问题
Can I use the Accelerate Framework to sum an array of unsigned 8-bit integers without converting to an array of floats.
My current approach is:
vDSP_vfltu8(intArray, 1, floatArray, 1, size);
vDSP_sve(floatArray, 1, &result, size);
But vDSP_vfltu8 is quite slow.
回答1:
- If it is important to you that
vDSP_vfltu8( )be fast, please file a bug report. If there's any question, file a bug report. Inadequate performance is a bug, and will be treated as such if you report it. Library writers use this sort of feedback to determine how to prioritize their work; your bug report is the difference between a function being at the front of the queue for optimization and it being #1937 in the queue. - As has been hinted, integer accumulation is complicated by overflow concerns, but if it would be useful to have an optimized function for a specific case provided by the vDSP library, please file a bug report to request such a function (noticing a pattern?). Library writers are not psychic, and do not write functions that are not requested. Be sure to explain how you would use such a function--given this information, they may come up with a slightly different function that is even more useful to you.
- If you decide to write some NEON code yourself, you will want to make use of the
vaddw_u8( )intrinsic.
来源：https://stackoverflow.com/questions/5567517/sum-array-of-unsigned-8-bit-integers-using-the-accelerate-framework