/* random.c - Random number generators - Don Yang (uguu.org)

   01/02/05
                                                                           */

#include<stdio.h>
#include<stdlib.h>


/* Random seed from OCaml's random.ml */
static unsigned int LFR_RandomSeed[55] =
{
   509760043,  399328820, 99941072,   112282318, 611886020, 516451399,
   626288598,  337482183, 748548471,  808894867, 657927153, 386437385,
   42355480,   977713532, 311548488,  13857891,  307938721, 93724463,
   1041159001, 444711218, 1040610926, 233671814, 664494626, 1071756703,
   188709089,  420289414, 969883075,  513442196, 275039308, 918830973,
   598627151,  134083417, 823987070,  619204222, 81893604,  871834315,
   398384680,  475117924, 520153386,  324637501, 38588599,  435158812,
   168033706,  585877294, 328347186,  293179100, 671391820, 846150845,
   283985689,  502873302, 718642511,  938465128, 962756406, 107944131,
   192910970
};
static unsigned int LFR_RandomIdx = 0;

/* Random number generator using linear feedback registers */
static int LFR_RandomInt(void)
{
   LFR_RandomIdx = (LFR_RandomIdx + 1) % 55;
   return
      (int)(LFR_RandomSeed[LFR_RandomIdx] +=
            LFR_RandomSeed[(LFR_RandomIdx + 24) % 55]) &
      0x3fffffff;
}


/* Random seed */
static unsigned int PR_RandomSeed = 12345;

/* Random number generator using power residue function */
static int PR_RandomInt(void)
{
   PR_RandomSeed = PR_RandomSeed * 22695477 + 1;
   return (int)(PR_RandomSeed & 0x3fffffff);
}


/* Test driver */
int main(int argc, char **argv)
{
   FILE *outfile;
   int i, size;

   if( argc < 4 )
      return printf("%s <outfile> <size> <seed>\n", *argv);
   if( (outfile = fopen(argv[1], "wb+")) == NULL )
      return printf("Can not create %s\n", argv[1]);

   PR_RandomSeed = (unsigned int)atoi(argv[3]);
   for(i = 0; i < 55; i++)
      LFR_RandomSeed[i] ^= PR_RandomInt();

   size = atoi(argv[2]);
   for(i = 0; i < size; i++)
      (void)fputc(LFR_RandomInt() & 255, outfile);
   return fclose(outfile);
}