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reactos/dll/3rdparty/dxtn/dxtn.c

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/*
* DXTn codec
* Version: 1.1
*
* Copyright (C) 2004 Daniel Borca All Rights Reserved.
*
* this is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* this is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Make; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <string.h>
#include "types.h"
#include "internal.h"
#include "dxtn.h"
/***************************************************************************\
* DXTn encoder
*
* The encoder was built by reversing the decoder,
* and is vaguely based on FXT1 codec. Note that this code
* is merely a proof of concept, since it is highly UNoptimized!
\***************************************************************************/
#define MAX_COMP 4 /* ever needed maximum number of components in texel */
#define MAX_VECT 4 /* ever needed maximum number of base vectors to find */
#define N_TEXELS 16 /* number of texels in a block (always 16) */
#define COLOR565(v) (word)((((v)[RCOMP] & 0xf8) << 8) | (((v)[GCOMP] & 0xfc) << 3) | ((v)[BCOMP] >> 3))
static const int dxtn_color_tlat[2][4] = {
{ 0, 2, 3, 1 },
{ 0, 2, 1, 3 }
};
static const int dxtn_alpha_tlat[2][8] = {
{ 0, 2, 3, 4, 5, 6, 7, 1 },
{ 0, 2, 3, 4, 5, 1, 6, 7 }
};
static void
dxt1_rgb_quantize (dword *cc, const byte *lines[], int comps)
{
float b, iv[MAX_COMP]; /* interpolation vector */
dword hi; /* high doubleword */
int color0, color1;
int n_vect;
const int n_comp = 3;
int black = 0;
int minSum = 2000; /* big enough */
int maxSum = -1; /* small enough */
int minCol = 0; /* phoudoin: silent compiler! */
int maxCol = 0; /* phoudoin: silent compiler! */
byte input[N_TEXELS][MAX_COMP];
int i, k, l;
/* make the whole block opaque */
/* we will NEVER reference ACOMP of any pixel */
/* 4 texels each line */
for (l = 0; l < 4; l++) {
for (k = 0; k < 4; k++) {
for (i = 0; i < comps; i++) {
input[k + l * 4][i] = *lines[l]++;
}
}
}
/* Our solution here is to find the darkest and brightest colors in
* the 4x4 tile and use those as the two representative colors.
* There are probably better algorithms to use (histogram-based).
*/
for (k = 0; k < N_TEXELS; k++) {
int sum = 0;
for (i = 0; i < n_comp; i++) {
sum += input[k][i];
}
if (minSum > sum) {
minSum = sum;
minCol = k;
}
if (maxSum < sum) {
maxSum = sum;
maxCol = k;
}
if (sum == 0) {
black = 1;
}
}
color0 = COLOR565(input[minCol]);
color1 = COLOR565(input[maxCol]);
if (color0 == color1) {
/* we'll use 3-vector */
cc[0] = color0 | (color1 << 16);
hi = black ? -1 : 0;
} else {
if (black && ((color0 == 0) || (color1 == 0))) {
/* we still can use 4-vector */
black = 0;
}
if (black ^ (color0 <= color1)) {
int aux;
aux = color0;
color0 = color1;
color1 = aux;
aux = minCol;
minCol = maxCol;
maxCol = aux;
}
n_vect = (color0 <= color1) ? 2 : 3;
MAKEIVEC(n_vect, n_comp, iv, b, input[minCol], input[maxCol]);
/* add in texels */
cc[0] = color0 | (color1 << 16);
hi = 0;
for (k = N_TEXELS - 1; k >= 0; k--) {
int texel = 3;
int sum = 0;
if (black) {
for (i = 0; i < n_comp; i++) {
sum += input[k][i];
}
}
if (!black || sum) {
/* interpolate color */
CALCCDOT(texel, n_vect, n_comp, iv, b, input[k]);
texel = dxtn_color_tlat[black][texel];
}
/* add in texel */
hi <<= 2;
hi |= texel;
}
}
cc[1] = hi;
}
static void
dxt1_rgba_quantize (dword *cc, const byte *lines[], int comps)
{
float b, iv[MAX_COMP]; /* interpolation vector */
dword hi; /* high doubleword */
int color0, color1;
int n_vect;
const int n_comp = 3;
int transparent = 0;
int minSum = 2000; /* big enough */
int maxSum = -1; /* small enough */
int minCol = 0; /* phoudoin: silent compiler! */
int maxCol = 0; /* phoudoin: silent compiler! */
byte input[N_TEXELS][MAX_COMP];
int i, k, l;
if (comps == 3) {
/* make the whole block opaque */
memset(input, -1, sizeof(input));
}
/* 4 texels each line */
for (l = 0; l < 4; l++) {
for (k = 0; k < 4; k++) {
for (i = 0; i < comps; i++) {
input[k + l * 4][i] = *lines[l]++;
}
}
}
/* Our solution here is to find the darkest and brightest colors in
* the 4x4 tile and use those as the two representative colors.
