Portable, self-contained replacements for RANDOM_STUFF()

[botmeister]

You can use a seed derived from the system clock, that way each time your comupter app runs, it will use a different seed.

[Whistler]

this is related with this thread, so instead opening a new one, just posting here.

well here is my implemention of random generator derived from an article in "Game Programming Gems", with a bit improvement, which is less "twisted" but random enough I guess:

PHP Code:

static long glSeed = 0, glGen2 = 0, glGen1 = 0; // our random number generator's seed

/**
 * This function initializes the random seed based on the initial seed value pass in the
 * initial_seed parameter.
 */
void lsrand(unsigned long initial_seed)
{
   // Pick two large integers such that one is double the other
   glGen2 = 3719;
   glGen1 = glGen2 / 2;

   // fill in the initial seed of the random number generator
   glSeed = (glGen1 * initial_seed) + glGen2;
}

/**
 * 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 f$
 * able to generate 32-bit random numbers. Isn't that nice?
 */
long lrand(void)
{
   if (glSeed == 0) // if the random seed isn't initialized...
      lsrand(time(NULL)); // initialize it first
   glSeed = (glGen1 * glSeed) + glGen2; // do some twisted math
   return glSeed > 0 ? glSeed : -glSeed; // and return absolute value of the result
}

/**
 * This function returns a random integer number between (and including) the starting and
 * ending values passed by parameters from and to.
 */
long RandomLong(long from, long to)
{
   if (to <= from)
      return from;

   return from + lrand() / (LONG_MAX / (to - from + 1));
}

/**
 * This function returns a random floating-point number between (and including) the starting
 * and ending values passed by parameters from and to.
 */
long RandomLong(long from, long to)
{
   if (to <= from)
      return from;

   return from + (float)lrand() / (LONG_MAX / (to - from));
} 


btw, as long as the PDF spec. and free pdf viewers like xpdf are publically available (gv is also able to open pdf file), there is not problem to use the pdf format and it still sucks less than e.g., .doc format (except its DRM "features")...