diff options
Diffstat (limited to 'decompress.c')
| -rw-r--r-- | decompress.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/decompress.c b/decompress.c new file mode 100644 index 0000000..dae888d --- /dev/null +++ b/decompress.c @@ -0,0 +1,131 @@ +/* + +Not implemented yet + +Currently using zlib's decompress (sane) + + + + + +uint8_t getCM(uint8_t b){ + uint8_t r = b<<4; + return r>>4; +} + +uint8_t getCINFO(uint8_t b){ + return b>>4; +} + +bool validateCMFFLG(uint8_t CMF, uint8_t FLG){ + uint16_t CMFFLGcheck = (CMF<<8) + FLG; + return getCM(CMF) == 8 && CMFFLGcheck%31 == 0; +} + +typedef bool bit; + + +bool getBit(int n, int bit){ + return n & (1 << bit); +} + +void printBinary(uint8_t n){ + for(int i = 7; i >= 0; --i) + printf("%d", getBit(n, i)); +} + +uint8_t reverseBits(uint8_t n){ + uint8_t r = 0; + for(int i = 0; i < 8; ++i) + r |= ((bool)(n&(1<<(7-i))))<<i; + return r; +} + +uint8_t read8(bit *data, uint32_t *i){ + // This function is used for decompression + // The first bit is the LSB + uint8_t r = 0; + for(int j = 0; j < 8; ++j){ + r += data[(*i)+j]<<j; + } + (*i) += 8; + return r; +} + +uint16_t read16(bit *data, uint32_t *i){ + // This function is used for decompression + // The first bit is the LSB + uint16_t r = 0; + for(int j = 0; j < 16; ++j){ + r += data[(*i)+j]<<j; + } + (*i) += 16; + return r; +} + +typedef enum compressionType{ + NONE, FIXED, DYNAMIC, ERROR, +} compressionType; + +bit *decompressData(bit *data, uint32_t len){ + // we have to decompress with zlib + // in zlib the first bit is the least significant + // (b0 b1 b2 b3) + // ftp://ftp.isi.edu/in-notes/rfc1950.txt + // https://www.ietf.org/rfc/rfc1950.txt + // https://stackoverflow.com/questions/42934720/understanding-the-zlib-header-cmf-cm-cinfo-flg-fdict-dictid-flevel-rfc + + /*uint8_t CMF = data[0], FLG = data[1], FDICT, FLEVEL; + if(!validateCMFFLG(CMF, FLG)){ + fprintf(stderr, "Invalid CMF+FLG check\n"); + fclose(fp); + return 0; + } + uint32_t LZ77size = (1<<getCINFO(CMF))<<8; + FDICT = getBit(FLG, 5); + FLEVEL = getBit(FLG, 6) + (getBit(FLG, 7)<<1); + if(FDICT){ + fprintf(stderr, "I dont know how to deal with DICT\n"); + fclose(fp); + return 0; + } + + // Deflate data + // https://www.ietf.org/rfc/rfc1951.txt + /* + Data elements are packed into bytes in order of + increasing bit number within the byte, i.e., starting + with the least-significant bit of the byte. + Data elements other than Huffman codes are packed + starting with the least-significant bit of the data + element. + Huffman codes are packed starting with the most- + significant bit of the code. + * + / + + // Adler32 + bit *out = malloc(len); + bit BFINAL; + uint8_t BTYPE; + uint32_t ii = 0, oi = 0; + while(!BFINAL){ + BFINAL = data[ii++]; + if(BFINAL){ + // TODO: exit + } + BTYPE = (data[ii]<<1) + data[ii+1]; + ii += 2; + if(BTYPE == NONE){ + ii += 8-(ii%8); + } + uint16_t LEN, NLEN; + LEN = read16(data, &ii); + NLEN = read16(data, &ii); + + for(uint16_t j = 0; j < LEN; ++j){ + + } + } +} +*/
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