Function processDU

static/webuploader/webuploader.fis.js:6034–6084

(CDU, fdtbl, DC, HTDC, HTAC)

                }
    
                function processDU(CDU, fdtbl, DC, HTDC, HTAC){
                    var EOB = HTAC[0x00];
                    var M16zeroes = HTAC[0xF0];
                    var pos;
                    var I16 = 16;
                    var I63 = 63;
                    var I64 = 64;
                    var DU_DCT = fDCTQuant(CDU, fdtbl);
                    //ZigZag reorder
                    for (var j=0;j<I64;++j) {
                        DU[ZigZag[j]]=DU_DCT[j];
                    }
                    var Diff = DU[0] - DC; DC = DU[0];
                    //Encode DC
                    if (Diff==0) {
                        writeBits(HTDC[0]); // Diff might be 0
                    } else {
                        pos = 32767+Diff;
                        writeBits(HTDC[category[pos]]);
                        writeBits(bitcode[pos]);
                    }
                    //Encode ACs
                    var end0pos = 63; // was const... which is crazy
                    for (; (end0pos>0)&&(DU[end0pos]==0); end0pos--) {};
                    //end0pos = first element in reverse order !=0
                    if ( end0pos == 0) {
                        writeBits(EOB);
                        return DC;
                    }
                    var i = 1;
                    var lng;
                    while ( i <= end0pos ) {
                        var startpos = i;
                        for (; (DU[i]==0) && (i<=end0pos); ++i) {}
                        var nrzeroes = i-startpos;
                        if ( nrzeroes >= I16 ) {
                            lng = nrzeroes>>4;
                            for (var nrmarker=1; nrmarker <= lng; ++nrmarker)
                                writeBits(M16zeroes);
                            nrzeroes = nrzeroes&0xF;
                        }
                        pos = 32767+DU[i];
                        writeBits(HTAC[(nrzeroes<<4)+category[pos]]);
                        writeBits(bitcode[pos]);
                        i++;
                    }
                    if ( end0pos != I63 ) {
                        writeBits(EOB);
                    }
                    return DC;
                }
    
                function initCharLookupTable(){
                    var sfcc = String.fromCharCode;