LXR linux/lib/reciprocal

   1#include <linux/kernel.h>
   2#include <asm/div64.h>
   3#include <linux/reciprocal_div.h>
   4#include <linux/export.h>
   5
   6/*
   7 * For a description of the algorithm please have a look at
   8 * include/linux/reciprocal_div.h
   9 */
  10
  11struct reciprocal_value reciprocal_value(u32 d)
  12{
  13        struct reciprocal_value R;
  14        u64 m;
  15        int l;
  16
  17        l = fls(d - 1);
  18        m = ((1ULL << 32) * ((1ULL << l) - d));
  19        do_div(m, d);
  20        ++m;
  21        R.m = (u32)m;
  22        R.sh1 = min(l, 1);
  23        R.sh2 = max(l - 1, 0);
  24
  25        return R;
  26}
  27EXPORT_SYMBOL(reciprocal_value);
  28