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various pqoi fixes
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@profezzorn
profezzorn committed Dec 5, 2023
1 parent 8037afa commit 1eaf015
Showing 1 changed file with 65 additions and 27 deletions.
92 changes: 65 additions & 27 deletions pqoi/pqoi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,12 +14,11 @@

// QOI-inspired format for 16-bit RGB565 images and animations.

// 0b00000000 (0) = reserved
// 0b0NNNNNNN (1-123) = delta
// 0b01111100 (124) = copy 2
// 0b01111101 (125) = copy 4
// 0b01111110 (126) = copy 4x2
// 0b01111111 (127) = color is next 2 bytes
// 0b00000000 (0) = color is next 2 bytes
// 0b0NNNNNNN (1-124) = delta
// 0b01111100 (125) = copy 2
// 0b01111101 (126) = copy 4
// 0b01111110 (127) = copy 4x2
// 0b100NNNNN (128 ... 159) = run
// 0b101GGGGG 0bRRRRBBBB (160 ... 191) = extended delta
// 0b11NNNNNN = (192..255) from stash
Expand Down Expand Up @@ -64,23 +63,29 @@ uint16_t const PqoiBase::deltas[125] = { PQOI_DELTA3(0) };
#define PQOI_DECODE_ONE(GETC) \
GETC(AT_START); \
switch (byte) { \
case 0: \
case 1 ... 123: \
case 0: { /* raw bytes */ \
GETC(AT_RAW1); \
b2 = byte; \
GETC(AT_RAW2); \
pixel_ = (byte << 8) + b2; \
break; \
} \
case 1 ... 124: \
pixel_ += deltas[byte]; \
break; \
case 124: /* copy 2 */ \
case 125: /* copy 2 */ \
out[0] = out[-2]; \
out[1] = out[-1]; \
out += 2; \
continue; \
case 125: /* copy 4 */ \
case 126: /* copy 4 */ \
out[0] = out[-4]; \
out[1] = out[-3]; \
out[2] = out[-2]; \
out[3] = out[-1]; \
out += 4; \
continue; \
case 126: /* copy 4x2 */ \
case 127: /* copy 4x2 */ \
out[0] = out[-4]; \
out[1] = out[-3]; \
out[2] = out[-2]; \
Expand All @@ -91,13 +96,6 @@ uint16_t const PqoiBase::deltas[125] = { PQOI_DELTA3(0) };
out[7] = out[-1]; \
out += 8; \
continue; \
case 127: { /* raw bytes */ \
GETC(AT_RAW1); \
b2 = byte; \
GETC(AT_RAW2); \
pixel_ = (byte << 8) + b2; \
break; \
} \
case 159: *(out++) = pixel_; \
case 158: *(out++) = pixel_; \
case 157: *(out++) = pixel_; \
Expand Down Expand Up @@ -251,6 +249,10 @@ struct PqoiOutputChunk {
end_ = begin();
}

void init(int left) {
end_ = begin() + left;
}

void init_next_chunk(PqoiOutputChunk* previous) {
// Previous must be full()
size_t pad = previous->end_ - previous->chunk_end();
Expand All @@ -261,11 +263,22 @@ struct PqoiOutputChunk {
end_ = begin() + pad;
}

void init_next_chunk(PqoiOutputChunk* previous, int left, int pixels) {
// Previous must be full()
size_t pad = previous->end_ - (previous->begin() + left + pixels);
size_t history = 0;
if (pad < 4) history = 4 - pad;
size_t to_copy = history + pad;
memcpy(begin() + left - history, previous->end_ - to_copy, to_copy * 2);
end_ = begin() + left + pad;
}

uint16_t* begin() { return pixels + HISTORY; }
uint16_t* chunk_end() { return begin() + CHUNK_SIZE; }
uint16_t* end() { return std::min(end_, chunk_end()); }
size_t size() { return end() - begin(); }
bool full() { return size() >= CHUNK_SIZE; }
bool full(int left, int pixels) { return size() >= pixels + left; }
uint16_t* data_end() { return end_; }