* There are probably better algorithms to use (histogram-based).
*/
for (k = 0; k < N_TEXELS; k++) {
int sum = 0;
for (i = 0; i < n_comp; i++) {
sum += input[k][i];
}
if (minSum > sum) {
minSum = sum;
minCol = k;
}
if (maxSum < sum) {
maxSum = sum;
maxCol = k;
}
if (input[k][ACOMP] < 128) {
transparent = 1;
}
}
color0 = COLOR565(input[minCol]);
color1 = COLOR565(input[maxCol]);
if (color0 == color1) {
/* we'll use 3-vector */
cc[0] = color0 | (color1 << 16);
hi = transparent ? -1 : 0;
} else {
if (transparent ^ (color0 <= color1)) {
int aux;
aux = color0;
color0 = color1;
color1 = aux;
aux = minCol;
minCol = maxCol;
maxCol = aux;
}
n_vect = (color0 <= color1) ? 2 : 3;
MAKEIVEC(n_vect, n_comp, iv, b, input[minCol], input[maxCol]);
/* add in texels */
cc[0] = color0 | (color1 << 16);
hi = 0;
for (k = N_TEXELS - 1; k >= 0; k--) {
int texel = 3;
if (input[k][ACOMP] >= 128) {
/* interpolate color */
CALCCDOT(texel, n_vect, n_comp, iv, b, input[k]);
texel = dxtn_color_tlat[transparent][texel];
}
/* add in texel */
hi <<= 2;
hi |= texel;
}
}
cc[1] = hi;
}
static void
dxt3_rgba_quantize (dword *cc, const byte *lines[], int comps)
{
float b, iv[MAX_COMP]; /* interpolation vector */
dword lolo, lohi; /* low quadword: lo dword, hi dword */
dword hihi; /* high quadword: high dword */
int color0, color1;
const int n_vect = 3;
const int n_comp = 3;
int minSum = 2000; /* big enough */
int maxSum = -1; /* small enough */
int minCol = 0; /* phoudoin: silent compiler! */
int maxCol = 0; /* phoudoin: silent compiler! */
byte input[N_TEXELS][MAX_COMP];
int i, k, l;
if (comps == 3) {
/* make the whole block opaque */
memset(input, -1, sizeof(input));
}
/* 4 texels each line */
for (l = 0; l < 4; l++) {
for (k = 0; k < 4; k++) {
for (i = 0; i < comps; i++) {
input[k + l * 4][i] = *lines[l]++;
}
}
}
/* Our solution here is to find the darkest and brightest colors in
* the 4x4 tile and use those as the two representative colors.
* There are probably better algorithms to use (histogram-based).
