Texas Instruments TMS320C67 DSP Series Programmer's Reference Manual page 55

DSPF_sp_ifftSPxSP
4-30
else
break;
l0=l0-17;
if (radix <= 4) for (i = 0; i < n; i += 4)
{
/* reversal computation */
j0 = (j
j1 = (j >> 6);
k0 = brev[j0];
k1 = brev[j1];
k = (k0 << 6) +
k = k >> l0;
j++;
x0 = ptr_x0[0];
x2 = ptr_x0[2];
x4 = ptr_x0[4];
x6 = ptr_x0[6];
ptr_x0 += 8;
xh0_0 = x0 + x4;
xh1_0 = x1 + x5;
xh0_1 = x2 + x6;
xh1_1 = x3 + x7;
if (radix == 2)
{
xh0_0 = x0;
xh1_0 = x1;
xh0_1 = x2;
xh1_1 = x3;
}
yt0 = xh0_0 + xh0_1;
yt1 = xh1_0 + xh1_1;
yt4 = xh0_0 - xh0_1;
yt5 = xh1_0 - xh1_1;
xl0_0 = x0 - x4;
xl1_0 = x1 - x5;
xl0_1 = x2 - x6;
) & 0x3F;
k1;
/* multiple of 4 index */
x1 = ptr_x0[1];
x3 = ptr_x0[3];
x5 = ptr_x0[5];
x7 = ptr_x0[7];