What are the best practices and standards for ARM floating point unit code documentation?

2 FPU Registers and Instructions

The next thing you should document is the FPU registers and instructions that your code uses. ARM FPU registers are either single-precision (S0-S31) or double-precision (D0-D31), and some of them can be accessed as vectors (Q0-Q15). You should document how your code allocates and uses these registers, and how it preserves or restores their values across function calls or interrupts. You should also document the FPU instructions that your code uses, such as arithmetic, comparison, conversion, and load/store operations, and explain their purpose and logic.

3 FPU Data Types and Formats

The third thing you should document is the FPU data types and formats that your code uses. ARM FPU supports several data types, such as single-precision, double-precision, half-precision, and fixed-point, each with different ranges and precisions. You should document the data types that your code uses and how they are declared, initialized, and manipulated. You should also document the data formats that your code uses, such as IEEE 754, alternative formats, or custom formats, and how they are encoded, decoded, and converted.

4 FPU Performance and Optimization

The fourth thing you should document is the FPU performance and optimization that your code achieves. FPU code can have a significant impact on the speed, power consumption, and memory usage of your software, so you should document how you measure and improve these aspects. You should document the FPU performance metrics that you use, such as cycles, latency, throughput, and energy efficiency, and how you collect and analyze them. You should also document the FPU optimization techniques that you use, such as instruction scheduling, pipelining, parallelism, and vectorization, and how they affect the FPU performance.

5 FPU Testing and Debugging

The fifth thing you should document is the FPU testing and debugging that your code undergoes. FPU code can be prone to errors, such as overflow, underflow, rounding, NaN, and infinity, so you should document how you detect and correct them. You should document the FPU testing methods that you use, such as unit testing, integration testing, regression testing, and stress testing, and how they cover the FPU functionality and edge cases. You should also document the FPU debugging tools that you use, such as emulators, simulators, debuggers, and profilers, and how they help you identify and fix the FPU issues.

6 FPU Compatibility and Portability

The sixth thing you should document is the FPU compatibility and portability that your code ensures. FPU code can be affected by the hardware and software environment that it runs on, such as the CPU architecture, the operating system, the compiler, and the library, so you should document how you adapt and support different scenarios. You should document the FPU compatibility issues that your code faces, such as endianness, alignment, interworking, and exception handling, and how you resolve or avoid them. You should also document the FPU portability features that your code provides, such as abstraction layers, macros, configuration files, and conditional compilation, and how they enable or facilitate cross-platform development.