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div64.h
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1 #ifndef _ASM_GENERIC_DIV64_H
2 #define _ASM_GENERIC_DIV64_H
3 /*
4  * Copyright (C) 2003 Bernardo Innocenti <[email protected]>
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 */