502
503 int32_t e0Value = e0Channel * e0Weight;
504 int32_t e1Value = e1Channel * e1Weight;
505
506 uint32_t tmp = ((e0Value + e1Value + 32) >> 6);
507
508 // Need to unquantize value to limit it to the legal range of half-precision
509 // floats. We do this by scaling by 31/32 or 31/64 depending on if the value
510 // is signed or unsigned.
511 if (isSigned) {
512 tmp = ((tmp & 0x80000000) != 0) ? (((~tmp + 1) * 31) >> 5) | 0x8000 : (tmp * 31) >> 5;
513 // Don't return -0.0f, just normalize it to 0.0f.
514 if (tmp == 0x8000)
515 tmp = 0;
516 } else {
517 tmp = (tmp * 31) >> 6;
518 }
519
520 color.channel[i] = (uint16_t) tmp;
521 }
522
523 return color;
524 }
525
526 enum DataType {
527 // Endpoints
528 EP0 = 0,
529 EP1 = 1,
530 EP2 = 2,
531 EP3 = 3,
532 Mode,
533 Partition,
534 End,
535 };
536
537 enum Channel {
538 R = 0,
539 G = 1,
540 B = 2,
541 None,
542 };
543
544 struct DeltaBits {
545 size_t channel[3];
546
547 constexpr DeltaBits()
548 : channel{0, 0, 0} {
549 }
550
551 constexpr DeltaBits(size_t r, size_t g, size_t b)
552 : channel{r, g, b} {
553 }
554 };
555
556 struct ModeDesc {
557 int number;
558 bool hasDelta;
559 int partitionCount;
560 int endpointBits;
561 DeltaBits deltaBits;
562
563 constexpr ModeDesc()
564 : number(-1), hasDelta(false), partitionCount(0), endpointBits(0) {
565 }
566
567 constexpr ModeDesc(int number, bool hasDelta, int partitionCount, int endpointBits, DeltaBits deltaBits)
568 : number(number), hasDelta(hasDelta), partitionCount(partitionCount), endpointBits(endpointBits), deltaBits(deltaBits) {
569 }
570 };
571
572 struct BlockDesc {
573 DataType type;
574 Channel channel;
575 int MSB;
576 int LSB;
577 ModeDesc modeDesc;
578
579 constexpr BlockDesc()
580 : type(End), channel(None), MSB(0), LSB(0), modeDesc() {
581 }
582
583 constexpr BlockDesc(const DataType type, Channel channel, int MSB, int LSB, ModeDesc modeDesc)
584 : type(type), channel(channel), MSB(MSB), LSB(LSB), modeDesc(modeDesc) {
585 }
586
587 constexpr BlockDesc(DataType type, Channel channel, int MSB, int LSB)
588 : type(type), channel(channel), MSB(MSB), LSB(LSB), modeDesc() {
589 }
590 };
591
592// Turns a legal mode into an index into the BlockDesc table.
593// Illegal or reserved modes return -1.
594 static int modeToIndex(uint8_t mode) {
595 if (mode <= 3) {
596 return mode;
597 } else if ((mode & 0x2) != 0) {
598 if (mode <= 18) {
599// Turns 6 into 4, 7 into 5, 10 into 6, etc.
600 return (mode / 2) + 1 + (mode & 0x1);
601 } else if (mode == 22 || mode == 26 || mode == 30) {
602// Turns 22 into 11, 26 into 12, etc.
603 return mode / 4 + 6;
604 }
605 }
606
607 return -1;
608 }
609
610// Returns a description of the bitfields for each mode from the LSB
611// to the MSB before the index data starts.
612//
613// The numbers come from the BC6h block description. Each BlockDesc in the
614// {Type, Channel, MSB, LSB}
615// * Type describes which endpoint this is, or if this is a mode, a partition
616// number, or the end of the block description.
617// * Channel describes one of the 3 color channels within an endpoint
618// * MSB and LSB specificy:
619// * The size of the bitfield being read
620// * The position of the bitfield within the variable it is being read to
621// * If the bitfield is stored in reverse bit order
622// If MSB < LSB then the bitfield is stored in reverse order. The size of
623// the bitfield is abs(MSB-LSB+1). And the position of the bitfield within
624// the variable is min(LSB, MSB).
625//
626// Invalid or reserved modes return an empty list.
627 static constexpr int NumBlocks = 14;
628// The largest number of descriptions within a block.
629 static constexpr int MaxBlockDescIndex = 26;
630 static constexpr BlockDesc blockDescs[NumBlocks][MaxBlockDescIndex] = {
631// @fmt:off
632// Mode 0, Index 0
633{
634{ Mode, None, 1, 0, { 0, true, 2, 10, { 5, 5, 5 } } },
635{ EP2, G, 4, 4 }, { EP2, B, 4, 4 }, { EP3, B, 4, 4 },
636{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
637{ EP1, R, 4, 0 }, { EP3, G, 4, 4 }, { EP2, G, 3, 0 },
638{ EP1, G, 4, 0 }, { EP3, B, 0, 0 }, { EP3, G, 3, 0 },
639{ EP1, B, 4, 0 }, { EP3, B, 1, 1 }, { EP2, B, 3, 0 },
640{ EP2, R, 4, 0 }, { EP3, B, 2, 2 }, { EP3, R, 4, 0 },
641{ EP3, B, 3, 3 },
642{ Partition, None, 4, 0 },
643{ End, None, 0, 0},
644},
645// Mode 1, Index 1
646{
