xref: /openbmc/linux/include/linux/math64.h (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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 /**
10  * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
11  *
12  * This is commonly provided by 32bit archs to provide an optimized 64bit
13  * divide.
14  */
15 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
16 {
17 	*remainder = dividend % divisor;
18 	return dividend / divisor;
19 }
20 
21 /**
22  * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
23  */
24 static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
25 {
26 	*remainder = dividend % divisor;
27 	return dividend / divisor;
28 }
29 
30 /**
31  * div64_u64 - unsigned 64bit divide with 64bit divisor
32  */
33 static inline u64 div64_u64(u64 dividend, u64 divisor)
34 {
35 	return dividend / divisor;
36 }
37 
38 #elif BITS_PER_LONG == 32
39 
40 #ifndef div_u64_rem
41 static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
42 {
43 	*remainder = do_div(dividend, divisor);
44 	return dividend;
45 }
46 #endif
47 
48 #ifndef div_s64_rem
49 extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
50 #endif
51 
52 #ifndef div64_u64
53 extern u64 div64_u64(u64 dividend, u64 divisor);
54 #endif
55 
56 #endif /* BITS_PER_LONG */
57 
58 /**
59  * div_u64 - unsigned 64bit divide with 32bit divisor
60  *
61  * This is the most common 64bit divide and should be used if possible,
62  * as many 32bit archs can optimize this variant better than a full 64bit
63  * divide.
64  */
65 #ifndef div_u64
66 static inline u64 div_u64(u64 dividend, u32 divisor)
67 {
68 	u32 remainder;
69 	return div_u64_rem(dividend, divisor, &remainder);
70 }
71 #endif
72 
73 /**
74  * div_s64 - signed 64bit divide with 32bit divisor
75  */
76 #ifndef div_s64
77 static inline s64 div_s64(s64 dividend, s32 divisor)
78 {
79 	s32 remainder;
80 	return div_s64_rem(dividend, divisor, &remainder);
81 }
82 #endif
83 
84 u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
85 
86 static __always_inline u32
87 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
88 {
89 	u32 ret = 0;
90 
91 	while (dividend >= divisor) {
92 		/* The following asm() prevents the compiler from
93 		   optimising this loop into a modulo operation.  */
94 		asm("" : "+rm"(dividend));
95 
96 		dividend -= divisor;
97 		ret++;
98 	}
99 
100 	*remainder = dividend;
101 
102 	return ret;
103 }
104 
105 #endif /* _LINUX_MATH64_H */
106