Efficient implementation of composite length fast FIR filtering on the “ADSP-2100”

The paper proposes an efficient implementation of fast composite length FIR algorithms on the digital signal processor (DSP) “ADSP-2100”, which closely follows the mathematical structure of the algorithm. The difficulty is to keep as much as possible the improvement brought by the reduction of the complexity without exceeding the DSP resources (number of registers, pointers, memory,...). This difficulty was already pointed out in previous papers, in which the algorithm was restricted to a single decomposition due to these constraints. Particular attention was devoted to this problem. The solution is to structure the algorithm in such a way that the organization of data in the memory is optimised. The authors propose an implementation requiring only five pointers whatever the number of iterations. An improvement of more than 50% in terms of actual throughput (number of cycles per point) compared to the implementation of the direct convolution is achieved