Image by Virens, licensed under the Creative Commons Attribution 3.0 Unported license.
This is an implementation of the Cooley-Tukey FFT algorithm for one of Tensilica's Xtensa processor platforms. The Tensilica Instruction Extension hardware-description DSL is utilized to customize the core Xtensa core architecture by means of additional specialized registers and instructions which make it possible to perform the specialized task of computing a DIT/DIF FFT at significantly higher speeds than would ordinarily be possible with the base ISA alone. Hardware acceleration results in a > x25 speedup for moderately large inputs:
See the report under submodules/report/pdf for a detailed
description of the design and implementation of this project as well as
performance and chip area analyses.
The algorithm itself is implemented in assembly in project/source/asm/fft.S,
the instruction set extensions are implemented in project/source/tie/fft.tie
in the aforementioned TIE language. In order to actually simulate this design
you would need a commercial licence for the Xtensa SDK.