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 /**
  39  * div64_s64 - signed 64bit divide with 64bit divisor
  40  */
  41 static 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
  49 static 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
  57 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  58 #endif
  59
  60 #ifndef div64_u64
  61 extern u64 div64_u64(u64 dividend, u64 divisor);
  62 #endif
  63
  64 #ifndef div64_s64
  65 extern 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
  78 static 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
  89 static inline s64 div_s64(s64 dividend, s32 divisor)
  90 {
  91         s32 remainder;
  92         return div_s64_rem(dividend, divisor, &remainder);
  93 }
  94 #endif
  95
  96 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
  97
  98 static __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 */