Difference between revisions of "Seedable PRNG"
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Gigs Taggart (talk | contribs) (update on periodicity) |
Huney Jewell (talk | contribs) m (Avoid line overflow) |
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{{LSL Header}} | |||
== md5 based seedable PRNG == | |||
It's not the fastest thing but it doesn't seem to have much if any output skew, and I couldn't detect any periodicity in the first 100,000 cycles. | It's not the fastest thing but it doesn't seem to have much if any output skew, and I couldn't detect any periodicity in the first 100,000 cycles. | ||
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integer prng_get() | integer prng_get() | ||
{ | { | ||
gLastHash=llMD5String(gLastHash, gSeed); | gLastHash=llMD5String(gLastHash, gSeed); | ||
//the bitwise thingy gets rid of negative numbers | |||
return (integer)("0x" + llGetSubString(gLastHash, 0, 7)) & 0x7FFFFFFF; } | |||
</pre> | </pre> | ||
[[Category: LSL Examples]] | [[Category: LSL Examples]] | ||
Revision as of 05:52, 7 September 2007
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md5 based seedable PRNG
It's not the fastest thing but it doesn't seem to have much if any output skew, and I couldn't detect any periodicity in the first 100,000 cycles.
//new md5 based seedable PRNG
//By: Gigs Taggart
//Released under BSD License.
//http://www.opensource.org/licenses/bsd-license.php
integer gSeed=0;
string gLastHash;
prng_seed(integer seed)
{
gSeed=seed;
}
integer prng_get()
{
gLastHash=llMD5String(gLastHash, gSeed);
//the bitwise thingy gets rid of negative numbers
return (integer)("0x" + llGetSubString(gLastHash, 0, 7)) & 0x7FFFFFFF; }