Messages in this thread | | | Date | Thu, 16 Jan 2014 10:22:04 +0100 | From | Daniel Borkmann <> | Subject | Re: [PATCH net-next 1/2] random32: add prandom_u32_lt_N and convert "misuses" of reciprocal_divide |
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On 01/16/2014 01:29 AM, Joe Perches wrote: > On Thu, 2014-01-16 at 00:23 +0100, Daniel Borkmann wrote: >> Many functions have open coded a function that return a random >> number in range [0,N-1]. Also, only because we have a function >> that is named reciprocal_divide(), it has not much to do with >> the pupose where it is being used when a previous reciprocal_value() >> has not been obtained. > > prandom_u32_lt_N? > > I do not like the camelcase name and thought the > prandom_u32_max was better.
Hm, you wanted to have the name intuitive, right ... so u32 prandom_u32_lt_N(u32 N) suggests "less then N". If you are saying "_max" here, then you should keep in mind that the maximum result you get from here is "max-1", not "max". But whatever, it's just a name.
> How about using > > u32 prandom_u32_max(u32 max) > { > return (u32)(((u64)prandom_u32() * max) >> 32); > } > > u32 prandom_u32_range(u32 a, u32 b) > { > if (b < a) > swap(a, b); > > return a + (u32)(((u64)prandom_u32() * (b - a)) >> 32); > }
I didn't introduce the last one as it wasn't used in the patch.
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