idctqtab
idctqtab(quant[dscans[0].tq], decdata->dquant[0]);
idctqtab(quant[dscans[1].tq], decdata->dquant[1]);
idctqtab(quant[dscans[2].tq], decdata->dquant[2]);
static void idctqtab __P((unsigned char *, PREC *));