Q:

Where can I find Digital Signal Processing (DSP) libraries for FFT (Fast Fourier Transform) operations etc.?

A:

As a part of the CMSIS standard, ARM provides a DSP function library, including FFT. These functions are also distributed by Energy Micro in our CMSIS package (available as a separate download here or in Simplicity Studio). You can find the files under CMSIS/DSP_Lib in the Simplicity Studio work folder.