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-rw-r--r--fs/xfs/xfs_bit.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c
index 48228848f5ae..fab0b6d5a41b 100644
--- a/fs/xfs/xfs_bit.c
+++ b/fs/xfs/xfs_bit.c
@@ -25,6 +25,109 @@
25 * XFS bit manipulation routines, used in non-realtime code. 25 * XFS bit manipulation routines, used in non-realtime code.
26 */ 26 */
27 27
28#ifndef HAVE_ARCH_HIGHBIT
29/*
30 * Index of high bit number in byte, -1 for none set, 0..7 otherwise.
31 */
32static const char xfs_highbit[256] = {
33 -1, 0, 1, 1, 2, 2, 2, 2, /* 00 .. 07 */
34 3, 3, 3, 3, 3, 3, 3, 3, /* 08 .. 0f */
35 4, 4, 4, 4, 4, 4, 4, 4, /* 10 .. 17 */
36 4, 4, 4, 4, 4, 4, 4, 4, /* 18 .. 1f */
37 5, 5, 5, 5, 5, 5, 5, 5, /* 20 .. 27 */
38 5, 5, 5, 5, 5, 5, 5, 5, /* 28 .. 2f */
39 5, 5, 5, 5, 5, 5, 5, 5, /* 30 .. 37 */
40 5, 5, 5, 5, 5, 5, 5, 5, /* 38 .. 3f */
41 6, 6, 6, 6, 6, 6, 6, 6, /* 40 .. 47 */
42 6, 6, 6, 6, 6, 6, 6, 6, /* 48 .. 4f */
43 6, 6, 6, 6, 6, 6, 6, 6, /* 50 .. 57 */
44 6, 6, 6, 6, 6, 6, 6, 6, /* 58 .. 5f */
45 6, 6, 6, 6, 6, 6, 6, 6, /* 60 .. 67 */
46 6, 6, 6, 6, 6, 6, 6, 6, /* 68 .. 6f */
47 6, 6, 6, 6, 6, 6, 6, 6, /* 70 .. 77 */
48 6, 6, 6, 6, 6, 6, 6, 6, /* 78 .. 7f */
49 7, 7, 7, 7, 7, 7, 7, 7, /* 80 .. 87 */
50 7, 7, 7, 7, 7, 7, 7, 7, /* 88 .. 8f */
51 7, 7, 7, 7, 7, 7, 7, 7, /* 90 .. 97 */
52 7, 7, 7, 7, 7, 7, 7, 7, /* 98 .. 9f */
53 7, 7, 7, 7, 7, 7, 7, 7, /* a0 .. a7 */
54 7, 7, 7, 7, 7, 7, 7, 7, /* a8 .. af */
55 7, 7, 7, 7, 7, 7, 7, 7, /* b0 .. b7 */
56 7, 7, 7, 7, 7, 7, 7, 7, /* b8 .. bf */
57 7, 7, 7, 7, 7, 7, 7, 7, /* c0 .. c7 */
58 7, 7, 7, 7, 7, 7, 7, 7, /* c8 .. cf */
59 7, 7, 7, 7, 7, 7, 7, 7, /* d0 .. d7 */
60 7, 7, 7, 7, 7, 7, 7, 7, /* d8 .. df */
61 7, 7, 7, 7, 7, 7, 7, 7, /* e0 .. e7 */
62 7, 7, 7, 7, 7, 7, 7, 7, /* e8 .. ef */
63 7, 7, 7, 7, 7, 7, 7, 7, /* f0 .. f7 */
64 7, 7, 7, 7, 7, 7, 7, 7, /* f8 .. ff */
65};
66#endif
67
68/*
69 * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
70 */
71inline int
72xfs_highbit32(
73 __uint32_t v)
74{
75#ifdef HAVE_ARCH_HIGHBIT
76 return highbit32(v);
77#else
78 int i;
79
80 if (v & 0xffff0000)
81 if (v & 0xff000000)
82 i = 24;
83 else
84 i = 16;
85 else if (v & 0x0000ffff)
86 if (v & 0x0000ff00)
87 i = 8;
88 else
89 i = 0;
90 else
91 return -1;
92 return i + xfs_highbit[(v >> i) & 0xff];
93#endif
94}
95
96/*
97 * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set.
98 */
99int
100xfs_lowbit64(
101 __uint64_t v)
102{
103 __uint32_t w = (__uint32_t)v;
104 int n = 0;
105
106 if (w) { /* lower bits */
107 n = ffs(w);
108 } else { /* upper bits */
109 w = (__uint32_t)(v >> 32);
110 if (w && (n = ffs(w)))
111 n += 32;
112 }
113 return n - 1;
114}
115
116/*
117 * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set.
118 */
119int
120xfs_highbit64(
121 __uint64_t v)
122{
123 __uint32_t h = (__uint32_t)(v >> 32);
124
125 if (h)
126 return xfs_highbit32(h) + 32;
127 return xfs_highbit32((__uint32_t)v);
128}
129
130
28/* 131/*
29 * Return whether bitmap is empty. 132 * Return whether bitmap is empty.
30 * Size is number of words in the bitmap, which is padded to word boundary 133 * Size is number of words in the bitmap, which is padded to word boundary