/*
 * Compress3.cpp
 * Copyright 1999-2000 Y.Takagi. All Rights Reserved.
 */


// #define DBG_CON_STREAM

#ifdef DBG_CON_STREAM
#include <fstream>
using namespace std;
#endif

#include "Compress3.h"

#define PACK_TYPE       2


int
compress3(unsigned char* pOut, unsigned char* pIn, int n)
{
        int count;
        int count_byte;
        unsigned char* pBase;
        unsigned char* pLast;
        unsigned char keep;

        count = 0;
        count_byte = 0;

        keep   = ~(*pIn);
        pLast  = pIn + n;

        for (pBase = pIn; (pBase < pLast) && (count_byte < n) ; pBase++) {
                if (*pBase == keep) {
                        if (count < 0xff + PACK_TYPE) {
                                count++;
                        } else {
                                *pOut++ = keep;
                                *pOut++ = count - PACK_TYPE;
                                count = 1;
                                keep  = *pOut++ = *pBase;
                                count_byte += 3;
                        }
                } else {
                        if (count > 1) {
                                *pOut++ = keep;
                                *pOut++ = count - PACK_TYPE;
                                count_byte += 2;
                        }
                        count = 1;
                        keep  = *pOut++ = *pBase;
                        count_byte++;
                }
        }

        if (count > 1) {
                if ((count_byte + 2) < n) {
                        *pOut++ = keep;
                        *pOut++ = count - PACK_TYPE;
                        count_byte += 2;
                } else
                        count_byte = n;
        }

        return count_byte;
}


#ifdef DBG_CON_STREAM

int
main(int argc, char **argv)
{
        if (argc < 2)
                return -1;

        ifstream ifs(*++argv, ios::binary | ios::nocreate);
        if (!ifs)
                return -1;

        ifs.seekg(0, ios::end);
        long size = ifs.tellg();
        ifs.seekg(0, ios::beg);

        unsigned char* pIn  = new unsigned char[size];
        unsigned char* pOut = new unsigned char[size * 3];

        ifs.read(pIn, size);

        int cnt = PackBits(pOut, pIn, size);

        ofstream ofs("test.bin", ios::binary);
        ofs.write(pOut, cnt);

        delete [] pIn;
        delete [] pOut;

}

#endif