Texas Instruments TMS320C64X - Manual (Page 63)

DSP_ifft16x32
4-35 C64x+ DSPLIB Reference
- The FFT coefficients (twiddle factors) are generated using the program
tw_fft16x32 provided in the directory ‘support\fft’. The scale factor must be
32767.5. No scaling is done with the function; thus the input data must be
scaled by 2
log2(nx) to completely prevent overflow.
Implementation Notes
- Bank Conflicts: No bank conflicts occur.
- Interruptibility: The code is interruptible.
- The routine uses log
4
(nx) − 1 stages of radix-4 transform and performs
either a radix-2 or radix-4 transform on the last stage depending on nx. If
nx is a power of 4, then this last stage is also a radix-4 transform, otherwise
it is a radix-2 transform.
- See the fft16x16t implementation notes, as similar ideas are used.
Benchmarks Cycles (12.5 * nx/8 + 30) * ceil[log
4
(nx) − 1] + 6 * nx/4 + 32
Codesize 864 bytes