Linux kernel mirror (for testing)
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1#ifndef _LINUX_BITOPS_H
2#define _LINUX_BITOPS_H
3#include <asm/types.h>
4
5/*
6 * ffs: find first bit set. This is defined the same way as
7 * the libc and compiler builtin ffs routines, therefore
8 * differs in spirit from the above ffz (man ffs).
9 */
10
11static inline int generic_ffs(int x)
12{
13 int r = 1;
14
15 if (!x)
16 return 0;
17 if (!(x & 0xffff)) {
18 x >>= 16;
19 r += 16;
20 }
21 if (!(x & 0xff)) {
22 x >>= 8;
23 r += 8;
24 }
25 if (!(x & 0xf)) {
26 x >>= 4;
27 r += 4;
28 }
29 if (!(x & 3)) {
30 x >>= 2;
31 r += 2;
32 }
33 if (!(x & 1)) {
34 x >>= 1;
35 r += 1;
36 }
37 return r;
38}
39
40/*
41 * fls: find last bit set.
42 */
43
44static __inline__ int generic_fls(int x)
45{
46 int r = 32;
47
48 if (!x)
49 return 0;
50 if (!(x & 0xffff0000u)) {
51 x <<= 16;
52 r -= 16;
53 }
54 if (!(x & 0xff000000u)) {
55 x <<= 8;
56 r -= 8;
57 }
58 if (!(x & 0xf0000000u)) {
59 x <<= 4;
60 r -= 4;
61 }
62 if (!(x & 0xc0000000u)) {
63 x <<= 2;
64 r -= 2;
65 }
66 if (!(x & 0x80000000u)) {
67 x <<= 1;
68 r -= 1;
69 }
70 return r;
71}
72
73/*
74 * Include this here because some architectures need generic_ffs/fls in
75 * scope
76 */
77#include <asm/bitops.h>
78
79static __inline__ int get_bitmask_order(unsigned int count)
80{
81 int order;
82
83 order = fls(count);
84 return order; /* We could be slightly more clever with -1 here... */
85}
86
87static __inline__ int get_count_order(unsigned int count)
88{
89 int order;
90
91 order = fls(count) - 1;
92 if (count & (count - 1))
93 order++;
94 return order;
95}
96
97/*
98 * hweightN: returns the hamming weight (i.e. the number
99 * of bits set) of a N-bit word
100 */
101
102static inline unsigned int generic_hweight32(unsigned int w)
103{
104 unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
105 res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
106 res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
107 res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
108 return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
109}
110
111static inline unsigned int generic_hweight16(unsigned int w)
112{
113 unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
114 res = (res & 0x3333) + ((res >> 2) & 0x3333);
115 res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
116 return (res & 0x00FF) + ((res >> 8) & 0x00FF);
117}
118
119static inline unsigned int generic_hweight8(unsigned int w)
120{
121 unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
122 res = (res & 0x33) + ((res >> 2) & 0x33);
123 return (res & 0x0F) + ((res >> 4) & 0x0F);
124}
125
126static inline unsigned long generic_hweight64(__u64 w)
127{
128#if BITS_PER_LONG < 64
129 return generic_hweight32((unsigned int)(w >> 32)) +
130 generic_hweight32((unsigned int)w);
131#else
132 u64 res;
133 res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul);
134 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
135 res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful);
136 res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul);
137 res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul);
138 return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul);
139#endif
140}
141
142static inline unsigned long hweight_long(unsigned long w)
143{
144 return sizeof(w) == 4 ? generic_hweight32(w) : generic_hweight64(w);
145}
146
147/*
148 * rol32 - rotate a 32-bit value left
149 *
150 * @word: value to rotate
151 * @shift: bits to roll
152 */
153static inline __u32 rol32(__u32 word, unsigned int shift)
154{
155 return (word << shift) | (word >> (32 - shift));
156}
157
158/*
159 * ror32 - rotate a 32-bit value right
160 *
161 * @word: value to rotate
162 * @shift: bits to roll
163 */
164static inline __u32 ror32(__u32 word, unsigned int shift)
165{
166 return (word >> shift) | (word << (32 - shift));
167}
168
169#endif