Texas Instruments TMS320C64X User Manual

Page 47

DSP_fft16x16r

4-19

C64x+ DSPLIB Reference

x_1 = x[1];

x_h2 = x[h2];

x_h2p1 = x[h2+1];

x_l1 = x[l1];

x_l1p1 = x[l1+1];

x_l2 = x[l2];

x_l2p1 = x[l2+1];

xh0 = x_0 + x_l1;

xh1 = x_1 + x_l1p1;

xl0 = x_0 − x_l1;

xl1 = x_1 − x_l1p1;

xh20 = x_h2 + x_l2;

xh21 = x_h2p1 + x_l2p1;

xl20 = x_h2 − x_l2;

xl21 = x_h2p1 − x_l2p1;

ptr_x0 = x;

ptr_x0[0] = ((short)(xh0 + xh20))>>1;

ptr_x0[1] = ((short)(xh1 + xh21))>>1;

ptr_x2 = ptr_x0;

x += 2;

predj = (j − fft_jmp);

if (!predj) x += fft_jmp;

if (!predj) j = 0;

xt0 = xh0 − xh20;

yt0 = xh1 − xh21;

xt1 = xl0 + xl21;

yt2 = xl1 + xl20;

xt2 = xl0 − xl21;

yt1 = xl1 − xl20;

l1p1 = l1+1;

h2p1 = h2+1;

l2p1 = l2+1;

ptr_x2[l1 ] = (xt1 * co1 + yt1 * si1 + 0x00008000) >> 16;

ptr_x2[l1p1] = (yt1 * co1 − xt1 * si1 + 0x00008000) >> 16;

ptr_x2[h2 ] = (xt0 * co2 + yt0 * si2 + 0x00008000) >> 16;