On 09-09-2013, at 9:10 AM, "J. Vuletich (mail lists)" <juanlists at jvuletich.org> wrote:
> 
> 
> The idea is to approximate 256/255 by 257/256. So, instead of doing x/255 (slow) or x>>8 (incorrect), you do x*257 >> 16, or better yet (x<<8 + x) >> 16. Two shift and an add instead of a division. The error is less than 1/65535, and negligible for 8 bit output.
> 
> I hope this is still relevant.

Ooh, nice. Two instruction cycles for an ARM and probably the second shift could be merged into whatever the following operation is.


tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
"Bollocks," said Pooh being more forthright than usual