Fastrange: A fast alternative to the modulo reduction

Fastrange: A fast alternative to the modulo reduction(github.com)

21 points by henrikm85 9 years ago | 4 comments

dmitrygr 9 years ago |

This is how we've been doing division by a constant in the embedded world since...forever

this is so well known in fact that arm gcc defaults to this when a proper constant exists if you do division or modulus operator...

lvs 9 years ago | |

I was going to say, this is an ancient and well-known optimization. I have no idea how old it is, but I would venture it's been a regular practice for at least two decades.

rkwasny 9 years ago |

Shouldn't a good compiler apply this type of optimisations?

AstralStorm 9 years ago | |

It generally does. (GCC, Clang and ICC) But it cannot simplify the operation on some architectures or when the factor is variable.

The "fastrange" is a very different operation on prime factors than modulo.