Overview of the freedom compiler for mapping DSP software to FPGAs

Applications that require digital signal processing (DSP) functions are typically mapped onto general purpose DSP processors. With the introduction of advanced FPGA architectures with built-in DSP support, a new hardware alternative is available for DSP designers. By exploiting its inherent parallelism, it is expected that FPGAs can outperform DSP processors. However, the migration of assembly code to hardware is typically a very arduous process. This paper describes the process and considerations for automatically translating software assembly and binary codes targeted for general DSP processors into Register Transfer Level (RTL) VHDL or Verilog code to be mapped onto commercial FPGAs. The Texas Instruments C6000 DSP processor architecture has been used as the DSP processor platform, and the Xilinx Virtex II as the target FPGA. Various optimizations are discussed, including loop unrolling, induction variable analysis, memory and register optimizations, scheduling and resource binding. Experimental results on resource usage and performance are shown for ten software binary benchmarks in the signal processing and image processing domains. Results show performance gains of 3-20x in terms of reductions in execution cycles and 1.3-5x in terms of reductions in execution times for the FPGA designs over that of the DSP processors in terms of reductions of execution cycles.