template<class PQOI_DECODER>
Expand All @@ -276,10 +289,29 @@ struct PqoiOutputChunk {
return size() >= pixels;
}

template<class PQOI_DECODER>
bool fill(PQOI_DECODER* decoder, size_t left, size_t pixels) {
if (size() >= pixels + left) return true;
uint16_t* read_end = std::min(chunk_end(), begin() + pixels + left);
end_ = decoder->read(end_, read_end);
return size() >= pixels + left;
}

void zero() {
memset(begin(), 0, CHUNK_SIZE * 2);
end_ = chunk_end();
}
void zero(size_t left,size_t pixels) {
memset(begin() + left, 0, pixels * 2);
end_ = begin() + left + pixels;
}
void zero_margins(size_t left, size_t pixels) {
if (left) memset(begin(), 0, left * 2);
if (left + pixels < CHUNK_SIZE) {
memset(begin() + left + pixels, 0, (CHUNK_SIZE - left - pixels) * 2);
}
end_ = chunk_end();
}

uint16_t* end_;
uint16_t pixels[HISTORY + CHUNK_SIZE + PAD];
Expand All @@ -298,7 +330,7 @@ struct PqoiLookupTable {
}
}
}
for (size_t i = 1; i < 124; i++) {
for (size_t i = 1; i < 125; i++) {
diff_index[PqoiBase::deltas[i]] = i;
}
}
Expand All @@ -322,23 +354,23 @@ class PqoiEncoder : public PqoiBase {
if (stash_[h] == pixel) {
op = h + 192;
} else if (op == 0) {
op = (127 << 16) | ((pixel & 0xff) << 8) | (pixel >> 8);
op = (0x100 << 16) | ((pixel & 0xff) << 8) | (pixel >> 8);
}
// Check run and copy operations
#if 1
if (pixels - begin >= 2 && end - pixels >= 2 &&
pixels[0] == pixels[-2] &&
pixels[1] == pixels[-1]) {
l = 2;
op = 124;
op = 125;
}
if (pixels - begin >= 4 && end - pixels >= 4 &&
pixels[0] == pixels[-4] &&
pixels[1] == pixels[-3] &&
pixels[2] == pixels[-2] &&
pixels[3] == pixels[-1]) {
l = 4;
op = 125;
op = 126;
}
if (pixels - begin >= 8 && end - pixels >= 8 &&
pixels[0] == pixels[-4] &&
Expand All @@ -350,7 +382,7 @@ class PqoiEncoder : public PqoiBase {
pixels[6] == pixels[-2] &&
pixels[7] == pixels[-1]) {
l = 8;
op = 126;
op = 127;
}
#endif
if (pixel == pixel_) {
Expand Down Expand Up @@ -669,9 +701,9 @@ class AlphaEncoder : public PqoiEncoder {
// premultiply
A = (255 - A) * 33 >> 8;
int Ainv = 32 - A;
R = (R * Ainv) >> 6;
G = (G * Ainv) >> 6;
B = (B * Ainv) >> 6;
R = (R * Ainv) >> 5;
G = (G * Ainv) >> 5;
B = (B * Ainv) >> 5;
ret.alphas.push_back(A);
if (A) opaque = false;
}
Expand Down Expand Up @@ -720,7 +752,13 @@ class AlphaEncoder : public PqoiEncoder {
// Add header....
AlphaEncoder encoder;
magic = "PQOA";
end = encoder.encodePixelsWithAlpha(data.pixels.data(), data.pixels.data() + pixels, data.alphas.data(), ret.data() + 16);
end = ret.data() + 16;
// Alpha data must be encoded one row at a time, or per-row decoding becomes too complicated
for (int row = 0; row < data.h; row++) {
const uint16_t *pixel_row = data.pixels.data() + data.w * row;
const uint8_t *alpha_row = data.alphas.data() + data.w * row;
end = encoder.encodePixelsWithAlpha(pixel_row, pixel_row + data.w, alpha_row, end);
}
}
size_t size = end - ret.data();
ret.resize(size);
Expand Down

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