Texas Instruments TMS320C64X Programmer's Reference Manual page 49

k = (k0 << 6) | k1;
if (l0 < 0)
k = k << −l0;
else
k = k >> l0;
j++; /* multiple of 4 index */
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;
xl1_1 = x3 − x7;
if (radix == 2)
{
xl0_0 = x4;
xl1_0 = x5;
x1 = ptr_x0[1];
x3 = ptr_x0[3];
x5 = ptr_x0[5];
x7 = ptr_x0[7];
DSP_fft16x16r
C64x+ DSPLIB Reference 4-21