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Do not convert BC1 LUT to UINT32 #8837

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Merged
radarhere merged 1 commit into from
Mar 27, 2025
Merged

Do not convert BC1 LUT to UINT32 #8837

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14 changes: 6 additions & 8 deletions src/libImaging/BcnDecode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,6 @@ typedef struct {

typedef struct {
UINT16 c0, c1;
UINT32 lut;
} bc1_color;

typedef struct {
Expand All @@ -40,13 +39,10 @@ typedef struct {

#define LOAD16(p) (p)[0] | ((p)[1] << 8)

#define LOAD32(p) (p)[0] | ((p)[1] << 8) | ((p)[2] << 16) | ((p)[3] << 24)

static void
bc1_color_load(bc1_color *dst, const UINT8 *src) {
dst->c0 = LOAD16(src);
dst->c1 = LOAD16(src + 2);
dst->lut = LOAD32(src + 4);
}

static rgba
Expand All @@ -70,7 +66,7 @@ static void
decode_bc1_color(rgba *dst, const UINT8 *src, int separate_alpha) {
bc1_color col;
rgba p[4];
int n, cw;
int n, o, cw;
UINT16 r0, g0, b0, r1, g1, b1;
bc1_color_load(&col, src);

Expand Down Expand Up @@ -103,9 +99,11 @@ decode_bc1_color(rgba *dst, const UINT8 *src, int separate_alpha) {
p[3].b = 0;
p[3].a = 0;
}
for (n = 0; n < 16; n++) {
cw = 3 & (col.lut >> (2 * n));
dst[n] = p[cw];
for (n = 0; n < 4; n++) {
for (o = 0; o < 4; o++) {
cw = 3 & ((src + 4)[n] >> (2 * o));
dst[n * 4 + o] = p[cw];
}
}
}

Expand Down
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