*/
for (k = 0; k < N_TEXELS; k++) {
int sum = 0;
for (i = 0; i < n_comp; i++) {
sum += input[k][i];
}
if (minSum > sum) {
minSum = sum;
minCol = k;
}
if (maxSum < sum) {
maxSum = sum;
maxCol = k;
}
}
/* add in alphas */
lolo = lohi = 0;
for (k = N_TEXELS - 1; k >= N_TEXELS / 2; k--) {
/* add in alpha */
lohi <<= 4;
lohi |= input[k][ACOMP] >> 4;
}
cc[1] = lohi;
for (; k >= 0; k--) {
/* add in alpha */
lolo <<= 4;
lolo |= input[k][ACOMP] >> 4;
}
cc[0] = lolo;
color0 = COLOR565(input[minCol]);
color1 = COLOR565(input[maxCol]);
cc[2] = color0 | (color1 << 16);
hihi = 0;
if (color0 != color1) {
MAKEIVEC(n_vect, n_comp, iv, b, input[minCol], input[maxCol]);
/* add in texels */
for (k = N_TEXELS - 1; k >= 0; k--) {
int texel;
/* interpolate color */
CALCCDOT(texel, n_vect, n_comp, iv, b, input[k]);
texel = dxtn_color_tlat[0][texel];
/* add in texel */
hihi <<= 2;
hihi |= texel;
}
}
cc[3] = hihi;
}
static void
dxt5_rgba_quantize (dword *cc, const byte *lines[], int comps)
{
float b, iv[MAX_COMP]; /* interpolation vector */
qword lo; /* low quadword */
dword hihi; /* high quadword: high dword */
int color0, color1;
const int n_vect = 3;
const int n_comp = 3;
int minSum = 2000; /* big enough */
int maxSum = -1; /* small enough */
int minCol = 0; /* phoudoin: silent compiler! */
int maxCol = 0; /* phoudoin: silent compiler! */
int alpha0 = 2000; /* big enough */
int alpha1 = -1; /* small enough */
int anyZero = 0, anyOne = 0;
int a_vect;
byte input[N_TEXELS][MAX_COMP];
int i, k, l;
if (comps == 3) {
/* make the whole block opaque */
memset(input, -1, sizeof(input));
}
/* 4 texels each line */
for (l = 0; l < 4; l++) {
for (k = 0; k < 4; k++) {
for (i = 0; i < comps; i++) {
input[k + l * 4][i] = *lines[l]++;
}
}
}
/* Our solution here is to find the darkest and brightest colors in
* the 4x4 tile and use those as the two representative colors.
* There are probably better algorithms to use (histogram-based).
*/
for (k = 0; k < N_TEXELS; k++) {
int sum = 0;
for (i = 0; i < n_comp; i++) {
sum += input[k][i];
}
if (minSum > sum) {
minSum = sum;
minCol = k;
}
if (maxSum < sum) {
maxSum = sum;
maxCol = k;
}
if (alpha0 > input[k][ACOMP]) {
alpha0 = input[k][ACOMP];
}
if (alpha1 < input[k][ACOMP]) {
alpha1 = input[k][ACOMP];
}
if (input[k][ACOMP] == 0) {
anyZero = 1;
}
if (input[k][ACOMP] == 255) {
anyOne = 1;
}
}
/* add in alphas */
if (alpha0 == alpha1) {
/* we'll use 6-vector */
cc[0] = alpha0 | (alpha1 << 8);
cc[1] = 0;
} else {
if (anyZero && ((alpha0 == 0) || (alpha1 == 0))) {
/* we still might use 8-vector */
anyZero = 0;
}
if (anyOne && ((alpha0 == 255) || (alpha1 == 255))) {
/* we still might use 8-vector */
anyOne = 0;
}
if ((anyZero | anyOne) ^ (alpha0 <= alpha1)) {
int aux;
aux = alpha0;
alpha0 = alpha1;
alpha1 = aux;
}
a_vect = (alpha0 <= alpha1) ? 5 : 7;
/* compute interpolation vector */
iv[ACOMP] = (float)a_vect / (alpha1 - alpha0);
b = -iv[ACOMP] * alpha0 + 0.5F;
/* add in alphas */
Q_MOV32(lo, 0);
for (k = N_TEXELS - 1; k >= 0; k--) {
