linux/include/linux/math64.h
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   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/**
  39 * div64_s64 - signed 64bit divide with 64bit divisor
  40 */
  41static inline s64 div64_s64(s64 dividend, s64 divisor)
  42{
  43        return dividend / divisor;
  44}
  45
  46#elif BITS_PER_LONG == 32
  47
  48#ifndef div_u64_rem
  49static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  50{
  51        *remainder = do_div(dividend, divisor);
  52        return dividend;
  53}
  54#endif
  55
  56#ifndef div_s64_rem
  57extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  58#endif
  59
  60#ifndef div64_u64
  61extern u64 div64_u64(u64 dividend, u64 divisor);
  62#endif
  63
  64#ifndef div64_s64
  65extern s64 div64_s64(s64 dividend, s64 divisor);
  66#endif
  67
  68#endif /* BITS_PER_LONG */
  69
  70/**
  71 * div_u64 - unsigned 64bit divide with 32bit divisor
  72 *
  73 * This is the most common 64bit divide and should be used if possible,
  74 * as many 32bit archs can optimize this variant better than a full 64bit
  75 * divide.
  76 */
  77#ifndef div_u64
  78static inline u64 div_u64(u64 dividend, u32 divisor)
  79{
  80        u32 remainder;
  81        return div_u64_rem(dividend, divisor, &remainder);
  82}
  83#endif
  84
  85/**
  86 * div_s64 - signed 64bit divide with 32bit divisor
  87 */
  88#ifndef div_s64
  89static inline s64 div_s64(s64 dividend, s32 divisor)
  90{
  91        s32 remainder;
  92        return div_s64_rem(dividend, divisor, &remainder);
  93}
  94#endif
  95
  96u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
  97
  98static __always_inline u32
  99__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 100{
 101        u32 ret = 0;
 102
 103        while (dividend >= divisor) {
 104                /* The following asm() prevents the compiler from
 105                   optimising this loop into a modulo operation.  */
 106                asm("" : "+rm"(dividend));
 107
 108                dividend -= divisor;
 109                ret++;
 110        }
 111
 112        *remainder = dividend;
 113
 114        return ret;
 115}
 116
 117#endif /* _LINUX_MATH64_H */
 118