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added a thread-safe and cross-plateform random number generator

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git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@3373 b45a01b8-16f6-495d-af2f-9b41ad6348cc
This commit is contained in:
csoler 2010-08-15 20:20:51 +00:00
parent f0da158dbe
commit 30e4509043
5 changed files with 302 additions and 3 deletions
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73
libretroshare/src/util/rsrandom.cc Normal file
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#include <stdlib.h>
#include "rsrandom.h"
uint32_t RSRandom::index = 0 ;
static bool auto_seed = RSRandom::seed(time(NULL)) ;
std::vector<uint32_t> RSRandom::MT(RSRandom::N,0u) ;
RsMutex RSRandom::rndMtx ;
bool RSRandom::seed(uint32_t s)
{
RsStackMutex mtx(rndMtx) ;
MT.resize(N,0) ; // because MT might not be already resized
uint32_t j ;
MT[0]= s & 0xffffffffUL;
for (j=1; j<N; j++)
MT[j] = (1812433253UL * (MT[j-1] ^ (MT[j-1] >> 30)) + j) & 0xffffffffUL ;
return true ;
}
void RSRandom::locked_next_state()
{
for(uint32_t i=0;i<N;++i)
{
uint32_t y = ((MT[i]) & UMASK) | ((MT[(i+1)%(int)N]) & LMASK) ;
MT[i] = MT[(i + M) % (int)N] ^ (y >> 1) ;
if((y & 1) == 1)
MT[i] = MT[i] ^ 0x9908b0df ;
}
index = 0 ;
}
uint32_t RSRandom::random_u32()
{
uint32_t y;
{
RsStackMutex mtx(rndMtx) ;
y = MT[index++] ;
if(index == N)
locked_next_state();
}
// Tempering
y ^= (y >> 11);
y ^= (y << 7 ) & 0x9d2c5680UL;
y ^= (y << 15) & 0xefc60000UL;
y ^= (y >> 18);
return y;
}
uint64_t RSRandom::random_u64()
{
return ((uint64_t)random_u32() << 32ul) + random_u32() ;
}
float RSRandom::random_f32()
{
return random_u32() / (float)(~(uint32_t)0) ;
}
double RSRandom::random_f64()
{
return random_u64() / (double)(~(uint64_t)0) ;
}