int texel = -1;
if (anyZero | anyOne) {
if (input[k][ACOMP] == 0) {
texel = 6;
} else if (input[k][ACOMP] == 255) {
texel = 7;
}
}
/* interpolate alpha */
if (texel == -1) {
float dot = input[k][ACOMP] * iv[ACOMP];
texel = (int)(dot + b);
#if SAFECDOT
if (texel < 0) {
texel = 0;
} else if (texel > a_vect) {
texel = a_vect;
}
#endif
texel = dxtn_alpha_tlat[anyZero | anyOne][texel];
}
/* add in texel */
Q_SHL(lo, 3);
Q_OR32(lo, texel);
}
Q_SHL(lo, 16);
Q_OR32(lo, alpha0 | (alpha1 << 8));
((qword *)cc)[0] = lo;
}
color0 = COLOR565(input[minCol]);
color1 = COLOR565(input[maxCol]);
cc[2] = color0 | (color1 << 16);
hihi = 0;
if (color0 != color1) {
MAKEIVEC(n_vect, n_comp, iv, b, input[minCol], input[maxCol]);
/* add in texels */
for (k = N_TEXELS - 1; k >= 0; k--) {
int texel;
/* interpolate color */
CALCCDOT(texel, n_vect, n_comp, iv, b, input[k]);
texel = dxtn_color_tlat[0][texel];
/* add in texel */
hihi <<= 2;
hihi |= texel;
}
}
cc[3] = hihi;
}
#define ENCODER(dxtn, n) \
int TAPIENTRY \
dxtn##_encode (int width, int height, int comps, \
const void *source, int srcRowStride, \
void *dest, int destRowStride) \
{ \
int x, y; \
const byte *data; \
dword *encoded = (dword *)dest; \
void *newSource = NULL; \
\
/* Replicate image if width is not M4 or height is not M4 */ \
if ((width & 3) | (height & 3)) { \
int newWidth = (width + 3) & ~3; \
int newHeight = (height + 3) & ~3; \
newSource = malloc(comps * newWidth * newHeight * sizeof(byte *));\
_mesa_upscale_teximage2d(width, height, newWidth, newHeight, \
comps, (const byte *)source, \
srcRowStride, (byte *)newSource); \
source = newSource; \
width = newWidth; \
height = newHeight; \
srcRowStride = comps * newWidth; \
} \
\
data = (const byte *)source; \
destRowStride = (destRowStride - width * n) / 4; \
for (y = 0; y < height; y += 4) { \
unsigned int offs = 0 + (y + 0) * srcRowStride; \
for (x = 0; x < width; x += 4) { \
const byte *lines[4]; \
lines[0] = &data[offs]; \
lines[1] = lines[0] + srcRowStride; \
lines[2] = lines[1] + srcRowStride; \
lines[3] = lines[2] + srcRowStride; \
offs += 4 * comps; \
dxtn##_quantize(encoded, lines, comps); \
/* 4x4 block */ \
encoded += n; \
} \
encoded += destRowStride; \
} \
\
if (newSource != NULL) { \
free(newSource); \
} \
\
return 0; \
}
ENCODER(dxt1_rgb, 2)
ENCODER(dxt1_rgba, 2)
ENCODER(dxt3_rgba, 4)
ENCODER(dxt5_rgba, 4)
/***************************************************************************\
* DXTn decoder
*
* The decoder is based on GL_EXT_texture_compression_s3tc
* specification and serves as a concept for the encoder.
\***************************************************************************/
/* lookup table for scaling 4 bit colors up to 8 bits */
static const byte _rgb_scale_4[] = {
0, 17, 34, 51, 68, 85, 102, 119,
136, 153, 170, 187, 204, 221, 238, 255
};
/* lookup table for scaling 5 bit colors up to 8 bits */
static const byte _rgb_scale_5[] = {
0, 8, 16, 25, 33, 41, 49, 58,
66, 74, 82, 90, 99, 107, 115, 123,
