You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
131 lines
2.4 KiB
131 lines
2.4 KiB
//========= Copyright Valve Corporation, All rights reserved. ============//
|
|
//
|
|
// Purpose: Basic random number generator
|
|
//
|
|
// $NoKeywords: $
|
|
//===========================================================================//
|
|
|
|
|
|
#include <time.h>
|
|
#include "Random.h"
|
|
|
|
// memdbgon must be the last include file in a .cpp file!!!
|
|
#include "tier0/memdbgon.h"
|
|
|
|
#define IA 16807
|
|
#define IM 2147483647
|
|
#define IQ 127773
|
|
#define IR 2836
|
|
#define NTAB 32
|
|
#define NDIV (1+(IM-1)/NTAB)
|
|
|
|
static long idum = 0;
|
|
|
|
void SeedRandomNumberGenerator(long lSeed)
|
|
{
|
|
if (lSeed)
|
|
{
|
|
idum = lSeed;
|
|
}
|
|
else
|
|
{
|
|
idum = -time(NULL);
|
|
}
|
|
if (1000 < idum)
|
|
{
|
|
idum = -idum;
|
|
}
|
|
else if (-1000 < idum)
|
|
{
|
|
idum -= 22261048;
|
|
}
|
|
}
|
|
|
|
long ran1(void)
|
|
{
|
|
int j;
|
|
long k;
|
|
static long iy=0;
|
|
static long iv[NTAB];
|
|
|
|
if (idum <= 0 || !iy)
|
|
{
|
|
if (-(idum) < 1) idum=1;
|
|
else idum = -(idum);
|
|
for (j=NTAB+7;j>=0;j--)
|
|
{
|
|
k=(idum)/IQ;
|
|
idum=IA*(idum-k*IQ)-IR*k;
|
|
if (idum < 0) idum += IM;
|
|
if (j < NTAB) iv[j] = idum;
|
|
}
|
|
iy=iv[0];
|
|
}
|
|
k=(idum)/IQ;
|
|
idum=IA*(idum-k*IQ)-IR*k;
|
|
if (idum < 0) idum += IM;
|
|
j=iy/NDIV;
|
|
iy=iv[j];
|
|
iv[j] = idum;
|
|
|
|
return iy;
|
|
}
|
|
|
|
// fran1 -- return a random floating-point number on the interval [0,1)
|
|
//
|
|
#define AM (1.0/IM)
|
|
#define EPS 1.2e-7
|
|
#define RNMX (1.0-EPS)
|
|
float fran1(void)
|
|
{
|
|
float temp = (float)AM*ran1();
|
|
if (temp > RNMX) return (float)RNMX;
|
|
else return temp;
|
|
}
|
|
|
|
#ifndef _XBOX
|
|
float RandomFloat( float flLow, float flHigh )
|
|
{
|
|
if (idum == 0)
|
|
{
|
|
SeedRandomNumberGenerator(0);
|
|
}
|
|
|
|
float fl = fran1(); // float in [0,1)
|
|
return (fl * (flHigh-flLow)) + flLow; // float in [low,high)
|
|
}
|
|
#endif
|
|
|
|
long RandomLong( long lLow, long lHigh )
|
|
{
|
|
if (idum == 0)
|
|
{
|
|
SeedRandomNumberGenerator(0);
|
|
}
|
|
|
|
unsigned long maxAcceptable;
|
|
unsigned long x = lHigh-lLow+1;
|
|
unsigned long n;
|
|
if (x <= 0 || MAX_RANDOM_RANGE < x-1)
|
|
{
|
|
return lLow;
|
|
}
|
|
|
|
// The following maps a uniform distribution on the interval [0,MAX_RANDOM_RANGE]
|
|
// to a smaller, client-specified range of [0,x-1] in a way that doesn't bias
|
|
// the uniform distribution unfavorably. Even for a worst case x, the loop is
|
|
// guaranteed to be taken no more than half the time, so for that worst case x,
|
|
// the average number of times through the loop is 2. For cases where x is
|
|
// much smaller than MAX_RANDOM_RANGE, the average number of times through the
|
|
// loop is very close to 1.
|
|
//
|
|
maxAcceptable = MAX_RANDOM_RANGE - ((MAX_RANDOM_RANGE+1) % x );
|
|
do
|
|
{
|
|
n = ran1();
|
|
} while (n > maxAcceptable);
|
|
|
|
return lLow + (n % x);
|
|
}
|
|
|
|
|