Merge master.kernel.org:/home/rmk/linux-2.6-arm
[linux-2.6] / 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