dif2.dsp

来自「平台：ADSP21xx 编程语言：ASM 说明：ADSP21xx-离散余弦变」· DSP 代码 · 共 33 行

.module/ram do_DIF2;        {*** 8 2-way DIFs ***}
.external tmp;
.entry DIF2;

DIF2:
        i0=^tmp;
        i1=^tmp+1;
        i2=^tmp;
        i3=^tmp+1;
        m0=2;

        ax1=dm(i3,m0);
        af=pass ax1, ax0=dm(i2,m0);
        ar=ax0+af, ax1=dm(i3,m0), my0=pm(i6,m6);
        ar=ax0-af, dm(i0,m0)=ar;
        mr=ar*my0(ss);
        
        cntr=6;
        do difx2 until ce;
                af=pass ax1, ax0=dm(i2,m0);
                ar=ax0+af, ax1=dm(i3,m0);
                ar=ax0-af, dm(i0,m0)=ar;
        difx2:  mr=ar*my0(ss), dm(i1,m0)=mr1;

        af=pass ax1, ax0=dm(i2,m0);
        ar=ax0+af;
        ar=ax0-af, dm(i0,m0)=ar;
        mr=ar*my0(ss), dm(i1,m0)=mr1;

        dm(i1,m1)=mr1;
        rts;                                       {*** end 8 2-way DIFs ***}
.endmod;