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[pohmelfs.git] / include / asm-arm / div64.h
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1 #ifndef __ASM_ARM_DIV64
2 #define __ASM_ARM_DIV64
4 #include <asm/system.h>
6 /*
7 * The semantics of do_div() are:
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 * }
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).
22 #ifdef __ARMEB__
23 #define __xh "r0"
24 #define __xl "r1"
25 #else
26 #define __xl "r0"
27 #define __xh "r1"
28 #endif
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; \
48 #endif