6.16. Choosing a Diamond

All of the Diamond Standard Series processor cores are based on a general-purpose, 32-bit RISC ISA, so all of the cores can be assigned general-purpose tasks on an SOC. However, each of the Diamond processor cores has been shaped for specific applications:

• The 108Mini core is a good, general-purpose processor that’s been trimmed to minimum size. It’s intended for use as a control processor with code running almost exclusively out of the processor core’s local instruction memory. This instruction memory can be loaded by the 108Mini itself using load instructions directed to main memory over the processor core’s PIF bus or by an external agent using the 108Mini’s inbound-PIF feature. The 108Mini core sacrifices the performance-enhancing zero-overhead-loop hardware for reduced core size.

• The 212GP core is a fast, general-purpose processor with instruction and data caches to achieve good overall performance when executing larger programs.

• The 232L processor core is similar to the 212GP core but adds a full-featured MMU for running operating systems that require a full demand-paged MMU with memory protection, such as Linux.

• The 570T processor core is a high-performance CPU with 3-way static superscalar operation. Although only about twice as large as its scalar processor counterparts, the 570T delivers more software execution speed per clock cycle than any processor core in its class. The core also includes two queue interfaces for good performance in flow-through applications.

• The 330HiFi processor core contains a specialized, 24-bit DSP for audio applications. It includes approximately 300 audio-specific instructions for handling and manipulating special audio data types and two queue interfaces for good performance in flow-through applications. A full set of firmware audio codecs (written entirely in C) is available for use with the 330HiFi core.

• The 545CK DSP is a 3-issue static superscalar processor with a SIMD unit containing eight 16-bit MACs. The 545CK DSP core offers the highest performance of any available DSP core, as measured by BDTI benchmarks. It’s targeted at DSP applications that require very fast execution speeds such as signal and image processing while retaining a general-purpose processor core that excels at efficiently executing control code.

All of the Xtensa and Diamond processor cores are accompanied by tailored versions of the XCC C/C++ compiler, which exploits the unique abilities of each processor whenever possible. The close pairing of processor and compiler means that firmware developers can code in C or C++ and only rarely will they need to drop down to assembly-language programming to improve code performance.