647{ Mode, None, 1, 0, { 1, true, 2, 7, { 6, 6, 6 } } },
648{ EP2, G, 5, 5 }, { EP3, G, 5, 4 }, { EP0, R, 6, 0 },
649{ EP3, B, 1, 0 }, { EP2, B, 4, 4 }, { EP0, G, 6, 0 },
650{ EP2, B, 5, 5 }, { EP3, B, 2, 2 }, { EP2, G, 4, 4 },
651{ EP0, B, 6, 0 }, { EP3, B, 3, 3 }, { EP3, B, 5, 5 },
652{ EP3, B, 4, 4 }, { EP1, R, 5, 0 }, { EP2, G, 3, 0 },
653{ EP1, G, 5, 0 }, { EP3, G, 3, 0 }, { EP1, B, 5, 0 },
654{ EP2, B, 3, 0 }, { EP2, R, 5, 0 }, { EP3, R, 5, 0 },
655{ Partition, None, 4, 0 },
656{ End, None, 0, 0},
657},
658// Mode 2, Index 2
659{
660{ Mode, None, 4, 0, { 2, true, 2, 11, { 5, 4, 4 } } },
661{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
662{ EP1, R, 4, 0 }, { EP0, R, 10, 10 }, { EP2, G, 3, 0 },
663{ EP1, G, 3, 0 }, { EP0, G, 10, 10 }, { EP3, B, 0, 0 },
664{ EP3, G, 3, 0 }, { EP1, B, 3, 0 }, { EP0, B, 10, 10 },
665{ EP3, B, 1, 1 }, { EP2, B, 3, 0 }, { EP2, R, 4, 0 },
666{ EP3, B, 2, 2 }, { EP3, R, 4, 0 }, { EP3, B, 3, 3 },
667{ Partition, None, 4, 0 },
668{ End, None, 0, 0},
669},
670// Mode 3, Index 3
671{
672{ Mode, None, 4, 0, { 3, false, 1, 10, { 0, 0, 0 } } },
673{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
674{ EP1, R, 9, 0 }, { EP1, G, 9, 0 }, { EP1, B, 9, 0 },
675{ End, None, 0, 0},
676},
677// Mode 6, Index 4
678{
679{ Mode, None, 4, 0, { 6, true, 2, 11, { 4, 5, 4 } } }, // 1 1
680{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
681{ EP1, R, 3, 0 }, { EP0, R, 10, 10 }, { EP3, G, 4, 4 },
682{ EP2, G, 3, 0 }, { EP1, G, 4, 0 }, { EP0, G, 10, 10 },
683{ EP3, G, 3, 0 }, { EP1, B, 3, 0 }, { EP0, B, 10, 10 },
684{ EP3, B, 1, 1 }, { EP2, B, 3, 0 }, { EP2, R, 3, 0 },
685{ EP3, B, 0, 0 }, { EP3, B, 2, 2 }, { EP3, R, 3, 0 }, // 18 19
686{ EP2, G, 4, 4 }, { EP3, B, 3, 3 }, // 2 21
687{ Partition, None, 4, 0 },
688{ End, None, 0, 0},
689},
690// Mode 7, Index 5
691{
692{ Mode, None, 4, 0, { 7, true, 1, 11, { 9, 9, 9 } } },
693{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
694{ EP1, R, 8, 0 }, { EP0, R, 10, 10 }, { EP1, G, 8, 0 },
695{ EP0, G, 10, 10 }, { EP1, B, 8, 0 }, { EP0, B, 10, 10 },
696{ End, None, 0, 0},
697},
698// Mode 10, Index 6
699{
700{ Mode, None, 4, 0, { 10, true, 2, 11, { 4, 4, 5 } } },
701{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
702{ EP1, R, 3, 0 }, { EP0, R, 10, 10 }, { EP2, B, 4, 4 },
703{ EP2, G, 3, 0 }, { EP1, G, 3, 0 }, { EP0, G, 10, 10 },
704{ EP3, B, 0, 0 }, { EP3, G, 3, 0 }, { EP1, B, 4, 0 },
705{ EP0, B, 10, 10 }, { EP2, B, 3, 0 }, { EP2, R, 3, 0 },
706{ EP3, B, 1, 1 }, { EP3, B, 2, 2 }, { EP3, R, 3, 0 },
707{ EP3, B, 4, 4 }, { EP3, B, 3, 3 },
708{ Partition, None, 4, 0 },
709{ End, None, 0, 0},
710},
711// Mode 11, Index 7
712{
713{ Mode, None, 4, 0, { 11, true, 1, 12, { 8, 8, 8 } } },
714{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
715{ EP1, R, 7, 0 }, { EP0, R, 10, 11 }, { EP1, G, 7, 0 },
716{ EP0, G, 10, 11 }, { EP1, B, 7, 0 }, { EP0, B, 10, 11 },
717{ End, None, 0, 0},
718},
719// Mode 14, Index 8
720{
721{ Mode, None, 4, 0, { 14, true, 2, 9, { 5, 5, 5 } } },
722{ EP0, R, 8, 0 }, { EP2, B, 4, 4 }, { EP0, G, 8, 0 },
723{ EP2, G, 4, 4 }, { EP0, B, 8, 0 }, { EP3, B, 4, 4 },
724{ EP1, R, 4, 0 }, { EP3, G, 4, 4 }, { EP2, G, 3, 0 },
725{ EP1, G, 4, 0 }, { EP3, B, 0, 0 }, { EP3, G, 3, 0 },
726{ EP1, B, 4, 0 }, { EP3, B, 1, 1 }, { EP2, B, 3, 0 },
727{ EP2, R, 4, 0 }, { EP3, B, 2, 2 }, { EP3, R, 4, 0 },
728{ EP3, B, 3, 3 },
729{ Partition, None, 4, 0 },
730{ End, None, 0, 0},
731},
732// Mode 15, Index 9
733{
734{ Mode, None, 4, 0, { 15, true, 1, 16, { 4, 4, 4 } } },
735{ EP0, R, 9, 0 }, { EP0, G, 9, 0 }, { EP0, B, 9, 0 },
736{ EP1, R, 3, 0 }, { EP0, R, 10, 15 }, { EP1, G, 3, 0 },
737{ EP0, G, 10, 15 }, { EP1, B, 3, 0 }, { EP0, B, 10, 15 },
738{ End, None, 0, 0},
739},
740// Mode 18, Index 10
741{
742{ Mode, None, 4, 0, { 18, true, 2, 8, { 6, 5, 5 } } },
743{ EP0, R, 7, 0 }, { EP3, G, 4, 4 }, { EP2, B, 4, 4 },
744{ EP0, G, 7, 0 }, { EP3, B, 2, 2 }, { EP2, G, 4, 4 },
745{ EP0, B, 7, 0 }, { EP3, B, 3, 3 }, { EP3, B, 4, 4 },
746{ EP1, R, 5, 0 }, { EP2, G, 3, 0 }, { EP1, G, 4, 0 },
747{ EP3, B, 0, 0 }, { EP3, G, 3, 0 }, { EP1, B, 4, 0 },
748{ EP3, B, 1, 1 }, { EP2, B, 3, 0 }, { EP2, R, 5, 0 },
749{ EP3, R, 5, 0 },
750{ Partition, None, 4, 0 },
751{ End, None, 0, 0},
752},
753// Mode 22, Index 11
754{
755{ Mode, None, 4, 0, { 22, true, 2, 8, { 5, 6, 5 } } },
756{ EP0, R, 7, 0 }, { EP3, B, 0, 0 }, { EP2, B, 4, 4 },
