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 reciprocal_value(u32 d)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 } 27 EXPORT_SYMBOL(reciprocal_value); 28