DarkflameServer/dCommon/ZCompression.cpp

#include "ZCompression.h"

#include <zlib.h>

namespace ZCompression
{
    int32_t GetMaxCompressedLength(int32_t nLenSrc)
    {
        int32_t n16kBlocks = (nLenSrc + 16383) / 16384; // round up any fraction of a block
        return (nLenSrc + 6 + (n16kBlocks * 5));
    }

    int32_t Compress(const uint8_t* abSrc, int32_t nLenSrc, uint8_t* abDst, int32_t nLenDst)
    {
        z_stream zInfo = { 0 };
        zInfo.total_in = zInfo.avail_in = nLenSrc;
        zInfo.total_out = zInfo.avail_out = nLenDst;
        zInfo.next_in = const_cast<Bytef*>(abSrc);
        zInfo.next_out = abDst;

        int nErr, nRet = -1;
        nErr = deflateInit(&zInfo, Z_DEFAULT_COMPRESSION); // zlib function
        if (nErr == Z_OK) {
            nErr = deflate(&zInfo, Z_FINISH);              // zlib function
            if (nErr == Z_STREAM_END) {
                nRet = zInfo.total_out;
            }
        }
        deflateEnd(&zInfo);    // zlib function
        return(nRet);

    }

    int32_t Decompress(const uint8_t* abSrc, int32_t nLenSrc, uint8_t* abDst, int32_t nLenDst, int32_t& nErr)
    {
        // Get the size of the decompressed data
        z_stream zInfo = { 0 };
        zInfo.total_in = zInfo.avail_in = nLenSrc;
        zInfo.total_out = zInfo.avail_out = nLenDst;
        zInfo.next_in = const_cast<Bytef*>(abSrc);
        zInfo.next_out = abDst;

        int nRet = -1;
        nErr = inflateInit(&zInfo); // zlib function
        if (nErr == Z_OK) {
            nErr = inflate(&zInfo, Z_FINISH); // zlib function
            if (nErr == Z_STREAM_END) {
                nRet = zInfo.total_out;
            }
        }
        inflateEnd(&zInfo); // zlib function
        return(nRet);
        
        /*
        z_stream zInfo = { 0 };
        zInfo.total_in = zInfo.avail_in = nLenSrc;
        zInfo.total_out = zInfo.avail_out = nLenDst;
        zInfo.next_in = const_cast<Bytef*>(abSrc);
        zInfo.next_out = const_cast<Bytef*>(abDst);

        int nRet = -1;
        nErr = inflateInit(&zInfo);               // zlib function
        if (nErr == Z_OK) {
            nErr = inflate(&zInfo, Z_FINISH);     // zlib function
            if (nErr == Z_STREAM_END) {
                nRet = zInfo.total_out;
            }
        }
        inflateEnd(&zInfo);   // zlib function
        return(nRet); // -1 or len of output
        */
    }
}