757{ EP0, G, 7, 0 }, { EP2, G, 5, 5 }, { EP2, G, 4, 4 },
758{ EP0, B, 7, 0 }, { EP3, G, 5, 5 }, { EP3, B, 4, 4 },
759{ EP1, R, 4, 0 }, { EP3, G, 4, 4 }, { EP2, G, 3, 0 },
760{ EP1, G, 5, 0 }, { EP3, G, 3, 0 }, { EP1, B, 4, 0 },
761{ EP3, B, 1, 1 }, { EP2, B, 3, 0 }, { EP2, R, 4, 0 },
762{ EP3, B, 2, 2 }, { EP3, R, 4, 0 }, { EP3, B, 3, 3 },
763{ Partition, None, 4, 0 },
764{ End, None, 0, 0},
765},
766// Mode 26, Index 12
767{
768{ Mode, None, 4, 0, { 26, true, 2, 8, { 5, 5, 6 } } },
769{ EP0, R, 7, 0 }, { EP3, B, 1, 1 }, { EP2, B, 4, 4 },
770{ EP0, G, 7, 0 }, { EP2, B, 5, 5 }, { EP2, G, 4, 4 },
771{ EP0, B, 7, 0 }, { EP3, B, 5, 5 }, { EP3, B, 4, 4 },
772{ EP1, R, 4, 0 }, { EP3, G, 4, 4 }, { EP2, G, 3, 0 },
773{ EP1, G, 4, 0 }, { EP3, B, 0, 0 }, { EP3, G, 3, 0 },
774{ EP1, B, 5, 0 }, { EP2, B, 3, 0 }, { EP2, R, 4, 0 },
775{ EP3, B, 2, 2 }, { EP3, R, 4, 0 }, { EP3, B, 3, 3 },
776{ Partition, None, 4, 0 },
777{ End, None, 0, 0},
778},
779// Mode 30, Index 13
780{
781{ Mode, None, 4, 0, { 30, false, 2, 6, { 0, 0, 0 } } },
782{ EP0, R, 5, 0 }, { EP3, G, 4, 4 }, { EP3, B, 0, 0 },
783{ EP3, B, 1, 1 }, { EP2, B, 4, 4 }, { EP0, G, 5, 0 },
784{ EP2, G, 5, 5 }, { EP2, B, 5, 5 }, { EP3, B, 2, 2 },
785{ EP2, G, 4, 4 }, { EP0, B, 5, 0 }, { EP3, G, 5, 5 },
786{ EP3, B, 3, 3 }, { EP3, B, 5, 5 }, { EP3, B, 4, 4 },
787{ EP1, R, 5, 0 }, { EP2, G, 3, 0 }, { EP1, G, 5, 0 },
788{ EP3, G, 3, 0 }, { EP1, B, 5, 0 }, { EP2, B, 3, 0 },
789{ EP2, R, 5, 0 }, { EP3, R, 5, 0 },
790{ Partition, None, 4, 0 },
791{ End, None, 0, 0},
792}
793// @fmt:on
794 };
795
796 struct Block {
797 uint64_t low64;
798 uint64_t high64;
799
800 void decode(uint8_t *dst, size_t dstX, size_t dstY, size_t dstWidth, size_t dstHeight, size_t dstPitch, size_t dstBpp, bool isSigned) const {
801 uint8_t mode = 0;
802 Data data(low64, high64);
803 assert(dstBpp == sizeof(Color));
804
805 if ((data.low64 & 0x2) == 0) {
806 mode = data.consumeBits(1, 0);
807 } else {
808 mode = data.consumeBits(4, 0);
809 }
810
811 int blockIndex = modeToIndex(mode);
812 // Handle illegal or reserved mode
813 if (blockIndex == -1) {
814 for (int y = 0; y < 4 && y + dstY < dstHeight; y++) {
815 for (int x = 0; x < 4 && x + dstX < dstWidth; x++) {
816 auto out = reinterpret_cast<Color *>(dst + sizeof(Color) * x + dstPitch * y);
817 out->rgba = {0, 0, 0};
818 }
819 }
820 return;
821 }
822 const BlockDesc *blockDesc = blockDescs[blockIndex];
823
824 RGBf e[4];
825 e[0].isSigned = e[1].isSigned = e[2].isSigned = e[3].isSigned = isSigned;
826
827 int partition = 0;
828 ModeDesc modeDesc;
829 for (int index = 0; blockDesc[index].type != End; index++) {
830 const BlockDesc desc = blockDesc[index];
831
832 switch (desc.type) {
833 case Mode:
834 modeDesc = desc.modeDesc;
835 assert(modeDesc.number == mode);
836
837 e[0].size[0] = e[0].size[1] = e[0].size[2] = modeDesc.endpointBits;
838 for (int i = 0; i < RGBfChannels; i++) {
839 if (modeDesc.hasDelta) {
840 e[1].size[i] = e[2].size[i] = e[3].size[i] = modeDesc.deltaBits.channel[i];
841 } else {
842 e[1].size[i] = e[2].size[i] = e[3].size[i] = modeDesc.endpointBits;
843 }
844 }
845 break;
846 case Partition:
847 partition |= data.consumeBits(desc.MSB, desc.LSB);
848 break;
849 case EP0:
850 case EP1:
851 case EP2:
852 case EP3:
853 e[desc.type].channel[desc.channel] |= data.consumeBits(desc.MSB, desc.LSB);
854 break;
855 default:
856 assert(false);
857 return;
858 }
859 }
860
861 // Sign extension
862 if (isSigned) {
863 for (int ep = 0; ep < modeDesc.partitionCount * 2; ep++) {
864 e[ep].extendSign();
865 }
866 } else if (modeDesc.hasDelta) {
867 // Don't sign-extend the base endpoint in an unsigned format.
868 for (int ep = 1; ep < modeDesc.partitionCount * 2; ep++) {
869 e[ep].extendSign();
870 }
871 }
872
873 // Turn the deltas into endpoints
874 if (modeDesc.hasDelta) {
875 for (int ep = 1; ep < modeDesc.partitionCount * 2; ep++) {
876 e[ep].resolveDelta(e[0]);
877 }
878 }
879
880 for (int ep = 0; ep < modeDesc.partitionCount * 2; ep++) {
881 e[ep].unquantize();
882 }
883
884 // Get the indices, calculate final colors, and output
885 for (int y = 0; y < 4; y++) {
886 for (int x = 0; x < 4; x++) {
887 int pixelNum = x + y * 4;
888 IndexInfo idx;
889 bool isAnchor = false;
890 int firstEndpoint = 0;
891 // Bc6H can have either 1 or 2 petitions depending on the mode.
