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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, z;

   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