decompress.js

Iuppiter.decompress = function(sstart, slen, dstart) 
{
    slen = slen | 0;

    var 
        src = 0, 
        dst = 0,
        cpy = 0, 
        copymap = 0,
        copymask = 1 << (NBBY - 1 | 0),
        mlen = 0, 
        offset = 0;

    //var avg_mlen = [];
        
    while (src < slen) 
    {
        if ((copymask <<= 1) === (1 << NBBY)) 
        {
            copymask = 1;
            copymap = sstart[src];
            src = src + 1 | 0;
        }

        if (copymap & copymask) 
        {
            mlen = (sstart[src] >> (NBBY - MATCH_BITS | 0)) + MATCH_MIN | 0;
            offset = ((sstart[src] << NBBY) | sstart[src + 1 | 0]) & OFFSET_MASK;
            src = src + 2 | 0;

            cpy = dst - offset | 0;
            //if (cpy >= 0)
            {
                //console.log(mlen);
                //avg_mlen.push(mlen);

                //dstart.set(dstart.subarray(cpy, cpy + mlen | 0), dst);
                //dst = dst + mlen | 0;
                //cpy = cpy + mlen | 0;

                //mlen = mlen - 1 | 0;
                while (mlen > 4)
                {
                    dstart[dst] = dstart[cpy];
                    dst = dst + 1 | 0;
                    cpy = cpy + 1 | 0;

                    dstart[dst] = dstart[cpy];
                    dst = dst + 1 | 0;
                    cpy = cpy + 1 | 0;

                    dstart[dst] = dstart[cpy];
                    dst = dst + 1 | 0;
                    cpy = cpy + 1 | 0;

                    dstart[dst] = dstart[cpy];
                    dst = dst + 1 | 0;
                    cpy = cpy + 1 | 0;

                    mlen = mlen - 4 | 0;
                }

                while (mlen > 0)
                {
                    dstart[dst] = dstart[cpy];
                    dst = dst + 1 | 0;
                    cpy = cpy + 1 | 0;
                    mlen = mlen - 1 | 0;
                }
            }
            //else
            //{
            //    /*
            //     * offset before start of destination buffer
            //     * indicates corrupt source data
            //     */
            //    console.warn("possibly corrupt data");
            //    return dstart;
            //}
        } 
        else 
        {
            dstart[dst] = sstart[src];
            dst = dst + 1 | 0;
            src = src + 1 | 0;
        }
    }

    //console.log(avg_mlen.reduce(function(a, x) { return a + x; }, 0) / avg_mlen.length);
    
    //console.assert(dstart.length >= dst);
    //console.assert(sstart.length >= src);

    return dstart;
};