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Add feature to replace abs/fabs and memset with your own.

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This commit is contained in:
Kevin Schmidt 2017-04-18 18:28:02 +02:00
parent c7110588a4
commit 9b3358fec1
1 changed files with 22 additions and 7 deletions
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29
stb_dxt.h
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@ -61,8 +61,23 @@ void stb_compress_bc5_block(unsigned char *dest, const unsigned char *src_rg_two
// #define STB_DXT_USE_ROUNDING_BIAS
#include <stdlib.h>
#if !defined(STBD_ABS) || !defined(STBI_FABS)
#include <math.h>
#include <string.h> // memset
#endif
#ifndef STBD_ABS
#define STBD_ABS(i) abs(i)
#endif
#ifndef STBD_FABS
#define STBD_FABS(x) fabs(x)
#endif
#ifndef STBD_MEMSET
#include <string.h>
#define STBD_MEMSET(x) memset(x)
#endif
static unsigned char stb__Expand5[32];
static unsigned char stb__Expand6[64];
@ -127,13 +142,13 @@ static void stb__PrepareOptTable(unsigned char *Table,const unsigned char *expan
for (mx=0;mx<size;mx++) {
int mine = expand[mn];
int maxe = expand[mx];
int err = abs(stb__Lerp13(maxe, mine) - i);
int err = STBD_ABS(stb__Lerp13(maxe, mine) - i);
// DX10 spec says that interpolation must be within 3% of "correct" result,
// add this as error term. (normally we'd expect a random distribution of
// +-1.5% error, but nowhere in the spec does it say that the error has to be
// unbiased - better safe than sorry).
err += abs(maxe - mine) * 3 / 100;
err += STBD_ABS(maxe - mine) * 3 / 100;
if(err < bestErr)
{
@ -165,7 +180,7 @@ static void stb__DitherBlock(unsigned char *dest, unsigned char *block)
for (ch=0; ch<3; ++ch) {
unsigned char *bp = block+ch, *dp = dest+ch;
unsigned char *quant = (ch == 1) ? stb__QuantGTab+8 : stb__QuantRBTab+8;
memset(err, 0, sizeof(err));
STBD_MEMSET(err, 0, sizeof(err));
for(y=0; y<4; ++y) {
dp[ 0] = quant[bp[ 0] + ((3*ep2[1] + 5*ep2[0]) >> 4)];
ep1[0] = bp[ 0] - dp[ 0];
@ -349,9 +364,9 @@ static void stb__OptimizeColorsBlock(unsigned char *block, unsigned short *pmax1
vfb = b;
}
magn = fabs(vfr);
if (fabs(vfg) > magn) magn = fabs(vfg);
if (fabs(vfb) > magn) magn = fabs(vfb);
magn = STBD_FABS(vfr);
if (STBD_FABS(vfg) > magn) magn = STBD_FABS(vfg);
if (STBD_FABS(vfb) > magn) magn = STBD_FABS(vfb);
if(magn < 4.0f) { // too small, default to luminance
v_r = 299; // JPEG YCbCr luma coefs, scaled by 1000.