include/div64.h

   1 #ifndef _ASM_GENERIC_DIV64_H
   2 #define _ASM_GENERIC_DIV64_H
   3 /*
   4  * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
   5  * Based on former asm-ppc/div64.h and asm-m68knommu/div64.h
   6  *
   7  * The semantics of do_div() are:
   8  *
   9  * uint32_t do_div(uint64_t *n, uint32_t base)
  10  * {
  11  *      uint32_t remainder = *n % base;
  12  *      *n = *n / base;
  13  *      return remainder;
  14  * }
  15  *
  16  * NOTE: macro parameter n is evaluated multiple times,
  17  *       beware of side effects!
  18  */
  19
  20 #include <linux/types.h>
  21
  22 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
  23
  24 /* The unnecessary pointer compare is there
  25  * to check for type safety (n must be 64bit)
  26  */
  27 # define do_div(n,base) ({                              \
  28         uint32_t __base = (base);                       \
  29         uint32_t __rem;                                 \
  30         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
  31         if (((n) >> 32) == 0) {                 \
  32                 __rem = (uint32_t)(n) % __base;         \
  33                 (n) = (uint32_t)(n) / __base;           \
  34         } else                                          \
  35                 __rem = __div64_32(&(n), __base);       \
  36         __rem;                                          \
  37  })
  38
  39 /* Wrapper for do_div(). Doesn't modify dividend and returns
  40  * the result, not reminder.
  41  */
  42 static inline uint64_t lldiv(uint64_t dividend, uint32_t divisor)
  43 {
  44         uint64_t __res = dividend;
  45         do_div(__res, divisor);
  46         return(__res);
  47 }
  48
  49 #endif /* _ASM_GENERIC_DIV64_H */