132, 140, 148, 156, 165, 173, 181, 189,
197, 206, 214, 222, 230, 239, 247, 255
};
/* lookup table for scaling 6 bit colors up to 8 bits */
static const byte _rgb_scale_6[] = {
0, 4, 8, 12, 16, 20, 24, 28,
32, 36, 40, 45, 49, 53, 57, 61,
65, 69, 73, 77, 81, 85, 89, 93,
97, 101, 105, 109, 113, 117, 121, 125,
130, 134, 138, 142, 146, 150, 154, 158,
162, 166, 170, 174, 178, 182, 186, 190,
194, 198, 202, 206, 210, 215, 219, 223,
227, 231, 235, 239, 243, 247, 251, 255
};
#define CC_SEL(cc, which) (((dword *)(cc))[(which) / 32] >> ((which) & 31))
#define UP4(c) _rgb_scale_4[(c) & 15]
#define UP5(c) _rgb_scale_5[(c) & 31]
#define UP6(c) _rgb_scale_6[(c) & 63]
#define ZERO_4UBV(v) *((dword *)(v)) = 0
void TAPIENTRY
dxt1_rgb_decode_1 (const void *texture, int stride,
int i, int j, byte *rgba)
{
const byte *src = (const byte *)texture
+ ((j / 4) * ((stride + 3) / 4) + i / 4) * 8;
const int code = (src[4 + (j & 3)] >> ((i & 3) * 2)) & 0x3;
if (code == 0) {
rgba[RCOMP] = UP5(CC_SEL(src, 11));
rgba[GCOMP] = UP6(CC_SEL(src, 5));
rgba[BCOMP] = UP5(CC_SEL(src, 0));
} else if (code == 1) {
rgba[RCOMP] = UP5(CC_SEL(src, 27));
rgba[GCOMP] = UP6(CC_SEL(src, 21));
rgba[BCOMP] = UP5(CC_SEL(src, 16));
} else {
const word col0 = src[0] | (src[1] << 8);
const word col1 = src[2] | (src[3] << 8);
if (col0 > col1) {
if (code == 2) {
rgba[RCOMP] = (UP5(col0 >> 11) * 2 + UP5(col1 >> 11)) / 3;
rgba[GCOMP] = (UP6(col0 >> 5) * 2 + UP6(col1 >> 5)) / 3;
rgba[BCOMP] = (UP5(col0 ) * 2 + UP5(col1 )) / 3;
} else {
rgba[RCOMP] = (UP5(col0 >> 11) + 2 * UP5(col1 >> 11)) / 3;
rgba[GCOMP] = (UP6(col0 >> 5) + 2 * UP6(col1 >> 5)) / 3;
rgba[BCOMP] = (UP5(col0 ) + 2 * UP5(col1 )) / 3;
}
} else {
if (code == 2) {
rgba[RCOMP] = (UP5(col0 >> 11) + UP5(col1 >> 11)) / 2;
rgba[GCOMP] = (UP6(col0 >> 5) + UP6(col1 >> 5)) / 2;
rgba[BCOMP] = (UP5(col0 ) + UP5(col1 )) / 2;
} else {
ZERO_4UBV(rgba);
}
}
}
rgba[ACOMP] = 255;
}
void TAPIENTRY
dxt1_rgba_decode_1 (const void *texture, int stride,
int i, int j, byte *rgba)
{
/* Same as rgb_dxt1 above, except alpha=0 if col0<=col1 and code=3. */
const byte *src = (const byte *)texture
+ ((j / 4) * ((stride + 3) / 4) + i / 4) * 8;
const int code = (src[4 + (j & 3)] >> ((i & 3) * 2)) & 0x3;
if (code == 0) {
rgba[RCOMP] = UP5(CC_SEL(src, 11));
rgba[GCOMP] = UP6(CC_SEL(src, 5));
rgba[BCOMP] = UP5(CC_SEL(src, 0));
rgba[ACOMP] = 255;
} else if (code == 1) {
rgba[RCOMP] = UP5(CC_SEL(src, 27));
rgba[GCOMP] = UP6(CC_SEL(src, 21));
rgba[BCOMP] = UP5(CC_SEL(src, 16));
rgba[ACOMP] = 255;
} else {
const word col0 = src[0] | (src[1] << 8);
const word col1 = src[2] | (src[3] << 8);
if (col0 > col1) {
if (code == 2) {
rgba[RCOMP] = (UP5(col0 >> 11) * 2 + UP5(col1 >> 11)) / 3;
rgba[GCOMP] = (UP6(col0 >> 5) * 2 + UP6(col1 >> 5)) / 3;
rgba[BCOMP] = (UP5(col0 ) * 2 + UP5(col1 )) / 3;
} else {
rgba[RCOMP] = (UP5(col0 >> 11) + 2 * UP5(col1 >> 11)) / 3;
rgba[GCOMP] = (UP6(col0 >> 5) + 2 * UP6(col1 >> 5)) / 3;
rgba[BCOMP] = (UP5(col0 ) + 2 * UP5(col1 )) / 3;
}
