DSP_ifft32x32
4-37 C64x+ DSPLIB Reference
-
The FFT coefficients (twiddle factors) are generated using the program
tw_fft32x32 provided in the directory ‘support\fft’. The scale factor must be
2147483647.5. 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 (13*nx/8 + 28) * ceil(log
4
(nx) − 1) + 6 * nx/4 + 39
Codesize 960 bytes