Texas Instruments TMS320C64X Programmer's Reference Manual page 144

DSP_fft16x16t
xl0_1 = x_2 − x_6;
n00 = xh0_0 + xh0_1; n01 = xh1_0 + xh1_1;
n10 = xl0_0 + xl1_1; n11 = xl1_0 − xl0_1;
n20 = xh0_0 − xh0_1; n21 = xh1_0 − xh1_1;
n30 = xl0_0 − xl1_1; n31 = xl1_0 + xl0_1;
if (radix == 2)
{
/*−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−*/
/* Perform DSP_radix2 style decomposition.
/*−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−*/
n00 = x_0 + x_2;
n20 = x_0 − x_2;
n10 = x_4 + x_6;
n30 = x_4 − x_6;
}
y0[2*h2] = n00;
y1[2*h2] = n10;
y2[2*h2] = n20;
y3[2*h2] = n30;
/*−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−*/
/* Read in the next eight inputs, and perform radix4 or DSP_radix2*/
/* decomposition.
/*−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−*/
x_8 = x2[0];
x_a = x2[2];
x_c = x2[4];
x_e = x2[6];
x2 += 8;
xh0_2 = x_8 + x_c;
xl0_2 = x_8 − x_c;
xh0_3 = x_a + x_e;
xl0_3 = x_a − x_e;
n02 = xh0_2 + xh0_3;
n12 = xl0_2 + xl1_3;
n22 = xh0_2 − xh0_3;
n32 = xl0_2 − xl1_3;
4-116
xl1_1 = x_3 − x_7;
n01 = x_1 + x_3;
n21 = x_1 − x_3;
n11 = x_5 + x_7;
n31 = x_5 − x_7;
y0[2*h2 + 1] = n01;
y1[2*h2 + 1] = n11;
y2[2*h2 + 1] = n21;
y3[2*h2 + 1] = n31;
x_9 = x2[1];
x_b = x2[3];
x_d = x2[5];
x_f = x2[7];
xh1_2 = x_9 + x_d;
xl1_2 = x_9 − x_d;
xh1_3 = x_b + x_f;
xl1_3 = x_b − x_f;
n03 = xh1_2 + xh1_3;
n13 = xl1_2 − xl0_3;
n23 = xh1_2 − xh1_3;
n33 = xl1_2 + xl0_3;
*/
*/