include/asm-arm/div64.h

   1 #ifndef __ASM_ARM_DIV64
   2 #define __ASM_ARM_DIV64
   3
   4 #include <asm/system.h>
   5
   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  * In other words, a 64-bit dividend with a 32-bit divisor producing
  17  * a 64-bit result and a 32-bit remainder.  To accomplish this optimally
  18  * we call a special __do_div64 helper with completely non standard
  19  * calling convention for arguments and results (beware).
  20  */
  21
  22 #ifdef __ARMEB__
  23 #define __xh "r0"
  24 #define __xl "r1"
  25 #else
  26 #define __xl "r0"
  27 #define __xh "r1"
  28 #endif
  29
  30 #define do_div(n,base)                                          \
  31 ({                                                              \
  32         register unsigned int __base      asm("r4") = base;     \
  33         register unsigned long long __n   asm("r0") = n;        \
  34         register unsigned long long __res asm("r2");            \
  35         register unsigned int __rem       asm(__xh);            \
  36         asm(    __asmeq("%0", __xh)                             \
  37                 __asmeq("%1", "r2")                             \
  38                 __asmeq("%2", "r0")                             \
  39                 __asmeq("%3", "r4")                             \
  40                 "bl     __do_div64"                             \
  41                 : "=r" (__rem), "=r" (__res)                    \
  42                 : "r" (__n), "r" (__base)                       \
  43                 : "ip", "lr", "cc");                            \
  44         n = __res;                                              \
  45         __rem;                                                  \
  46 })
  47
  48 #endif