[computer-go] Fast random int generation

[Łukasz Lew]

Someone (Don?) asked for a fast random generator.
Here it is.

Standard library rand() in linux takes about 200 clock cycles.
pm::rand() takes 30cc on my hardware.

namespace pm {
  static unsigned long seed = 12345;

  unsigned long rand () {
    unsigned long hi, lo;
    lo = 16807 * (seed & 0xffff);
    hi = 16807 * (seed >> 16);
    lo += (hi & 0x7fff) << 16;
    lo += hi >> 15;
    if (lo > 0x7fffffff) lo -= 0x7fffffff;
    seed = (long) lo;
    return lo;
  }

}

Regards,
Łukasz