sdds.cpp

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#include <stdlib.h>
#include "gldrv/sdds.h"

#ifndef GETL16
#define GETL16( buf ) ( ( (unsigned short) (buf)[0] )|( (unsigned short) (buf)[1]<<8 ) )
#endif
#ifndef GETL64
#define GETL64( buf )                 \
    ( ( (unsigned int) (buf)[0] )     \
     |( (unsigned long long) (buf)[1] \
       <<8 )                          \
     |( (unsigned long long) (buf)[2] \
       <<16 )                         \
     |( (unsigned long long) (buf)[3] \
       <<24 )                         \
     |( (unsigned long long) (buf)[4] \
       <<32 )                         \
     |( (unsigned long long) (buf)[5] \
       <<40 )|( (unsigned long long) (buf)[6]<<48 )|( (unsigned long long) (buf)[7]<<56 ) )
#endif

/*  Software decompression for DDS files, helper functions */

void decode_color_block( unsigned char *dst, unsigned char *src, int w, int h, int rowbytes, TEXTUREFORMAT format )
{
    int i, x, y;
    unsigned int   indexes, idx;
    unsigned char *d;
    unsigned char  colors[4][3];
    unsigned short c0, c1;
    c0 = GETL16( &src[0] );
    c1 = GETL16( &src[2] );
    colors[0][0] = ( (c0>>11)&0x1f )<<3;
    colors[0][1] = ( (c0>>5)&0x3f )<<2;
    colors[0][2] = ( (c0)&0x1f )<<3;
    colors[1][0] = ( (c1>>11)&0x1f )<<3;
    colors[1][1] = ( (c1>>5)&0x3f )<<2;
    colors[1][2] = ( (c1)&0x1f )<<3;
    if ( (c0 > c1) || (format == DXT5) ) {
        for (i = 0; i < 3; ++i) {
            colors[2][i] = (2*colors[0][i]+colors[1][i]+1)/3;
            colors[3][i] = (2*colors[1][i]+colors[0][i]+1)/3;
        }
    } else {
        for (i = 0; i < 3; ++i) {
            colors[2][i] = (colors[0][i]+colors[1][i]+1)>>1;
            colors[3][i] = 255;
        }
    }
    src += 4;
    for (y = 0; y < h; ++y) {
        d = dst+(y*rowbytes);
        indexes = src[y];
        for (x = 0; x < w; ++x) {
            idx       = indexes&0x03;
            d[0]      = colors[idx][0];
            d[1]      = colors[idx][1];
            d[2]      = colors[idx][2];
            if (format == DXT1 || format == DXT1RGBA)
                d[3] = ( (c0 <= c1) && idx == 3 ) ? 0 : 255;
            indexes >>= 2;
            d += 4;
        }
    }
}

void decode_dxt3_alpha( unsigned char *dst, unsigned char *src, int w, int h, int rowbytes )
{
    int x, y;
    unsigned char *d;
    unsigned int   bits;
    for (y = 0; y < h; ++y) {
        d    = dst+(y*rowbytes);
        bits = GETL16( &src[2*y] );
        bits = GETL16( &src[2*y] );
        for (x = 0; x < w; ++x) {
            d[0]   = (bits&0x0f)*17;
            bits >>= 4;
            d     += 4;
        }
    }
}

void decode_dxt5_alpha( unsigned char *dst, unsigned char *src, int w, int h, int bpp, int rowbytes )
{
    int x, y, code;
    unsigned char     *d, a0 = src[0], a1 = src[1];
    unsigned long long bits = GETL64( src )>>16;
    for (y = 0; y < h; ++y) {
        d = dst+(y*rowbytes);
        for (x = 0; x < w; ++x) {
            code = ( (unsigned int) bits )&0x07;
            if (code == 0)
                d[0] = a0;
            else if (code == 1)
                d[0] = a1;
            else if (a0 > a1)
                d[0] = ( (8-code)*a0+(code-1)*a1 )/7;
            else if (code >= 6)
                d[0] = (code == 6) ? 0 : 255;
            else
                d[0] = ( (6-code)*a0+(code-1)*a1 )/5;
            bits >>= 3;
            d     += bpp;
        }
        if (w < 4)
            bits >>= ( 3*(4-w) );
    }
}

void ddsDecompress( unsigned char* &buffer, unsigned char* &data, TEXTUREFORMAT internformat, int height, int width )
{
    unsigned char *pos_out = NULL, *pos_in = NULL;
    int bpp = 4;
    unsigned int   sx, sy;

    sx      = (width < 4) ? width : 4;
    sy      = (height < 4) ? width : 4;
    data    = (unsigned char*) malloc( height*width*bpp );
    pos_out = data;
    pos_in  = buffer;
    for (int y = 0; y < height; y += 4)
        for (int x = 0; x < width; x += 4) {
            pos_out = data+(y*width+x)*bpp;
            if (internformat == DXT3) {
                decode_dxt3_alpha( pos_out+3, pos_in, sx, sy, width*bpp );
                pos_in += 8;
            } else if (internformat == DXT5) {
                decode_dxt5_alpha( pos_out+3, pos_in, sx, sy, bpp, width*bpp );
                pos_in += 8;
            }
            decode_color_block( pos_out, pos_in, sx, sy, width*bpp, internformat );
            pos_in += 8;
        }
}

/*  END of software decompression for DDS helper functions */