is there any limitation in optimized libraries while mapping the buffers in external memory?
If so, alternate way/suggestions to use optimized libraries for FFT processing with mapping buffers in external memory(L3).
All arrays and data that are passed to the FFT functions cfftf, ifftf, and rfftf_2 must be allocated in internal memory.
There are no versions of these functions that support data in external memory.
The cfftf, ifftf, and rfftf_2 library functions are optimized implementation of an FFT functions. It has been designed to make the best use of the SHARC architecture and therefore uses processor's SIMD mode to increase its throughput.
Normally the DSP run-time library provides alternative functions that can be used with external memory if the switch -no-simd has been specified.
Unfortunately, there is no such equivalent implementation for the cfftf, ifftf, and rfftf_2 functions (because their design is predicated on processing data from internal memory at maximum efficiency).
To calculate an FFT using data in external memory, we have to use one of the function cfft, ifft, or rfft and the switch -no-simd.