C++ (Cpp) BitStream::read_bytes Examples

Example #1

File: Compressor.cpp Project: bosorioo/Data-Compression

std::vector<unsigned char> Compressor::decompress(void* data, unsigned length)
{
    BitStream bs;
    bs.insert(data, length);
    bs.read_bytes(&length, 3);

    if (!mIsLittleEndian)
        length = (unsigned)reverseEndianess((int)length);

    unsigned char bits;
    bs.read_bits(bits, 3);

    if (bits < 1 || bits > 7)
    {
        char bStr[4];
        throw (std::string("Bit-size of enconding isn't valid: ") + std::string(itoa(bits, bStr, 10)));
    }

    unsigned char byte;
    int bitsRead = 27;
    int i;
    std::vector<char> charTable;
    std::vector<char> compressedChars;

    for (i = 1; i <= (1 << bits) - 1; i++)
    {
        bs.read_bits(byte, 8);
        charTable.push_back(byte);
        bitsRead += 8;

        if (!bs.canRead())
            throw std::string ("Bad file for decompression [1]");
    }

    for (unsigned j = 1; j <= length; j++)
    {
        bs.read_bits(byte, bits);
        bitsRead += bits;
        compressedChars.push_back(byte);

        if (!bs.canRead())
            throw std::string ("Bad file for decompression [2]");
    }

    std::vector<unsigned char> result(length, 0);

    for (i = 0; i < (int)compressedChars.size(); i++)
    {
        if (compressedChars[i] == 0 || (unsigned char)compressedChars[i] > charTable.size())
        {
            if (!bs.canRead())
                throw std::string ("Bad file for decompression [3]");

            bs.read_bits(result[i], 8);
            bitsRead += 8;
        }
        else
        {
            result[i] = charTable[compressedChars[i] - 1];
        }
    }

    return result;
}