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Merge pull request #2312 from gmaxwell/random_random

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ApproximateBestSubset internal RNG to prevent degenerate behavior.
This commit is contained in:
Gavin Andresen
2013-02-22 08:57:38 -08:00
parent 1167af7e5c 907a2aa4c7
commit aaeb443791
4 changed files with 111 additions and 13 deletions
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26
src/util.h
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@@ -404,13 +404,27 @@ bool SoftSetArg(const std::string& strArg, const std::string& strValue);
*/
bool SoftSetBoolArg(const std::string& strArg, bool fValue);
/**
* MWC RNG of George Marsaglia
* This is intended to be fast. It has a period of 2^59.3, though the
* least significant 16 bits only have a period of about 2^30.1.
*
* @return random value
*/
extern uint32_t insecure_rand_Rz;
extern uint32_t insecure_rand_Rw;
static inline uint32_t insecure_rand(void)
{
insecure_rand_Rz=36969*(insecure_rand_Rz&65535)+(insecure_rand_Rz>>16);
insecure_rand_Rw=18000*(insecure_rand_Rw&65535)+(insecure_rand_Rw>>16);
return (insecure_rand_Rw<<16)+insecure_rand_Rz;
}
/**
* Seed insecure_rand using the random pool.
* @param Deterministic Use a determinstic seed
*/
void seed_insecure_rand(bool fDeterministic=false);
/** Median filter over a stream of values.
* Returns the median of the last N numbers