CalmADM™: an audio DSP module based on CalmRISC™

We introduce CalmADM, an audio DSP module based on CalmRISC. CalmADM is based on Samsung´s 16-bit microprocessor, CalmRISC16, and its 24-bit DSP coprocessor, CalmMAC24. Two new architectures are adopted in CalmADM. One is shared data cache. With this new caching scheme, we can reduce on-chip memory area while not losing cache performance and programming flexibility. The other is sequential stream buffer. This small buffer takes full charge of input/output audio stream data. Therefore, data caches in CalmADM do not suffer from performance loss caused by cache misses for input/output stream data. The area of CalmADM is about 290K in gate count including on-chip cache memories. The performance we achieved is 38 MIPS for 5.1-channel Dolby AC3 decoding and 40 MIPS for 7.1-channel MPEG2 audio layer2 decoding, including off-chip memory access overhead.