mirror of https://github.com/phoboslab/qoi.git
Align the data format with new spec #37
This commit is contained in:
Dominic Szablewski
parent
a902b57ede
commit
697abf6696
134
qoi.h
134
qoi.h
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@ -75,10 +75,14 @@ you can define QOI_MALLOC and QOI_FREE before including this library.
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A QOI file has a 12 byte header, followed by any number of data "chunks".
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struct qoi_header_t {
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char [4]; // magic bytes "qoif"
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unsigned short width; // image width in pixels (BE)
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unsigned short height; // image height in pixels (BE)
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unsigned int size; // number of data bytes following this header (BE)
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char magic[4]; // magic bytes "qoif"
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uint32_t width; // image width in pixels (BE)
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uint32_t height; // image height in pixels (BE)
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uint8_t channels; // must be 3 (RGB) or 4 (RGBA)
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uint8_t colorspace; // a bitmap 0000rgba where
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// - a zero bit indicates sRGBA,
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// - a one bit indicates linear (user interpreted)
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// colorspace for each channel
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};
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The decoder and encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous
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@ -113,24 +117,24 @@ QOI_RUN_16 {
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QOI_DIFF_8 {
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u8 tag : 2; // b10
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u8 dr : 2; // 2-bit red channel difference: -1..2
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u8 dg : 2; // 2-bit green channel difference: -1..2
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u8 db : 2; // 2-bit blue channel difference: -1..2
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u8 dr : 2; // 2-bit red channel difference: -2..1
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u8 dg : 2; // 2-bit green channel difference: -2..1
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u8 db : 2; // 2-bit blue channel difference: -2..1
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}
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QOI_DIFF_16 {
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u8 tag : 3; // b110
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u8 dr : 5; // 5-bit red channel difference: -15..16
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u8 dg : 4; // 4-bit green channel difference: -7.. 8
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u8 db : 4; // 4-bit blue channel difference: -7.. 8
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u8 dr : 5; // 5-bit red channel difference: -16..15
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u8 dg : 4; // 4-bit green channel difference: -8.. 7
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u8 db : 4; // 4-bit blue channel difference: -8.. 7
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}
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QOI_DIFF_24 {
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u8 tag : 4; // b1110
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u8 dr : 5; // 5-bit red channel difference: -15..16
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u8 dg : 5; // 5-bit green channel difference: -15..16
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u8 db : 5; // 5-bit blue channel difference: -15..16
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u8 da : 5; // 5-bit alpha channel difference: -15..16
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u8 dr : 5; // 5-bit red channel difference: -16..15
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u8 dg : 5; // 5-bit green channel difference: -16..15
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u8 db : 5; // 5-bit blue channel difference: -16..15
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u8 da : 5; // 5-bit alpha channel difference: -16..15
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}
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QOI_COLOR {
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@ -246,26 +250,19 @@ typedef union {
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unsigned int v;
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} qoi_rgba_t;
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void qoi_write_16(unsigned char *bytes, int *p, unsigned short v) {
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bytes[(*p)++] = (0xff00 & v) >> 8;
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bytes[(*p)++] = (0xff & v);
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}
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void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
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qoi_write_16(bytes, p, (v & 0xffff0000) >> 16);
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qoi_write_16(bytes, p, (v & 0xffff));
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}
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unsigned int qoi_read_16(const unsigned char *bytes, int *p) {
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unsigned int a = bytes[(*p)++];
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unsigned int b = bytes[(*p)++];
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return (a << 8) | b;
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bytes[(*p)++] = (0xff000000 & v) >> 24;
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bytes[(*p)++] = (0x00ff0000 & v) >> 16;
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bytes[(*p)++] = (0x0000ff00 & v) >> 8;
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bytes[(*p)++] = (0x000000ff & v);
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}
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unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
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unsigned int a = qoi_read_16(bytes, p);
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unsigned int b = qoi_read_16(bytes, p);
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return (a << 16) | b;
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unsigned int a = bytes[(*p)++];
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unsigned int b = bytes[(*p)++];
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unsigned int c = bytes[(*p)++];
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unsigned int d = bytes[(*p)++];
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return (a << 24) | (b << 16) | (c << 8) | d;
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}
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void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
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@ -286,9 +283,10 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
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}
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qoi_write_32(bytes, &p, QOI_MAGIC);
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qoi_write_16(bytes, &p, w);
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qoi_write_16(bytes, &p, h);
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qoi_write_32(bytes, &p, 0); // size, will be set later
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qoi_write_32(bytes, &p, w);
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qoi_write_32(bytes, &p, h);
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bytes[p++] = channels;
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bytes[p++] = 0; // TODO: accept a colorspace as a parameter to this function
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const unsigned char *pixels = (const unsigned char *)data;
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@ -342,26 +340,26 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
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int va = px.rgba.a - px_prev.rgba.a;
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if (
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vr > -16 && vr < 17 && vg > -16 && vg < 17 &&
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vb > -16 && vb < 17 && va > -16 && va < 17
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vr > -17 && vr < 16 && vg > -17 && vg < 16 &&
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vb > -17 && vb < 16 && va > -17 && va < 16
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) {
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if (
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va == 0 && vr > -2 && vr < 3 &&
