/* If dest is NULL, return uncompressed length in *destLen. */
int tinf_gzip_uncompress(void *dest, unsigned int *destLen,
const void *source, unsigned int sourceLen)
{
unsigned char *src = (unsigned char *)source;
unsigned char *dst = (unsigned char *)dest;
unsigned char *start;
unsigned int dlen, crc32;
int res;
unsigned char flg;
/* -- check format -- */
/* check id bytes */
if (src[0] != 0x1f || src[1] != 0x8b) return TINF_DATA_ERROR;
/* check method is deflate */
if (src[2] != 8) return TINF_DATA_ERROR;
/* get flag byte */
flg = src[3];
/* check that reserved bits are zero */
if (flg & 0xe0) return TINF_DATA_ERROR;
/* -- find start of compressed data -- */
/* skip base header of 10 bytes */
start = src + 10;
/* skip extra data if present */
if (flg & FEXTRA)
{
unsigned int xlen = start[1];
xlen = 256*xlen + start[0];
start += xlen + 2;
}
/* skip file name if present */
if (flg & FNAME) { while (*start) ++start; ++start; }
/* skip file comment if present */
if (flg & FCOMMENT) { while (*start) ++start; ++start; }
/* check header crc if present */
if (flg & FHCRC)
{
unsigned int hcrc = start[1];
hcrc = 256*hcrc + start[0];
if (hcrc != (tinf_crc32(src, start - src) & 0x0000ffff))
return TINF_DATA_ERROR;
start += 2;
}
/* -- get decompressed length -- */
dlen = src[sourceLen - 1];
dlen = 256*dlen + src[sourceLen - 2];
dlen = 256*dlen + src[sourceLen - 3];
dlen = 256*dlen + src[sourceLen - 4];
if (!dst) {
*destLen = dlen;
return TINF_OK;
}
/* -- get crc32 of decompressed data -- */
crc32 = src[sourceLen - 5];
crc32 = 256*crc32 + src[sourceLen - 6];
crc32 = 256*crc32 + src[sourceLen - 7];
crc32 = 256*crc32 + src[sourceLen - 8];
/* -- decompress data -- */
res = tinf_uncompress(dst, destLen, start, src + sourceLen - start - 8);
if (res != TINF_OK) return TINF_DATA_ERROR;
if (*destLen != dlen) return TINF_DATA_ERROR;
/* -- check CRC32 checksum -- */
if (crc32 != tinf_crc32(dst, dlen)) return TINF_DATA_ERROR;
return TINF_OK;
}
bool CEL_CHUNK::readCompressedPixels(std::ifstream & s, PIXELTYPE pixelFormat, DWORD sourceLen) {
bool result = s & width && s & height;
if (!result) {
return result;
}
DWORD dim = width * height;
pixels.resize(dim);
sourceLen -= 4; /* width, height */
std::vector<BYTE> source(sourceLen);
s.read((char*) source.data() /*zlib header*/, sourceLen);
result = s.good();
if (!result) {
return result;
}
DWORD expectedLen = dim;
switch (pixelFormat) {
case INDEXED: {
break;
}
case GRAYSCALE: {
expectedLen *= 2;
break;
}
case RGBA: {
expectedLen *= 4;
break;
}
default:
result = false;
}
std::vector<BYTE> uncompressed(expectedLen);
DWORD destLen;
auto outcome = tinf_uncompress(uncompressed.data(), &destLen, source.data() + 2, sourceLen - 2 - 4/*zlib header, crc*/);
result = result && TINF_OK == outcome;
result = result && destLen == expectedLen;
if (!result)
return result;
switch (pixelFormat) {
case INDEXED: {
for (DWORD i = 0; i < dim; i++) {
pixels[i].INDEXED = uncompressed[i];
}
break;
}
case GRAYSCALE: {
for (DWORD i = 0; i < dim; i++) {
pixels[i].GRAYSCALE[0] = uncompressed[2 * i];
pixels[i].GRAYSCALE[1] = uncompressed[2 * i + 1];
}
break;
}
case RGBA: {
for (DWORD i = 0; i < dim; i++) {
pixels[i].RGBA[0] = uncompressed[4 * i];
pixels[i].RGBA[1] = uncompressed[4 * i + 1];
pixels[i].RGBA[2] = uncompressed[4 * i + 2];
pixels[i].RGBA[3] = uncompressed[4 * i + 3];
}
break;
}
}
return result;
}
