random.h

   1 #ifndef ZZGO_RANDOM_H
   2 #define ZZGO_RANDOM_H
   3
   4 #include <stdint.h>
   5
   6 void fast_srandom(unsigned long seed);
   7 unsigned long fast_getseed(void);
   8
   9 /* Note that only 16bit numbers can be returned. */
  10 uint16_t fast_random(unsigned int max);
  11 /* Use this one if you want larger numbers. */
  12 static uint32_t fast_irandom(unsigned int max);
  13
  14 /* Get random number in [0..1] range. */
  15 float fast_frandom();
  16
  17
  18 static inline uint32_t
  19 fast_irandom(unsigned int max)
  20 {
  21         if (max <= 65536)
  22                 return fast_random(max);
  23         int himax = (max - 1) / 65536;
  24         uint16_t hi = fast_random(himax + 1);
  25         return ((uint32_t)hi << 16) | fast_random(hi < himax ? 65536 : max % 65536);
  26 }
  27
  28 #endif