include/asm-generic/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 #include <linux/compiler.h>
  22
  23 #if BITS_PER_LONG == 64
  24
  25 # define do_div(n,base) ({                                      \
  26         uint32_t __base = (base);                               \
  27         uint32_t __rem;                                         \
  28         __rem = ((uint64_t)(n)) % __base;                       \
  29         (n) = ((uint64_t)(n)) / __base;                         \
  30         __rem;                                                  \
  31  })
  32
  33 #elif BITS_PER_LONG == 32
  34
  35 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
  36
  37 /* The unnecessary pointer compare is there
  38  * to check for type safety (n must be 64bit)
  39  */
  40 # define do_div(n,base) ({                              \
  41         uint32_t __base = (base);                       \
  42         uint32_t __rem;                                 \
  43         (void)(((typeof((n)) *)0) == ((uint64_t *)0));  \
  44         if (likely(((n) >> 32) == 0)) {                 \
  45                 __rem = (uint32_t)(n) % __base;         \
  46                 (n) = (uint32_t)(n) / __base;           \
  47         } else                                          \
  48                 __rem = __div64_32(&(n), __base);       \
  49         __rem;                                          \
  50  })
  51
  52 #else /* BITS_PER_LONG == ?? */
  53
  54 # error do_div() does not yet support the C64
  55
  56 #endif /* BITS_PER_LONG */
  57
  58 #endif /* _ASM_GENERIC_DIV64_H */