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#ifdef ZX81_RNG
/*
* This is my favorite tiny RNG, If you had a ZX81 you may recognise it :-)
* (RdeBath)
*/
#include <stdlib.h>
#define MAXINT (((unsigned)-1)>>1)
static unsigned int sseed = 0;
int rand()
{
return (sseed = (((sseed + 1L) * 75L) % 65537L) - 1) & MAXINT;
}
void srand(seed)
unsigned int seed;
{
sseed = seed;
}
#else
/*
* This generator is a combination of three linear congruential generators
* with periods or 2^15-405, 2^15-1041 and 2^15-1111. It has a period that
* is the product of these three numbers.
*/
static int seed1 = 1;
static int seed2 = 1;
static int seed3 = 1;
#define MAXINT (((unsigned)-1)>>1)
#define CRANK(a,b,c,m,s) \
q = s/a; \
s = b*(s-a*q) - c*q; \
if(s<0) s+=m;
int rand()
{
register int q;
CRANK(206, 157, 31, 32363, seed1);
CRANK(217, 146, 45, 31727, seed2);
CRANK(222, 142, 133, 31657, seed3);
return seed1 ^ seed2 ^ seed3;
}
void srand(seed)
unsigned int seed;
{
seed &= MAXINT;
seed1 = seed % 32362 + 1;
seed2 = seed % 31726 + 1;
seed3 = seed % 31656 + 1;
}
#endif
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