892 // The number of petitions affects the number of indices with implicit
893 // leading 0 bits and the number of bits per index.
894 if (modeDesc.partitionCount == 1) {
895 idx.numBits = 4;
896 // There's an implicit leading 0 bit for the first idx
897 isAnchor = (pixelNum == 0);
898 } else {
899 idx.numBits = 3;
900 // There are 2 indices with implicit leading 0-bits.
901 isAnchor = ((pixelNum == 0) || (pixelNum == AnchorTable2[partition]));
902 firstEndpoint = PartitionTable2[partition][pixelNum] * 2;
903 }
904
905 idx.value = data.consumeBits(idx.numBits - isAnchor - 1, 0);
906
907 // Don't exit the loop early, we need to consume these index bits regardless if
908 // we actually output them or not.
909 if ((y + dstY >= dstHeight) || (x + dstX >= dstWidth)) {
910 continue;
911 }
912
913 Color color = interpolate(e[firstEndpoint], e[firstEndpoint + 1], idx, isSigned);
914 auto out = reinterpret_cast<Color *>(dst + dstBpp * x + dstPitch * y);
915 *out = color;
916 }
917 }
918 }
919 };
920
921 } // namespace BC6H
922
923 namespace BC7 {
924// https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_texture_compression_bptc.txt
925// https://docs.microsoft.com/en-us/windows/win32/direct3d11/bc7-format
926
927 struct Bitfield {
928 int offset;
929 int count;
930
931 constexpr Bitfield Then(const int bits) { return {offset + count, bits}; }
932
933 constexpr bool operator==(const Bitfield &rhs) {
934 return offset == rhs.offset && count == rhs.count;
935 }
936 };
937
938 struct Mode {
939 const int IDX; // Mode index
940 const int NS; // Number of subsets in each partition
941 const int PB; // Partition bits
942 const int RB; // Rotation bits
943 const int ISB; // Index selection bits
944 const int CB; // Color bits
945 const int AB; // Alpha bits
946 const int EPB; // Endpoint P-bits
947 const int SPB; // Shared P-bits
948 const int IB; // Primary index bits per element
949 const int IBC; // Primary index bits total
950 const int IB2; // Secondary index bits per element
951
952 constexpr int NumColors() const { return NS * 2; }
953
954 constexpr Bitfield Partition() const { return {IDX + 1, PB}; }
955
956 constexpr Bitfield Rotation() const { return Partition().Then(RB); }
957
958 constexpr Bitfield IndexSelection() const { return Rotation().Then(ISB); }
959
960 constexpr Bitfield Red(int idx) const {
961 return IndexSelection().Then(CB * idx).Then(CB);
962 }
963
964 constexpr Bitfield Green(int idx) const {
965 return Red(NumColors() - 1).Then(CB * idx).Then(CB);
966 }
967
968 constexpr Bitfield Blue(int idx) const {
969 return Green(NumColors() - 1).Then(CB * idx).Then(CB);
970 }
971
972 constexpr Bitfield Alpha(int idx) const {
973 return Blue(NumColors() - 1).Then(AB * idx).Then(AB);
974 }
975
976 constexpr Bitfield EndpointPBit(int idx) const {
977 return Alpha(NumColors() - 1).Then(EPB * idx).Then(EPB);
978 }
979
980 constexpr Bitfield SharedPBit0() const {
981 return EndpointPBit(NumColors() - 1).Then(SPB);
982 }
983
984 constexpr Bitfield SharedPBit1() const {
985 return SharedPBit0().Then(SPB);
986 }
987
988 constexpr Bitfield PrimaryIndex(int offset, int count) const {
989 return SharedPBit1().Then(offset).Then(count);
990 }
991
992 constexpr Bitfield SecondaryIndex(int offset, int count) const {
993 return SharedPBit1().Then(IBC + offset).Then(count);
994 }
995 };
996
997 static constexpr Mode Modes[] = {
998 // IDX NS PB RB ISB CB AB EPB SPB IB IBC, IB2
999 /**/ {0x0, 0x3, 0x4, 0x0, 0x0, 0x4, 0x0, 0x1, 0x0, 0x3, 0x2d, 0x0},
1000/**/ {0x1, 0x2, 0x6, 0x0, 0x0, 0x6, 0x0, 0x0, 0x1, 0x3, 0x2e, 0x0},
1001/**/ {0x2, 0x3, 0x6, 0x0, 0x0, 0x5, 0x0, 0x0, 0x0, 0x2, 0x1d, 0x0},
1002/**/ {0x3, 0x2, 0x6, 0x0, 0x0, 0x7, 0x0, 0x1, 0x0, 0x2, 0x1e, 0x0},
1003/**/ {0x4, 0x1, 0x0, 0x2, 0x1, 0x5, 0x6, 0x0, 0x0, 0x2, 0x1f, 0x3},
1004/**/ {0x5, 0x1, 0x0, 0x2, 0x0, 0x7, 0x8, 0x0, 0x0, 0x2, 0x1f, 0x2},
1005/**/ {0x6, 0x1, 0x0, 0x0, 0x0, 0x7, 0x7, 0x1, 0x0, 0x4, 0x3f, 0x0},
1006/**/ {0x7, 0x2, 0x6, 0x0, 0x0, 0x5, 0x5, 0x1, 0x0, 0x2, 0x1e, 0x0},
1007/**/ {-1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x00, 0x0},
1008 };
1009
1010 static constexpr int MaxPartitions = 64;
1011 static constexpr int MaxSubsets = 3;
1012
1013 static constexpr uint8_t PartitionTable2[MaxPartitions][16] = {
1014 {0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1},
1015 {0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1},
1016 {0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1},
1017 {0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1},
1018 {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1},
1019 {0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1},
1020 {0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1},
1021 {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1},
1022 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1},
1023 {0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
1024 {0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1},
1025 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1},
1026 {0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
1027 {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1},
1028 {0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
1029 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1},
1030 {0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1},
