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  */
  15 static 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  */
  24 static 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  */
  33 static 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
  41 static 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
  49 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  50 #endif
  51
  52 #ifndef div64_u64
  53 extern 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
  66 static 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
  77 static inline s64 div_s64(s64 dividend, s32 divisor)
  78 {
  79         s32 remainder;
  80         return div_s64_rem(dividend, divisor, &remainder);
  81 }
  82 #endif
  83
  84 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
  85
  86 static __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 */