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mod division improvments

General and Gameplay Programming Programming

Started by vaneger March 26, 2004 08:15 PM

3 comments, last by vaneger 20 years ago

vaneger

100

Author

March 26, 2004 08:15 PM


#define MOD(x,y) y & (x-1)

i found this some where but it is inaccurate does any one know how ot make a more accurate and faster MOD function?

Sneftel

1,788

March 26, 2004 08:21 PM

That function is accurate for powers of two only. Other than powers of two, there''s no general way to do modulus with a constant that''s faster than just using modulus.

"Sneftel is correct, if rather vulgar." --Flarelocke

vaneger

100

Author

March 26, 2004 08:30 PM

not even using asm ?

Beer Hunter

712

March 26, 2004 08:34 PM

If there were, the compiler would already use it. Worry about how your code reads; let the compiler make it fast.

Sneftel

1,788

March 27, 2004 12:31 AM

quote:Original post by vaneger
not even using asm ?

ASM isn''t a magic bullet. It''s just a lower-level language. More or less the same machine language instructions will be generated by the compiler as would be written by you, anyway. The number of situations where the best way to optimize is to rewrite stuff in ASM is very, very small.

"Sneftel is correct, if rather vulgar." --Flarelocke