Other Parts Discussed in Thread: TMS320C6747, OMAP-L137, CCSTUDIO
Hello
i have downloaded the DSP-lib ( http://focus.ti.com/docs/toolsw/folders/print/sprc121.html ) to use it with the DSP-Side of the OMAP-L137/TMS320C6747.
I would like to perform a fft and a ifft, to echo back the result of the ifft to prove everything worked well. Unfortunately my version does not provide a documentation or working examples, so i have a few questions that probably could be solved here.
1)
because the twiddle-factors are generated seperate and only once i would like to use the following function
void DSPF_sp_fftSPxSP
(
int N,
float * ptr_x,
float * ptr_w,
float * ptr_y,
unsigned char * brev,
int n_min,
int offset,
int n_max
);
Unfortunately i can not find any information on what brev is supposed to point, it should be an area containing 64 Chars that contain the information on how to switch the different input-Information due to the butterfly-algorithm. But i am not shure how this information would have to look like, to work with the algorithm.
2)
in the directory C:\CCStudio\c6700\dsplib\support\fft there is a file tw_fftSPxSP_C67.c, wich shows (as far as i understood this) the source code to generate the twiddle-factors for the FFT. In the source files in the directory C:\CCStudio\c6700\dsplib\lib within the comments for the apropriate FFT-function, there is also such a function mentioned. Unfortunately they differ from each other and do not result in the same twiddle-factors beeing calculated.
in the C:\CCStudio\c6700\dsplib\bin - directory of the DSP-Lib are some command-driven programs, calculating the twiddle-factors for the different FFT-versions. i ran tw_fftSPxSP_c67.exe and the resulting twiddle factors differ from the two other possible twiddle-factor-vectors (mentioned in the paragraph above).
So, can you provide me with the information, wich of the 3 information-sources offers the right twiddle factors? (i would also be interested in the source code, to run it myself if the command-driven-program would be the right one)