1031 {0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0},
1032 {0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0},
1033 {0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0},
1034 {0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0},
1035 {0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0},
1036 {0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0},
1037 {0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1},
1038 {0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0},
1039 {0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0},
1040 {0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0},
1041 {0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0},
1042 {0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0},
1043 {0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0},
1044 {0, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0},
1045 {0, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0},
1046 {0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1},
1047 {0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1},
1048 {0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0},
1049 {0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0},
1050 {0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0},
1051 {0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0},
1052 {0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1},
1053 {0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1},
1054 {0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0},
1055 {0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0},
1056 {0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0},
1057 {0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 0},
1058 {0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0},
1059 {0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1},
1060 {0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1},
1061 {0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0},
1062 {0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0},
1063 {0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0},
1064 {0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0},
1065 {0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0},
1066 {0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1},
1067 {0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1},
1068 {0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0},
1069 {0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 0},
1070 {0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1},
1071 {0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1},
1072 {0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1},
1073 {0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1},
1074 {0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1},
1075 {0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0},
1076 {0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0},
1077 {0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1},
1078 };
1079
1080 static constexpr uint8_t PartitionTable3[MaxPartitions][16] = {
1081 {0, 0, 1, 1, 0, 0, 1, 1, 0, 2, 2, 1, 2, 2, 2, 2},
1082 {0, 0, 0, 1, 0, 0, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1},
1083 {0, 0, 0, 0, 2, 0, 0, 1, 2, 2, 1, 1, 2, 2, 1, 1},
1084 {0, 2, 2, 2, 0, 0, 2, 2, 0, 0, 1, 1, 0, 1, 1, 1},
1085 {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 1, 1, 2, 2},
1086 {0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 2, 2, 0, 0, 2, 2},
1087 {0, 0, 2, 2, 0, 0, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1},
1088 {0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1},
1089 {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2},
1090 {0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2},
1091 {0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2},
1092 {0, 0, 1, 2, 0, 0, 1, 2, 0, 0, 1, 2, 0, 0, 1, 2},
1093 {0, 1, 1, 2, 0, 1, 1, 2, 0, 1, 1, 2, 0, 1, 1, 2},
1094 {0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 2},
1095 {0, 0, 1, 1, 0, 1, 1, 2, 1, 1, 2, 2, 1, 2, 2, 2},
1096 {0, 0, 1, 1, 2, 0, 0, 1, 2, 2, 0, 0, 2, 2, 2, 0},
1097 {0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 2, 1, 1, 2, 2},
1098 {0, 1, 1, 1, 0, 0, 1, 1, 2, 0, 0, 1, 2, 2, 0, 0},
1099 {0, 0, 0, 0, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2},
1100 {0, 0, 2, 2, 0, 0, 2, 2, 0, 0, 2, 2, 1, 1, 1, 1},
1101 {0, 1, 1, 1, 0, 1, 1, 1, 0, 2, 2, 2, 0, 2, 2, 2},
1102 {0, 0, 0, 1, 0, 0, 0, 1, 2, 2, 2, 1, 2, 2, 2, 1},
1103 {0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 2, 2, 0, 1, 2, 2},
1104 {0, 0, 0, 0, 1, 1, 0, 0, 2, 2, 1, 0, 2, 2, 1, 0},
1105 {0, 1, 2, 2, 0, 1, 2, 2, 0, 0, 1, 1, 0, 0, 0, 0},
1106 {0, 0, 1, 2, 0, 0, 1, 2, 1, 1, 2, 2, 2, 2, 2, 2},
1107 {0, 1, 1, 0, 1, 2, 2, 1, 1, 2, 2, 1, 0, 1, 1, 0},
1108 {0, 0, 0, 0, 0, 1, 1, 0, 1, 2, 2, 1, 1, 2, 2, 1},
1109 {0, 0, 2, 2, 1, 1, 0, 2, 1, 1, 0, 2, 0, 0, 2, 2},
1110 {0, 1, 1, 0, 0, 1, 1, 0, 2, 0, 0, 2, 2, 2, 2, 2},
1111 {0, 0, 1, 1, 0, 1, 2, 2, 0, 1, 2, 2, 0, 0, 1, 1},
1112 {0, 0, 0, 0, 2, 0, 0, 0, 2, 2, 1, 1, 2, 2, 2, 1},
1113 {0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 2, 2, 1, 2, 2, 2},
1114 {0, 2, 2, 2, 0, 0, 2, 2, 0, 0, 1, 2, 0, 0, 1, 1},
1115 {0, 0, 1, 1, 0, 0, 1, 2, 0, 0, 2, 2, 0, 2, 2, 2},
1116 {0, 1, 2, 0, 0, 1, 2, 0, 0, 1, 2, 0, 0, 1, 2, 0},
1117 {0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 0, 0, 0, 0},
