LXR linux/include/linux/math64.h

   1#ifndef _LINUX_MATH64_H
   2#define _LINUX_MATH64_H
   3
   4#include <linux/types.h>
   5#include <asm/div64.h>
   6
   7#if BITS_PER_LONG == 64
   8
   9/**
  10 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
  11 *
  12 * This is commonly provided by 32bit archs to provide an optimized 64bit
  13 * divide.
  14 */
  15static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  16{
  17        *remainder = dividend % divisor;
  18        return dividend / divisor;
  19}
  20
  21/**
  22 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
  23 */
  24static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
  25{
  26        *remainder = dividend % divisor;
  27        return dividend / divisor;
  28}
  29
  30/**
  31 * div64_u64 - unsigned 64bit divide with 64bit divisor
  32 */
  33static inline u64 div64_u64(u64 dividend, u64 divisor)
  34{
  35        return dividend / divisor;
  36}
  37
  38#elif BITS_PER_LONG == 32
  39
  40#ifndef div_u64_rem
  41static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  42{
  43        *remainder = do_div(dividend, divisor);
  44        return dividend;
  45}
  46#endif
  47
  48#ifndef div_s64_rem
  49extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  50#endif
  51
  52#ifndef div64_u64
  53extern u64 div64_u64(u64 dividend, u64 divisor);
  54#endif
  55
  56#endif /* BITS_PER_LONG */
  57
  58/**
  59 * div_u64 - unsigned 64bit divide with 32bit divisor
  60 *
  61 * This is the most common 64bit divide and should be used if possible,
  62 * as many 32bit archs can optimize this variant better than a full 64bit
  63 * divide.
  64 */
  65#ifndef div_u64
  66static inline u64 div_u64(u64 dividend, u32 divisor)
  67{
  68        u32 remainder;
  69        return div_u64_rem(dividend, divisor, &remainder);
  70}
  71#endif
  72
  73/**
  74 * div_s64 - signed 64bit divide with 32bit divisor
  75 */
  76#ifndef div_s64
  77static inline s64 div_s64(s64 dividend, s32 divisor)
  78{
  79        s32 remainder;
  80        return div_s64_rem(dividend, divisor, &remainder);
  81}
  82#endif
  83
  84u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
  85
  86static __always_inline u32
  87__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
  88{
  89        u32 ret = 0;
  90
  91        while (dividend >= divisor) {
  92                /* The following asm() prevents the compiler from
  93                   optimising this loop into a modulo operation.  */
  94                asm("" : "+rm"(dividend));
  95
  96                dividend -= divisor;
  97                ret++;
  98        }
  99
 100        *remainder = dividend;
 101
 102        return ret;
 103}
 104
 105#endif /* _LINUX_MATH64_H */
 106