```   1#ifndef _LINUX_MATH64_H
2#define _LINUX_MATH64_H
3
4#include <linux/types.h>
5#include <asm/div64.h>
6
7#if BITS_PER_LONG == 64
8
9#define div64_long(x,y) div64_s64((x),(y))
10
11/**
12 * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
13 *
14 * This is commonly provided by 32bit archs to provide an optimized 64bit
15 * divide.
16 */
17static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
18{
19        *remainder = dividend % divisor;
20        return dividend / divisor;
21}
22
23/**
24 * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
25 */
26static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
27{
28        *remainder = dividend % divisor;
29        return dividend / divisor;
30}
31
32/**
33 * div64_u64 - unsigned 64bit divide with 64bit divisor
34 */
35static inline u64 div64_u64(u64 dividend, u64 divisor)
36{
37        return dividend / divisor;
38}
39
40/**
41 * div64_s64 - signed 64bit divide with 64bit divisor
42 */
43static inline s64 div64_s64(s64 dividend, s64 divisor)
44{
45        return dividend / divisor;
46}
47
48#elif BITS_PER_LONG == 32
49
50#define div64_long(x,y) div_s64((x),(y))
51
52#ifndef div_u64_rem
53static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
54{
55        *remainder = do_div(dividend, divisor);
56        return dividend;
57}
58#endif
59
60#ifndef div_s64_rem
61extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
62#endif
63
64#ifndef div64_u64
65extern u64 div64_u64(u64 dividend, u64 divisor);
66#endif
67
68#ifndef div64_s64
69extern s64 div64_s64(s64 dividend, s64 divisor);
70#endif
71
72#endif /* BITS_PER_LONG */
73
74/**
75 * div_u64 - unsigned 64bit divide with 32bit divisor
76 *
77 * This is the most common 64bit divide and should be used if possible,
78 * as many 32bit archs can optimize this variant better than a full 64bit
79 * divide.
80 */
81#ifndef div_u64
82static inline u64 div_u64(u64 dividend, u32 divisor)
83{
84        u32 remainder;
85        return div_u64_rem(dividend, divisor, &remainder);
86}
87#endif
88
89/**
90 * div_s64 - signed 64bit divide with 32bit divisor
91 */
92#ifndef div_s64
93static inline s64 div_s64(s64 dividend, s32 divisor)
94{
95        s32 remainder;
96        return div_s64_rem(dividend, divisor, &remainder);
97}
98#endif
99
100u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
101
102static __always_inline u32
103__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
104{
105        u32 ret = 0;
106
107        while (dividend >= divisor) {
108                /* The following asm() prevents the compiler from
109                   optimising this loop into a modulo operation.  */
110                asm("" : "+rm"(dividend));
111
112                dividend -= divisor;
113                ret++;
114        }
115
116        *remainder = dividend;
117
118        return ret;
119}
120
121#endif /* _LINUX_MATH64_H */
122```
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