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#define div64_long(x,y) div64_s64((x),(y))
  10
  11/**
  12 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
  13 *
  14 * This is commonly provided by 32bit archs to provide an optimized 64bit
  15 * divide.
  16 */
  17static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  18{
  19        *remainder = dividend % divisor;
  20        return dividend / divisor;
  21}
  22
  23/**
  24 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
  25 */
  26static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
  27{
  28        *remainder = dividend % divisor;
  29        return dividend / divisor;
  30}
  31
  32/**
  33 * div64_u64 - unsigned 64bit divide with 64bit divisor
  34 */
  35static inline u64 div64_u64(u64 dividend, u64 divisor)
  36{
  37        return dividend / divisor;
  38}
  39
  40/**
  41 * div64_s64 - signed 64bit divide with 64bit divisor
  42 */
  43static inline s64 div64_s64(s64 dividend, s64 divisor)
  44{
  45        return dividend / divisor;
  46}
  47
  48#elif BITS_PER_LONG == 32
  49
  50#define div64_long(x,y) div_s64((x),(y))
  51
  52#ifndef div_u64_rem
  53static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  54{
  55        *remainder = do_div(dividend, divisor);
  56        return dividend;
  57}
  58#endif
  59
  60#ifndef div_s64_rem
  61extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  62#endif
  63
  64#ifndef div64_u64
  65extern u64 div64_u64(u64 dividend, u64 divisor);
  66#endif
  67
  68#ifndef div64_s64
  69extern s64 div64_s64(s64 dividend, s64 divisor);
  70#endif
  71
  72#endif /* BITS_PER_LONG */
  73
  74/**
  75 * div_u64 - unsigned 64bit divide with 32bit divisor
  76 *
  77 * This is the most common 64bit divide and should be used if possible,
  78 * as many 32bit archs can optimize this variant better than a full 64bit
  79 * divide.
  80 */
  81#ifndef div_u64
  82static inline u64 div_u64(u64 dividend, u32 divisor)
  83{
  84        u32 remainder;
  85        return div_u64_rem(dividend, divisor, &remainder);
  86}
  87#endif
  88
  89/**
  90 * div_s64 - signed 64bit divide with 32bit divisor
  91 */
  92#ifndef div_s64
  93static inline s64 div_s64(s64 dividend, s32 divisor)
  94{
  95        s32 remainder;
  96        return div_s64_rem(dividend, divisor, &remainder);
  97}
  98#endif
  99
 100u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
 101
 102static __always_inline u32
 103__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 104{
 105        u32 ret = 0;
 106
 107        while (dividend >= divisor) {
 108                /* The following asm() prevents the compiler from
 109                   optimising this loop into a modulo operation.  */
 110                asm("" : "+rm"(dividend));
 111
 112                dividend -= divisor;
 113                ret++;
 114        }
 115
 116        *remainder = dividend;
 117
 118        return ret;
 119}
 120
 121#endif /* _LINUX_MATH64_H */
 122