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April 29, 2016 xoroshiro128+ random number generator | ||||
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Spotted this reddit post the other day: https://www.reddit.com/r/programming/comments/4gtlfz/xoroshiro128_the_fastest_fullperiod_pseudorandom/ ... and it reminded me that I've been meaning for some time to follow up on the interesting RNG designs by Sebastiano Vigna and colleagues. Since I had a free moment, I thought I'd knock up a D port of the public-domain C reference code available here: http://xorshift.di.unimi.it/xoroshiro128plus.c It's a first draft and obviously needs documentation, tests, etc. before I submit it to Phobos, but I thought I'd throw it out here if anyone wants to play with it and/or comment. I'll also try to follow up in the next days with an xorshift1024* implementation, which should be similarly straightforward. Code follows -- enjoy! :-) struct Xoroshiro128plus { public: enum bool isUniformRandom = true; /// Range primitives enum bool empty = false; /// ditto ulong front() @property @safe const nothrow pure { return s[0] + s[1]; } /// ditto void popFront() @safe nothrow pure { immutable ulong s1 = s[1] ^ s[0]; s[0] = rotateLeft(s[0], 55) ^ s1 ^ (s1 << 14); s[1] = rotateLeft(s1, 36); } void seed(ulong s0, ulong s1) @safe nothrow pure in { // seeds are not both 0 assert(!(!s0 && !s1)); } body { s[0] = s0; s[1] = s1; } void seed(ulong[2] s01) @safe nothrow pure in { // seeds are not both 0 assert(!(!s01[0] && !s01[1])); } body { s[] = s01[]; } private: ulong[2] s; static ulong rotateLeft(ulong x, int k) @safe nothrow pure in { assert(k <= 64); } body { return (x << k) | (x >> (64 - k)); } } |
April 30, 2016 Re: xoroshiro128+ random number generator | ||||
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Posted in reply to Joseph Rushton Wakeling | On Friday, 29 April 2016 at 21:40:49 UTC, Joseph Rushton Wakeling wrote:
> Spotted this reddit post the other day:
> https://www.reddit.com/r/programming/comments/4gtlfz/xoroshiro128_the_fastest_fullperiod_pseudorandom/
@nogc :)
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April 30, 2016 Re: xoroshiro128+ random number generator | ||||
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Posted in reply to Nordlöw | On Saturday, 30 April 2016 at 08:54:39 UTC, Nordlöw wrote:
> On Friday, 29 April 2016 at 21:40:49 UTC, Joseph Rushton Wakeling wrote:
>> Spotted this reddit post the other day:
>> https://www.reddit.com/r/programming/comments/4gtlfz/xoroshiro128_the_fastest_fullperiod_pseudorandom/
>
> @nogc :)
Hah, nicely spotted :-)
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April 30, 2016 Re: xoroshiro128+ random number generator | ||||
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Posted in reply to Joseph Rushton Wakeling | On Saturday, 30 April 2016 at 11:04:14 UTC, Joseph Rushton Wakeling wrote:
> On Saturday, 30 April 2016 at 08:54:39 UTC, Nordlöw wrote:
>> On Friday, 29 April 2016 at 21:40:49 UTC, Joseph Rushton Wakeling wrote:
>>> Spotted this reddit post the other day:
>>> https://www.reddit.com/r/programming/comments/4gtlfz/xoroshiro128_the_fastest_fullperiod_pseudorandom/
>>
>> @nogc :)
>
> Hah, nicely spotted :-)
More importantly, the public fields of this generator should include:
enum ulong min = ulong.min;
enum ulong max = ulong.max;
... otherwise it won't work with `uniform` or anything that depends on it.
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