Function lrand

source/src/bot/bot_util.cpp:28–63

long lseed; // our random number generator's seed

long lrand (void)
{
     // this function is the equivalent of the rand() standard C library function,
     // except that whereas rand() works only with short integers
     // (i.e. not above 32767), this function is able to generate 32-bit random
     // numbers. Isn't that nice ?
     // credits go to Ray Gardner for his fast implementation of minimal random
     // number generators
     // http://c.snippets.org/snip_lister.php?fname=rg_rand.c

     // compose the two 16-bit parts of the long integer and assemble them
     static unsigned long lrand_lo, lrand_hi;
     lrand_lo = 16807 * (long) (lseed & 0xFFFF); // low part
     lrand_hi = 16807 * (long) ((unsigned long) lseed >> 16);
     // high part
     lrand_lo += (lrand_hi & 0x7FFF) << 16;
     // assemble both in lrand_lo
     // is the resulting number greater than LRAND_MAX (half the capacity) ?
     if (lrand_lo > LRAND_MAX)
     {
          lrand_lo &= LRAND_MAX; // then get rid of the disturbing bit
          lrand_lo++; // and increase it a bit (to avoid overflow problems, I suppose)
     }

     lrand_lo += lrand_hi >> 15;
     // now do twisted maths to generate the next seed
     // is the resulting number greater than LRAND_MAX (half the capacity) ?
     if (lrand_lo > LRAND_MAX)
     {
          lrand_lo &= LRAND_MAX; // then get rid of the disturbing bit
          lrand_lo++; // and increase it a bit (to avoid overflow problems, I suppose)
     }
     // now we've got our (pseudo-)random number.
     lseed = (long) lrand_lo; // put it in the seed for next time
     return (lseed); // and return it. Yeah, simple as that.
}

void lsrand (unsigned long initial_seed)
{