rgba[ACOMP] = 255;
} else {
if (code == 2) {
rgba[RCOMP] = (UP5(col0 >> 11) + UP5(col1 >> 11)) / 2;
rgba[GCOMP] = (UP6(col0 >> 5) + UP6(col1 >> 5)) / 2;
rgba[BCOMP] = (UP5(col0 ) + UP5(col1 )) / 2;
rgba[ACOMP] = 255;
} else {
ZERO_4UBV(rgba);
}
}
}
}
void TAPIENTRY
dxt3_rgba_decode_1 (const void *texture, int stride,
int i, int j, byte *rgba)
{
const byte *src = (const byte *)texture
+ ((j / 4) * ((stride + 3) / 4) + i / 4) * 16;
const int code = (src[12 + (j & 3)] >> ((i & 3) * 2)) & 0x3;
const dword *cc = (const dword *)(src + 8);
if (code == 0) {
rgba[RCOMP] = UP5(CC_SEL(cc, 11));
rgba[GCOMP] = UP6(CC_SEL(cc, 5));
rgba[BCOMP] = UP5(CC_SEL(cc, 0));
} else if (code == 1) {
rgba[RCOMP] = UP5(CC_SEL(cc, 27));
rgba[GCOMP] = UP6(CC_SEL(cc, 21));
rgba[BCOMP] = UP5(CC_SEL(cc, 16));
} else if (code == 2) {
/* (col0 * (4 - code) + col1 * (code - 1)) / 3 */
rgba[RCOMP] = (UP5(CC_SEL(cc, 11)) * 2 + UP5(CC_SEL(cc, 27))) / 3;
rgba[GCOMP] = (UP6(CC_SEL(cc, 5)) * 2 + UP6(CC_SEL(cc, 21))) / 3;
rgba[BCOMP] = (UP5(CC_SEL(cc, 0)) * 2 + UP5(CC_SEL(cc, 16))) / 3;
} else {
rgba[RCOMP] = (UP5(CC_SEL(cc, 11)) + 2 * UP5(CC_SEL(cc, 27))) / 3;
rgba[GCOMP] = (UP6(CC_SEL(cc, 5)) + 2 * UP6(CC_SEL(cc, 21))) / 3;
rgba[BCOMP] = (UP5(CC_SEL(cc, 0)) + 2 * UP5(CC_SEL(cc, 16))) / 3;
}
rgba[ACOMP] = UP4(src[((j & 3) * 4 + (i & 3)) / 2] >> ((i & 1) * 4));
}
void TAPIENTRY
dxt5_rgba_decode_1 (const void *texture, int stride,
int i, int j, byte *rgba)
{
const byte *src = (const byte *)texture
+ ((j / 4) * ((stride + 3) / 4) + i / 4) * 16;
const int code = (src[12 + (j & 3)] >> ((i & 3) * 2)) & 0x3;
const dword *cc = (const dword *)(src + 8);
const byte alpha0 = src[0];
const byte alpha1 = src[1];
const int alphaShift = (((j & 3) * 4) + (i & 3)) * 3 + 16;
const int acode = ((alphaShift == 31)
? CC_SEL(src + 2, alphaShift - 16)
: CC_SEL(src, alphaShift)) & 0x7;
if (code == 0) {
rgba[RCOMP] = UP5(CC_SEL(cc, 11));
rgba[GCOMP] = UP6(CC_SEL(cc, 5));
rgba[BCOMP] = UP5(CC_SEL(cc, 0));
} else if (code == 1) {
rgba[RCOMP] = UP5(CC_SEL(cc, 27));
rgba[GCOMP] = UP6(CC_SEL(cc, 21));
rgba[BCOMP] = UP5(CC_SEL(cc, 16));
} else if (code == 2) {
/* (col0 * (4 - code) + col1 * (code - 1)) / 3 */
rgba[RCOMP] = (UP5(CC_SEL(cc, 11)) * 2 + UP5(CC_SEL(cc, 27))) / 3;
rgba[GCOMP] = (UP6(CC_SEL(cc, 5)) * 2 + UP6(CC_SEL(cc, 21))) / 3;
rgba[BCOMP] = (UP5(CC_SEL(cc, 0)) * 2 + UP5(CC_SEL(cc, 16))) / 3;
} else {
rgba[RCOMP] = (UP5(CC_SEL(cc, 11)) + 2 * UP5(CC_SEL(cc, 27))) / 3;
rgba[GCOMP] = (UP6(CC_SEL(cc, 5)) + 2 * UP6(CC_SEL(cc, 21))) / 3;
rgba[BCOMP] = (UP5(CC_SEL(cc, 0)) + 2 * UP5(CC_SEL(cc, 16))) / 3;
}
if (acode == 0) {
rgba[ACOMP] = alpha0;
} else if (acode == 1) {
rgba[ACOMP] = alpha1;
} else if (alpha0 > alpha1) {
rgba[ACOMP] = ((8 - acode) * alpha0 + (acode - 1) * alpha1) / 7;
} else if (acode == 6) {
rgba[ACOMP] = 0;
} else if (acode == 7) {
rgba[ACOMP] = 255;
} else {
rgba[ACOMP] = ((6 - acode) * alpha0 + (acode - 1) * alpha1) / 5;
}
}
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