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vg > -2 && vg < 3 && vb > -2 && vb < 3
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va == 0 && vr > -3 && vr < 2 &&
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vg > -3 && vg < 2 && vb > -3 && vb < 2
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) {
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bytes[p++] = QOI_DIFF_8 | ((vr + 1) << 4) | (vg + 1) << 2 | (vb + 1);
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bytes[p++] = QOI_DIFF_8 | ((vr + 2) << 4) | (vg + 2) << 2 | (vb + 2);
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}
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else if (
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va == 0 && vr > -16 && vr < 17 &&
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vg > -8 && vg < 9 && vb > -8 && vb < 9
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va == 0 && vr > -17 && vr < 16 &&
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vg > -9 && vg < 8 && vb > -9 && vb < 8
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) {
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bytes[p++] = QOI_DIFF_16 | (vr + 15);
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bytes[p++] = ((vg + 7) << 4) | (vb + 7);
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bytes[p++] = QOI_DIFF_16 | (vr + 16);
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bytes[p++] = ((vg + 8) << 4) | (vb + 8);
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}
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else {
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bytes[p++] = QOI_DIFF_24 | ((vr + 15) >> 1);
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bytes[p++] = ((vr + 15) << 7) | ((vg + 15) << 2) | ((vb + 15) >> 3);
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bytes[p++] = ((vb + 15) << 5) | (va + 15);
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bytes[p++] = QOI_DIFF_24 | ((vr + 16) >> 1);
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bytes[p++] = ((vr + 16) << 7) | ((vg + 16) << 2) | ((vb + 16) >> 3);
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bytes[p++] = ((vb + 16) << 5) | (va + 16);
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}
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}
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else {
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@ -380,35 +378,33 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
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bytes[p++] = 0;
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}
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int data_len = p - QOI_HEADER_SIZE;
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*out_len = p;
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p = 8;
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qoi_write_32(bytes, &p, data_len);
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return bytes;
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}
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void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channels) {
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if (channels < 3 || channels > 4 || size < QOI_HEADER_SIZE) {
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if (channels < 3 || channels > 4 || size < QOI_HEADER_SIZE + QOI_PADDING) {
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return NULL;
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}
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const unsigned char *bytes = (const unsigned char *)data;
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int p = 0;
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int magic = qoi_read_32(bytes, &p);
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int w = qoi_read_16(bytes, &p);
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int h = qoi_read_16(bytes, &p);
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int data_len = qoi_read_32(bytes, &p);
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unsigned int header_magic = qoi_read_32(bytes, &p);
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unsigned int header_w = qoi_read_32(bytes, &p);
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unsigned int header_h = qoi_read_32(bytes, &p);
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unsigned int header_channels = bytes[p++];
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unsigned int header_colorspace = bytes[p++];
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if (
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w == 0 || h == 0 || magic != QOI_MAGIC ||
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size != data_len + QOI_HEADER_SIZE
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header_w == 0 || header_h == 0 ||
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header_channels < 3 || header_channels > 4 ||
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header_magic != QOI_MAGIC
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) {
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return NULL;
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}
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int px_len = w * h * channels;
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int px_len = header_w * header_h * channels;
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unsigned char *pixels = QOI_MALLOC(px_len);
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if (!pixels) {
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return NULL;
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@ -437,23 +433,23 @@ void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channel
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run = (((b1 & 0x1f) << 8) | (b2)) + 32;
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}
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else if ((b1 & QOI_MASK_2) == QOI_DIFF_8) {
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px.rgba.r += ((b1 >> 4) & 0x03) - 1;
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px.rgba.g += ((b1 >> 2) & 0x03) - 1;
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px.rgba.b += ( b1 & 0x03) - 1;
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px.rgba.r += ((b1 >> 4) & 0x03) - 2;
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px.rgba.g += ((b1 >> 2) & 0x03) - 2;
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px.rgba.b += ( b1 & 0x03) - 2;
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}
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else if ((b1 & QOI_MASK_3) == QOI_DIFF_16) {
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int b2 = bytes[p++];
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px.rgba.r += (b1 & 0x1f) - 15;
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px.rgba.g += (b2 >> 4) - 7;
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px.rgba.b += (b2 & 0x0f) - 7;
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px.rgba.r += (b1 & 0x1f) - 16;
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px.rgba.g += (b2 >> 4) - 8;
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px.rgba.b += (b2 & 0x0f) - 8;
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}
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else if ((b1 & QOI_MASK_4) == QOI_DIFF_24) {
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int b2 = bytes[p++];
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int b3 = bytes[p++];
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px.rgba.r += (((b1 & 0x0f) << 1) | (b2 >> 7)) - 15;
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px.rgba.g += ((b2 & 0x7c) >> 2) - 15;
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px.rgba.b += (((b2 & 0x03) << 3) | ((b3 & 0xe0) >> 5)) - 15;
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px.rgba.a += (b3 & 0x1f) - 15;
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px.rgba.r += (((b1 & 0x0f) << 1) | (b2 >> 7)) - 16;
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px.rgba.g += ((b2 & 0x7c) >> 2) - 16;
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px.rgba.b += (((b2 & 0x03) << 3) | ((b3 & 0xe0) >> 5)) - 16;
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px.rgba.a += (b3 & 0x1f) - 16;
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}
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else if ((b1 & QOI_MASK_4) == QOI_COLOR) {
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if (b1 & 8) { px.rgba.r = bytes[p++]; }
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@ -475,8 +471,8 @@ void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channel
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}
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}
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*out_w = w;
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*out_h = h;
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*out_w = header_w;
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*out_h = header_h;
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return pixels;
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}
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