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 #define div64_ul(x, y)   div64_u64((x), (y))
  11
  12 /**
  13  * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
  14  *
  15  * This is commonly provided by 32bit archs to provide an optimized 64bit
  16  * divide.
  17  */
  18 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  19 {
  20         *remainder = dividend % divisor;
  21         return dividend / divisor;
  22 }
  23
  24 /**
  25  * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
  26  */
  27 static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
  28 {
  29         *remainder = dividend % divisor;
  30         return dividend / divisor;
  31 }
  32
  33 /**
  34  * div64_u64 - unsigned 64bit divide with 64bit divisor
  35  */
  36 static inline u64 div64_u64(u64 dividend, u64 divisor)
  37 {
  38         return dividend / divisor;
  39 }
  40
  41 /**
  42  * div64_s64 - signed 64bit divide with 64bit divisor
  43  */
  44 static inline s64 div64_s64(s64 dividend, s64 divisor)
  45 {
  46         return dividend / divisor;
  47 }
  48
  49 #elif BITS_PER_LONG == 32
  50
  51 #define div64_long(x, y) div_s64((x), (y))
  52 #define div64_ul(x, y)   div_u64((x), (y))
  53
  54 #ifndef div_u64_rem
  55 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
  56 {
  57         *remainder = do_div(dividend, divisor);
  58         return dividend;
  59 }
  60 #endif
  61
  62 #ifndef div_s64_rem
  63 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
  64 #endif
  65
  66 #ifndef div64_u64
  67 extern u64 div64_u64(u64 dividend, u64 divisor);
  68 #endif
  69
  70 #ifndef div64_s64
  71 extern s64 div64_s64(s64 dividend, s64 divisor);
  72 #endif
  73
  74 #endif /* BITS_PER_LONG */
  75
  76 /**
  77  * div_u64 - unsigned 64bit divide with 32bit divisor
  78  *
  79  * This is the most common 64bit divide and should be used if possible,
  80  * as many 32bit archs can optimize this variant better than a full 64bit
  81  * divide.
  82  */
  83 #ifndef div_u64
  84 static inline u64 div_u64(u64 dividend, u32 divisor)
  85 {
  86         u32 remainder;
  87         return div_u64_rem(dividend, divisor, &remainder);
  88 }
  89 #endif
  90
  91 /**
  92  * div_s64 - signed 64bit divide with 32bit divisor
  93  */
  94 #ifndef div_s64
  95 static inline s64 div_s64(s64 dividend, s32 divisor)
  96 {
  97         s32 remainder;
  98         return div_s64_rem(dividend, divisor, &remainder);
  99 }
 100 #endif
 101
 102 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
 103
 104 static __always_inline u32
 105 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 106 {
 107         u32 ret = 0;
 108
 109         while (dividend >= divisor) {
 110                 /* The following asm() prevents the compiler from
 111                    optimising this loop into a modulo operation.  */
 112                 asm("" : "+rm"(dividend));
 113
 114                 dividend -= divisor;
 115                 ret++;
 116         }
 117
 118         *remainder = dividend;
 119
 120         return ret;
 121 }
 122
 123 #endif /* _LINUX_MATH64_H */