1118 {0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0},
1119 {0, 1, 2, 0, 2, 0, 1, 2, 1, 2, 0, 1, 0, 1, 2, 0},
1120 {0, 0, 1, 1, 2, 2, 0, 0, 1, 1, 2, 2, 0, 0, 1, 1},
1121 {0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 0, 0, 0, 0, 1, 1},
1122 {0, 1, 0, 1, 0, 1, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2},
1123 {0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 2, 1, 2, 1, 2, 1},
1124 {0, 0, 2, 2, 1, 1, 2, 2, 0, 0, 2, 2, 1, 1, 2, 2},
1125 {0, 0, 2, 2, 0, 0, 1, 1, 0, 0, 2, 2, 0, 0, 1, 1},
1126 {0, 2, 2, 0, 1, 2, 2, 1, 0, 2, 2, 0, 1, 2, 2, 1},
1127 {0, 1, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 0, 1, 0, 1},
1128 {0, 0, 0, 0, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1},
1129 {0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 2, 2, 2, 2},
1130 {0, 2, 2, 2, 0, 1, 1, 1, 0, 2, 2, 2, 0, 1, 1, 1},
1131 {0, 0, 0, 2, 1, 1, 1, 2, 0, 0, 0, 2, 1, 1, 1, 2},
1132 {0, 0, 0, 0, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2},
1133 {0, 2, 2, 2, 0, 1, 1, 1, 0, 1, 1, 1, 0, 2, 2, 2},
1134 {0, 0, 0, 2, 1, 1, 1, 2, 1, 1, 1, 2, 0, 0, 0, 2},
1135 {0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 2, 2, 2, 2},
1136 {0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 2, 2, 1, 1, 2},
1137 {0, 1, 1, 0, 0, 1, 1, 0, 2, 2, 2, 2, 2, 2, 2, 2},
1138 {0, 0, 2, 2, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 2, 2},
1139 {0, 0, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 0, 0, 2, 2},
1140 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 2},
1141 {0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1},
1142 {0, 2, 2, 2, 1, 2, 2, 2, 0, 2, 2, 2, 1, 2, 2, 2},
1143 {0, 1, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2},
1144 {0, 1, 1, 1, 2, 0, 1, 1, 2, 2, 0, 1, 2, 2, 2, 0},
1145 };
1146
1147 static constexpr uint8_t AnchorTable2[MaxPartitions] = {
1148// @fmt:off
11490xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf,
11500xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf,
11510xf, 0x2, 0x8, 0x2, 0x2, 0x8, 0x8, 0xf,
11520x2, 0x8, 0x2, 0x2, 0x8, 0x8, 0x2, 0x2,
11530xf, 0xf, 0x6, 0x8, 0x2, 0x8, 0xf, 0xf,
11540x2, 0x8, 0x2, 0x2, 0x2, 0xf, 0xf, 0x6,
11550x6, 0x2, 0x6, 0x8, 0xf, 0xf, 0x2, 0x2,
11560xf, 0xf, 0xf, 0xf, 0xf, 0x2, 0x2, 0xf,
1157// @fmt:on
1158 };
1159
1160 static constexpr uint8_t AnchorTable3a[MaxPartitions] = {
1161// @fmt:off
11620x3, 0x3, 0xf, 0xf, 0x8, 0x3, 0xf, 0xf,
11630x8, 0x8, 0x6, 0x6, 0x6, 0x5, 0x3, 0x3,
11640x3, 0x3, 0x8, 0xf, 0x3, 0x3, 0x6, 0xa,
11650x5, 0x8, 0x8, 0x6, 0x8, 0x5, 0xf, 0xf,
11660x8, 0xf, 0x3, 0x5, 0x6, 0xa, 0x8, 0xf,
11670xf, 0x3, 0xf, 0x5, 0xf, 0xf, 0xf, 0xf,
11680x3, 0xf, 0x5, 0x5, 0x5, 0x8, 0x5, 0xa,
11690x5, 0xa, 0x8, 0xd, 0xf, 0xc, 0x3, 0x3,
1170// @fmt:on
1171 };
1172
1173 static constexpr uint8_t AnchorTable3b[MaxPartitions] = {
1174// @fmt:off
11750xf, 0x8, 0x8, 0x3, 0xf, 0xf, 0x3, 0x8,
11760xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0x8,
11770xf, 0x8, 0xf, 0x3, 0xf, 0x8, 0xf, 0x8,
11780x3, 0xf, 0x6, 0xa, 0xf, 0xf, 0xa, 0x8,
11790xf, 0x3, 0xf, 0xa, 0xa, 0x8, 0x9, 0xa,
11800x6, 0xf, 0x8, 0xf, 0x3, 0x6, 0x6, 0x8,
11810xf, 0x3, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf,
11820xf, 0xf, 0xf, 0xf, 0x3, 0xf, 0xf, 0x8,
1183// @fmt:on
1184 };
1185
1186 struct Color {
1187 struct RGB {
1188 RGB() = default;
1189
1190 RGB(uint8_t r, uint8_t g, uint8_t b)
1191 : b(b), g(g), r(r) {}
1192
1193 RGB(int r, int g, int b)
1194 : b(static_cast<uint8_t>(b)), g(static_cast<uint8_t>(g)), r(static_cast<uint8_t>(r)) {}
1195
1196 RGB operator<<(int shift) const { return {r << shift, g << shift, b << shift}; }
1197
1198 RGB operator>>(int shift) const { return {r >> shift, g >> shift, b >> shift}; }
1199
1200 RGB operator|(int bits) const { return {r | bits, g | bits, b | bits}; }
1201
1202 RGB operator|(const RGB &rhs) const { return {r | rhs.r, g | rhs.g, b | rhs.b}; }
1203
1204 RGB operator+(const RGB &rhs) const { return {r + rhs.r, g + rhs.g, b + rhs.b}; }
1205
1206 uint8_t b;
1207 uint8_t g;
1208 uint8_t r;
1209 };
1210
1211 RGB rgb;
1212 uint8_t a;
1213 };
1214
1215 static_assert(sizeof(Color) == 4, "Color size must be 4 bytes");
1216
1217 struct Block {
1218 constexpr uint64_t Get(const Bitfield &bf) const {
1219 uint64_t mask = (1ULL << bf.count) - 1;
1220 if (bf.offset + bf.count <= 64) {
1221 return (low >> bf.offset) & mask;
1222 }
1223 if (bf.offset >= 64) {
1224 return (high >> (bf.offset - 64)) & mask;
1225 }
1226 return ((low >> bf.offset) | (high << (64 - bf.offset))) & mask;
1227 }
1228
1229 const Mode &mode() const {
1230 if ((low & 0b00000001) != 0) {
1231 return Modes[0];
1232 }
1233 if ((low & 0b00000010) != 0) {
1234 return Modes[1];
1235 }
1236 if ((low & 0b00000100) != 0) {
1237 return Modes[2];
1238 }
1239 if ((low & 0b00001000) != 0) {
1240 return Modes[3];
1241 }
1242 if ((low & 0b00010000) != 0) {
1243 return Modes[4];
1244 }
1245 if ((low & 0b00100000) != 0) {
1246 return Modes[5];
1247 }
1248 if ((low & 0b01000000) != 0) {
1249 return Modes[6];
1250 }
1251 if ((low & 0b10000000) != 0) {
1252 return Modes[7];
1253 }
1254 return Modes[8]; // Invalid mode
1255 }
1256
1257 struct IndexInfo {
1258 uint64_t value;
1259 int numBits;
1260 };
1261
1262 uint8_t interpolate(uint8_t e0, uint8_t e1, const IndexInfo &index) const {
1263 static constexpr uint16_t weights2[] = {0, 21, 43, 64};
