Difference between revisions of "Seedable PRNG"
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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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//new md5 based seedable PRNG | //new md5 based seedable PRNG | ||
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} | } | ||
} | } | ||
</ | </lsl> | ||
[[Category: LSL Examples]] | [[Category: LSL Examples]] [[Category: LSL Encryption]] | ||
Revision as of 12:21, 1 January 2008
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See also: llFrand, llListRandomize, Pseudo-random_Number_Generator
Note: The 32bit_Hash example presents just the conversion to integer from llMD5String.
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.
<lsl>
//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;
}
default {
state_entry()
{
prng_seed(2007031901);
string line;
integer index;
line = "";
for (index = 0; index < 9; ++index)
{
line += " " + (string) prng_get();
}
llOwnerSay(line);
line = "";
for (index = 0; index < 30; ++index)
{
line += " " + (string) (1 + (prng_get() % 6));
}
llOwnerSay(line);
llOwnerSay("OK");
}
} </lsl>