Usermode/Libraries/libc.so_src/rand.c

   1 /*
   2  * Acess2 Lib C
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * rand.c
   6  * - srand/rand/rand_p functions
   7  */
   8 #include <stdlib.h>
   9
  10 // === GLOBALS ===
  11 unsigned int    _rand_state_x = 123456789;
  12 unsigned int    _rand_state_y = 362436069;
  13 unsigned int    _rand_state_z = 521288629;
  14 unsigned int    _rand_state_w = 88675123;
  15
  16 // === FUNCTIONS ===
  17 int rand_p(unsigned int *seedp)
  18 {
  19         const int const_a = 0x731ADE, const_c = 12345;
  20         // Linear Congruency
  21         *seedp = *seedp * const_a + const_c;
  22         return *seedp;
  23 }
  24
  25 void srand(unsigned int seed)
  26 {
  27         _rand_state_x = rand_p( &seed );
  28         _rand_state_y = rand_p( &seed );
  29         _rand_state_z = rand_p( &seed );
  30         _rand_state_w = rand_p( &seed );
  31 }
  32
  33 int rand(void)
  34 {
  35         unsigned int t;
  36
  37         t = _rand_state_x ^ (_rand_state_x << 11);
  38         _rand_state_x = _rand_state_y; _rand_state_y = _rand_state_z; _rand_state_z = _rand_state_w;
  39         return _rand_state_w = _rand_state_w ^ (_rand_state_w >> 19) ^ t ^ (t >> 8);
  40 }
  41