使用 Thomas Wangs 整数哈希函数

获取种子并评估的辅助功能：

uint wang_hash(uint seed)
{
        seed = (seed ^ 61) ^ (seed >> 16);
        seed *= 9;
        seed = seed ^ (seed >> 4);
        seed *= 0x27d4eb2d;
        seed = seed ^ (seed >> 15);
        return seed;
 }

另一个辅助函数，用它来初始化 id 所示的缓冲区位置：

 void wang_rnd_0(__global unsigned int * rnd_buffer,int id)                
 {
     uint maxint=0;
     maxint--;
     uint rndint=wang_hash(id);
     rnd_buffer[id]=rndint;
 }

另一个在 0 和 1 之间做额外的浮点输出

 float wang_rnd(__global unsigned int * rnd_buffer,int id)                
 {
     uint maxint=0;
     maxint--; // not ok but works
     uint rndint=wang_hash(rnd_buffer[id]);
     rnd_buffer[id]=rndint;
     return ((float)rndint)/(float)maxint;
 }

初始化内核：

 __kernel void rnd_init(__global unsigned int * rnd_buffer)
 {
       int id=get_global_id(0);
       wang_rnd_0(rnd_buffer,id);  // each (id) thread has its own random seed now           
 }

单迭代内核：

 __kernel void rnd_1(__global unsigned int * rnd_buffer)
 {
      int id=get_global_id(0);

      // can use this to populate a buffer with random numbers 
      // concurrently on all cores of a gpu
      float thread_private_random_number=wang_rnd(rnd_buffer,id);
 }