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Faster decode #255

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Faster decode #255

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3b0bb8c
Don't hash on run or index
andrews05 Jan 7, 2023
b8c8866
Use incrementing pointer when reading
andrews05 Jan 10, 2023
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75 changes: 42 additions & 33 deletions qoi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -345,11 +345,11 @@ static void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
bytes[(*p)++] = (0x000000ff & v);
}

static unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
unsigned int a = bytes[(*p)++];
unsigned int b = bytes[(*p)++];
unsigned int c = bytes[(*p)++];
unsigned int d = bytes[(*p)++];
static unsigned int qoi_read_32(unsigned char **bytes) {
unsigned int a = *(*bytes)++;
unsigned int b = *(*bytes)++;
unsigned int c = *(*bytes)++;
unsigned int d = *(*bytes)++;
return a << 24 | b << 16 | c << 8 | d;
}

Expand Down Expand Up @@ -486,13 +486,15 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
}

void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
const unsigned char *bytes;
unsigned char *bytes;
const unsigned char *bytes_end;
unsigned int header_magic;
unsigned char *pixels;
unsigned char *pixels, *px_pos;
const unsigned char *px_end;
qoi_rgba_t index[64];
qoi_rgba_t px;
int px_len, chunks_len, px_pos;
int p = 0, run = 0;
int px_len;
int run = 0;

if (
data == NULL || desc == NULL ||
Expand All @@ -502,13 +504,14 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
return NULL;
}

bytes = (const unsigned char *)data;
bytes = (unsigned char *)data;
bytes_end = bytes + size - (int)sizeof(qoi_padding);

header_magic = qoi_read_32(bytes, &p);
desc->width = qoi_read_32(bytes, &p);
desc->height = qoi_read_32(bytes, &p);
desc->channels = bytes[p++];
desc->colorspace = bytes[p++];
header_magic = qoi_read_32(&bytes);
desc->width = qoi_read_32(&bytes);
desc->height = qoi_read_32(&bytes);
desc->channels = *bytes++;
desc->colorspace = *bytes++;

if (
desc->width == 0 || desc->height == 0 ||
Expand All @@ -529,31 +532,33 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
if (!pixels) {
return NULL;
}
px_end = pixels + px_len;

QOI_ZEROARR(index);
px.rgba.r = 0;
px.rgba.g = 0;
px.rgba.b = 0;
px.rgba.a = 255;

chunks_len = size - (int)sizeof(qoi_padding);
for (px_pos = 0; px_pos < px_len; px_pos += channels) {
for (px_pos = pixels; px_pos < px_end;) {
if (run > 0) {
run--;
}
else if (p < chunks_len) {
int b1 = bytes[p++];
else if (bytes < bytes_end) {
int b1 = *bytes++;

if (b1 == QOI_OP_RGB) {
px.rgba.r = bytes[p++];
px.rgba.g = bytes[p++];
px.rgba.b = bytes[p++];
px.rgba.r = *bytes++;
px.rgba.g = *bytes++;
px.rgba.b = *bytes++;
index[QOI_COLOR_HASH(px) % 64] = px;
}
else if (b1 == QOI_OP_RGBA) {
px.rgba.r = bytes[p++];
px.rgba.g = bytes[p++];
px.rgba.b = bytes[p++];
px.rgba.a = bytes[p++];
px.rgba.r = *bytes++;
px.rgba.g = *bytes++;
px.rgba.b = *bytes++;
px.rgba.a = *bytes++;
index[QOI_COLOR_HASH(px) % 64] = px;
}
else if ((b1 & QOI_MASK_2) == QOI_OP_INDEX) {
px = index[b1];
Expand All @@ -562,27 +567,31 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
px.rgba.r += ((b1 >> 4) & 0x03) - 2;
px.rgba.g += ((b1 >> 2) & 0x03) - 2;
px.rgba.b += ( b1 & 0x03) - 2;
index[QOI_COLOR_HASH(px) % 64] = px;
}
else if ((b1 & QOI_MASK_2) == QOI_OP_LUMA) {
int b2 = bytes[p++];
int b2 = *bytes++;
int vg = (b1 & 0x3f) - 32;
px.rgba.r += vg - 8 + ((b2 >> 4) & 0x0f);
px.rgba.g += vg;
px.rgba.b += vg - 8 + (b2 & 0x0f);
index[QOI_COLOR_HASH(px) % 64] = px;
}
else if ((b1 & QOI_MASK_2) == QOI_OP_RUN) {
else { // QOI_OP_RUN
run = (b1 & 0x3f);
if (px_pos == pixels) {
index[QOI_COLOR_HASH(px) % 64] = px;
}
}

index[QOI_COLOR_HASH(px) % 64] = px;
}

pixels[px_pos + 0] = px.rgba.r;
pixels[px_pos + 1] = px.rgba.g;
pixels[px_pos + 2] = px.rgba.b;
*px_pos++ = px.rgba.r;
*px_pos++ = px.rgba.g;
*px_pos++ = px.rgba.b;

if (channels == 4) {
pixels[px_pos + 3] = px.rgba.a;
*px_pos++ = px.rgba.a;
}
}

Expand Down