1264 static constexpr uint16_t weights3[] = {0, 9, 18, 27, 37, 46, 55, 64};
1265 static constexpr uint16_t weights4[] = {0, 4, 9, 13, 17, 21, 26, 30,
1266 34, 38, 43, 47, 51, 55, 60, 64};
1267 static constexpr uint16_t const *weightsN[] = {
1268 nullptr, nullptr, weights2, weights3, weights4
1269 };
1270 auto weights = weightsN[index.numBits];
1271 assert(weights != nullptr);
1272 return (uint8_t) (((64 - weights[index.value]) * uint16_t(e0) + weights[index.value] * uint16_t(e1) + 32) >> 6);
1273 }
1274
1275 void decode(uint8_t *dst, size_t dstX, size_t dstY, size_t dstWidth, size_t dstHeight, size_t dstPitch) const {
1276 auto const &mode = this->mode();
1277
1278 if (mode.IDX < 0) // Invalid mode:
1279 {
1280 for (size_t y = 0; y < 4 && y + dstY < dstHeight; y++) {
1281 for (size_t x = 0; x < 4 && x + dstX < dstWidth; x++) {
1282 auto out = reinterpret_cast<Color *>(dst + sizeof(Color) * x + dstPitch * y);
1283 out->rgb = {0, 0, 0};
1284 out->a = 0;
1285 }
1286 }
1287 return;
1288 }
1289
1290 using Endpoint = std::array<Color, 2>;
1291 std::array<Endpoint, MaxSubsets> subsets;
1292
1293 for (size_t i = 0; i < mode.NS; i++) {
1294 auto &subset = subsets[i];
1295 subset[0].rgb.r = Get(mode.Red(i * 2 + 0));
1296 subset[0].rgb.g = Get(mode.Green(i * 2 + 0));
1297 subset[0].rgb.b = Get(mode.Blue(i * 2 + 0));
1298 subset[0].a = (mode.AB > 0) ? Get(mode.Alpha(i * 2 + 0)) : 255;
1299
1300 subset[1].rgb.r = Get(mode.Red(i * 2 + 1));
1301 subset[1].rgb.g = Get(mode.Green(i * 2 + 1));
1302 subset[1].rgb.b = Get(mode.Blue(i * 2 + 1));
1303 subset[1].a = (mode.AB > 0) ? Get(mode.Alpha(i * 2 + 1)) : 255;
1304 }
1305
1306 if (mode.SPB > 0) {
1307 auto pbit0 = Get(mode.SharedPBit0());
1308 auto pbit1 = Get(mode.SharedPBit1());
1309 subsets[0][0].rgb = (subsets[0][0].rgb << 1) | pbit0;
1310 subsets[0][1].rgb = (subsets[0][1].rgb << 1) | pbit0;
1311 subsets[1][0].rgb = (subsets[1][0].rgb << 1) | pbit1;
1312 subsets[1][1].rgb = (subsets[1][1].rgb << 1) | pbit1;
1313 }
1314
1315 if (mode.EPB > 0) {
1316 for (size_t i = 0; i < mode.NS; i++) {
1317 auto &subset = subsets[i];
1318 auto pbit0 = Get(mode.EndpointPBit(i * 2 + 0));
1319 auto pbit1 = Get(mode.EndpointPBit(i * 2 + 1));
1320 subset[0].rgb = (subset[0].rgb << 1) | pbit0;
1321 subset[1].rgb = (subset[1].rgb << 1) | pbit1;
1322 if (mode.AB > 0) {
1323 subset[0].a = (subset[0].a << 1) | pbit0;
1324 subset[1].a = (subset[1].a << 1) | pbit1;
1325 }
1326 }
1327 }
1328
1329 auto const colorBits = mode.CB + mode.SPB + mode.EPB;
1330 auto const alphaBits = mode.AB + mode.SPB + mode.EPB;
1331
1332 for (size_t i = 0; i < mode.NS; i++) {
1333 auto &subset = subsets[i];
1334 subset[0].rgb = subset[0].rgb << (8 - colorBits);
1335 subset[1].rgb = subset[1].rgb << (8 - colorBits);
1336 subset[0].rgb = subset[0].rgb | (subset[0].rgb >> colorBits);
1337 subset[1].rgb = subset[1].rgb | (subset[1].rgb >> colorBits);
1338
1339 if (mode.AB > 0) {
1340 subset[0].a = subset[0].a << (8 - alphaBits);
1341 subset[1].a = subset[1].a << (8 - alphaBits);
1342 subset[0].a = subset[0].a | (subset[0].a >> alphaBits);
1343 subset[1].a = subset[1].a | (subset[1].a >> alphaBits);
1344 }
1345 }
1346
1347 int colorIndexBitOffset = 0;
1348 int alphaIndexBitOffset = 0;
1349 for (int y = 0; y < 4; y++) {
1350 for (int x = 0; x < 4; x++) {
1351 auto texelIdx = y * 4 + x;
1352 auto partitionIdx = Get(mode.Partition());
1353 assert(partitionIdx < MaxPartitions);
1354 auto subsetIdx = subsetIndex(mode, partitionIdx, texelIdx);
1355 assert(subsetIdx < MaxSubsets);
1356 auto const &subset = subsets[subsetIdx];
1357
1358 auto anchorIdx = anchorIndex(mode, partitionIdx, subsetIdx);
1359 auto isAnchor = anchorIdx == texelIdx;
1360 auto colorIdx = colorIndex(mode, isAnchor, colorIndexBitOffset);
1361 auto alphaIdx = alphaIndex(mode, isAnchor, alphaIndexBitOffset);
1362
1363 if (y + dstY >= dstHeight || x + dstX >= dstWidth) {
1364 // Don't be tempted to skip early at the loops:
1365 // The calls to colorIndex() and alphaIndex() adjust bit
1366 // offsets that need to be carefully tracked.
1367 continue;
1368 }
1369
1370 Color output;
1371 // Note: We flip r and b channels past this point as the texture storage is BGR while the output is RGB
1372 output.rgb.r = interpolate(subset[0].rgb.b, subset[1].rgb.b, colorIdx);
1373 output.rgb.g = interpolate(subset[0].rgb.g, subset[1].rgb.g, colorIdx);
1374 output.rgb.b = interpolate(subset[0].rgb.r, subset[1].rgb.r, colorIdx);
1375 output.a = interpolate(subset[0].a, subset[1].a, alphaIdx);
1376
1377 switch (Get(mode.Rotation())) {
1378 default:
1379 break;
1380 case 1:
1381 std::swap(output.a, output.rgb.b);
1382 break;
1383 case 2:
1384 std::swap(output.a, output.rgb.g);
1385 break;
1386 case 3:
1387 std::swap(output.a, output.rgb.r);
1388 break;
1389 }
1390
1391 auto out = reinterpret_cast<Color *>(dst + sizeof(Color) * x + dstPitch * y);
1392 *out = output;
1393 }
1394 }
1395 }
1396
1397 int subsetIndex(const Mode &mode, int partitionIdx, int texelIndex) const {
1398 switch (mode.NS) {
1399 default:
1400 return 0;
1401 case 2:
1402 return PartitionTable2[partitionIdx][texelIndex];
1403 case 3:
1404 return PartitionTable3[partitionIdx][texelIndex];
1405 }
1406 }
1407
1408 int anchorIndex(const Mode &mode, int partitionIdx, int subsetIdx) const {
1409 // ARB_texture_compression_bptc states:
1410 // "In partition zero, the anchor index is always index zero.
