Have you tried using floating point log() in FlexC, compiling and looking at the disassembly? IIRC, FlexC uses the CORDIC unit for floating point math, at least QMUL, QDIV and SQRT. I haven't tested exp() and log(), so far.
No need to look at the disassembly, the source code for __builtin_log2f and __builtin_exp2f are in the FlexProp include/libsys/powers.c file. They're not highly optimized, but I think they work OK.
Comments
Have you tried using floating point log() in FlexC, compiling and looking at the disassembly? IIRC, FlexC uses the CORDIC unit for floating point math, at least QMUL, QDIV and SQRT. I haven't tested exp() and log(), so far.
No need to look at the disassembly, the source code for __builtin_log2f and __builtin_exp2f are in the FlexProp include/libsys/powers.c file. They're not highly optimized, but I think they work OK.