lastDC = lastDC + diff;
lastDC += diff;
void decodeDCCoefficient(int[] dataUnit, int iComp, boolean first, int approxBit) {	int[] sParams = scanHeader.componentParameters[componentIds[iComp]];	JPEGHuffmanTable dcTable = dcHuffmanTables[sParams[DC]];	int lastDC = 0;	if (progressive && !first) {		int bit = nextBit();		lastDC = dataUnit[0] + (bit << approxBit);	} else {		lastDC = precedingDCs[iComp];		int nBits = decodeUsingTable(dcTable);		if (nBits != 0) {			int bits = receive(nBits);			int diff = extendBy(bits, nBits);			lastDC = lastDC + diff;			precedingDCs[iComp] = lastDC;		}		if (progressive) {			lastDC = lastDC << approxBit;		}	}	dataUnit[0] = lastDC;}