1411 // In other partitions, the anchor index is specified by tables
1412 // Table.A2 and Table.A3.""
1413 // Note: This is really confusing - I believe they meant subset instead
1414 // of partition here.
1415 switch (subsetIdx) {
1416 default:
1417 return 0;
1418 case 1:
1419 return mode.NS == 2 ? AnchorTable2[partitionIdx] : AnchorTable3a[partitionIdx];
1420 case 2:
1421 return AnchorTable3b[partitionIdx];
1422 }
1423 }
1424
1425 IndexInfo colorIndex(const Mode &mode, bool isAnchor,
1426 int &indexBitOffset) const {
1427 // ARB_texture_compression_bptc states:
1428 // "The index value for interpolating color comes from the secondary
1429 // index for the texel if the format has an index selection bit and its
1430 // value is one and from the primary index otherwise.""
1431 auto idx = Get(mode.IndexSelection());
1432 assert(idx <= 1);
1433 bool secondary = idx == 1;
1434 auto numBits = secondary ? mode.IB2 : mode.IB;
1435 auto numReadBits = numBits - (isAnchor ? 1 : 0);
1436 auto index =
1437 Get(secondary ? mode.SecondaryIndex(indexBitOffset, numReadBits)
1438 : mode.PrimaryIndex(indexBitOffset, numReadBits));
1439 indexBitOffset += numReadBits;
1440 return {index, numBits};
1441 }
1442
1443 IndexInfo alphaIndex(const Mode &mode, bool isAnchor,
1444 int &indexBitOffset) const {
1445 // ARB_texture_compression_bptc states:
1446 // "The alpha index comes from the secondary index if the block has a
1447 // secondary index and the block either doesn't have an index selection
1448 // bit or that bit is zero and the primary index otherwise."
1449 auto idx = Get(mode.IndexSelection());
1450 assert(idx <= 1);
1451 bool secondary = (mode.IB2 != 0) && (idx == 0);
1452 auto numBits = secondary ? mode.IB2 : mode.IB;
1453 auto numReadBits = numBits - (isAnchor ? 1 : 0);
1454 auto index =
1455 Get(secondary ? mode.SecondaryIndex(indexBitOffset, numReadBits)
1456 : mode.PrimaryIndex(indexBitOffset, numReadBits));
1457 indexBitOffset += numReadBits;
1458 return {index, numBits};
1459 }
1460
1461 // Assumes little-endian
1462 uint64_t low;
1463 uint64_t high;
1464 };
1465
1466 } // namespace BC7
1467} // anonymous namespace
1468
1469namespace bcn {
1470 constexpr size_t R8Bpp{1}; //!< The amount of bytes per pixel in R8
1471 constexpr size_t R8g8Bpp{2}; //!< The amount of bytes per pixel in R8G8
1472 constexpr size_t R8g8b8a8Bpp{4}; //!< The amount of bytes per pixel in R8G8B8A8
1473 constexpr size_t R16g16b16a16Bpp{8}; //!< The amount of bytes per pixel in R16G16B16
1474
1475 void DecodeBc1(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height) {
1476 const auto *color{reinterpret_cast<const BC_color *>(src)};
1477 size_t pitch{R8g8b8a8Bpp * width};
1478 color->decode(dst, x, y, width, height, pitch, R8g8b8a8Bpp, true, false);
1479 }
1480
1481 void DecodeBc2(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height) {
1482 const auto *alpha{reinterpret_cast<const BC_alpha *>(src)};
1483 const auto *color{reinterpret_cast<const BC_color *>(src + 8)};
1484 size_t pitch{R8g8b8a8Bpp * width};
1485 color->decode(dst, x, y, width, height, pitch, R8g8b8a8Bpp, false, true);
1486 alpha->decode(dst, x, y, width, height, pitch, R8g8b8a8Bpp);
1487 }
1488
1489 void DecodeBc3(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height) {
1490 const auto *alpha{reinterpret_cast<const BC_channel *>(src)};
1491 const auto *color{reinterpret_cast<const BC_color *>(src + 8)};
1492 size_t pitch{R8g8b8a8Bpp * width};
1493 color->decode(dst, x, y, width, height, pitch, R8g8b8a8Bpp, false, true);
1494 alpha->decode(dst, x, y, width, height, pitch, R8g8b8a8Bpp, 3, false);
1495 }
1496
1497 void DecodeBc4(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height, bool isSigned) {
1498 const auto *red{reinterpret_cast<const BC_channel *>(src)};
1499 size_t pitch{R8Bpp * width};
1500 red->decode(dst, x, y, width, height, pitch, R8Bpp, 0, isSigned);
1501 }
1502
1503 void DecodeBc5(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height, bool isSigned) {
1504 const auto *red{reinterpret_cast<const BC_channel *>(src)};
1505 const auto *green{reinterpret_cast<const BC_channel *>(src + 8)};
1506 size_t pitch{R8g8Bpp * width};
1507 red->decode(dst, x, y, width, height, pitch, R8g8Bpp, 0, isSigned);
1508 green->decode(dst, x, y, width, height, pitch, R8g8Bpp, 1, isSigned);
1509 }
1510
1511 void DecodeBc6(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height, bool isSigned) {
1512 const auto *block{reinterpret_cast<const BC6H::Block *>(src)};
1513 size_t pitch{R16g16b16a16Bpp * width};
1514 block->decode(dst, x, y, width, height, pitch, R16g16b16a16Bpp, isSigned);
1515 }
1516
1517 void DecodeBc7(const uint8_t *src, uint8_t *dst, size_t x, size_t y, size_t width, size_t height) {
1518 const auto *block{reinterpret_cast<const BC7::Block *>(src)};
1519 size_t pitch{R8g8b8a8Bpp * width};
1520 block->decode(dst, x, y, width, height, pitch);
1521 }
1522}
HIC SVNT DRACONES