random.c

来自「一个微型操作系统源码」· C语言 代码 · 共 19 行

#include <stdlib.h>

static unsigned long long next = 0;

int
rand(void)
{
  next = next * 1103515245L + 12345;
  next = (next<<15) ^ (next >> 27);
  return (int)((next >> 4) & RAND_MAX);
}

void
srand(unsigned long seed)
{
  next = seed;
}