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1da177e4 | 1 | /* |
7b718769 NS |
2 | * Copyright (c) 2000-2005 Silicon Graphics, Inc. |
3 | * All Rights Reserved. | |
1da177e4 | 4 | * |
7b718769 NS |
5 | * This program is free software; you can redistribute it and/or |
6 | * modify it under the terms of the GNU General Public License as | |
1da177e4 LT |
7 | * published by the Free Software Foundation. |
8 | * | |
7b718769 NS |
9 | * This program is distributed in the hope that it would be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
1da177e4 | 13 | * |
7b718769 NS |
14 | * You should have received a copy of the GNU General Public License |
15 | * along with this program; if not, write the Free Software Foundation, | |
16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
1da177e4 | 17 | */ |
1da177e4 LT |
18 | #include "xfs.h" |
19 | #include "xfs_bit.h" | |
20 | #include "xfs_log.h" | |
21 | #include "xfs_trans.h" | |
22 | #include "xfs_buf_item.h" | |
23 | ||
7b718769 NS |
24 | /* |
25 | * XFS bit manipulation routines, used in non-realtime code. | |
26 | */ | |
1da177e4 LT |
27 | |
28 | #ifndef HAVE_ARCH_HIGHBIT | |
29 | /* | |
30 | * Index of high bit number in byte, -1 for none set, 0..7 otherwise. | |
31 | */ | |
7989cb8e | 32 | static const char xfs_highbit[256] = { |
1da177e4 LT |
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 | ||
1da177e4 LT |
68 | /* |
69 | * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set. | |
70 | */ | |
71 | inline int | |
72 | xfs_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 | */ | |
99 | int | |
100 | xfs_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 | */ | |
119 | int | |
120 | xfs_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 | ||
131 | /* | |
24ad33ff ES |
132 | * Return whether bitmap is empty. |
133 | * Size is number of words in the bitmap, which is padded to word boundary | |
134 | * Returns 1 for empty, 0 for non-empty. | |
1da177e4 LT |
135 | */ |
136 | int | |
24ad33ff | 137 | xfs_bitmap_empty(uint *map, uint size) |
1da177e4 | 138 | { |
24ad33ff ES |
139 | uint i; |
140 | uint ret = 0; | |
1da177e4 | 141 | |
24ad33ff ES |
142 | for (i = 0; i < size; i++) { |
143 | ret |= map[i]; | |
1da177e4 LT |
144 | } |
145 | ||
24ad33ff | 146 | return (ret == 0); |
1da177e4 LT |
147 | } |
148 | ||
149 | /* | |
150 | * Count the number of contiguous bits set in the bitmap starting with bit | |
151 | * start_bit. Size is the size of the bitmap in words. | |
152 | */ | |
153 | int | |
154 | xfs_contig_bits(uint *map, uint size, uint start_bit) | |
155 | { | |
156 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
157 | uint result = 0; | |
158 | uint tmp; | |
159 | ||
160 | size <<= BIT_TO_WORD_SHIFT; | |
161 | ||
162 | ASSERT(start_bit < size); | |
163 | size -= start_bit & ~(NBWORD - 1); | |
164 | start_bit &= (NBWORD - 1); | |
165 | if (start_bit) { | |
166 | tmp = *p++; | |
167 | /* set to one first offset bits prior to start */ | |
168 | tmp |= (~0U >> (NBWORD-start_bit)); | |
169 | if (tmp != ~0U) | |
170 | goto found; | |
171 | result += NBWORD; | |
172 | size -= NBWORD; | |
173 | } | |
174 | while (size) { | |
175 | if ((tmp = *p++) != ~0U) | |
176 | goto found; | |
177 | result += NBWORD; | |
178 | size -= NBWORD; | |
179 | } | |
180 | return result - start_bit; | |
181 | found: | |
182 | return result + ffz(tmp) - start_bit; | |
183 | } | |
184 | ||
185 | /* | |
186 | * This takes the bit number to start looking from and | |
187 | * returns the next set bit from there. It returns -1 | |
188 | * if there are no more bits set or the start bit is | |
189 | * beyond the end of the bitmap. | |
190 | * | |
191 | * Size is the number of words, not bytes, in the bitmap. | |
192 | */ | |
193 | int xfs_next_bit(uint *map, uint size, uint start_bit) | |
194 | { | |
195 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
196 | uint result = start_bit & ~(NBWORD - 1); | |
197 | uint tmp; | |
198 | ||
199 | size <<= BIT_TO_WORD_SHIFT; | |
200 | ||
201 | if (start_bit >= size) | |
202 | return -1; | |
203 | size -= result; | |
204 | start_bit &= (NBWORD - 1); | |
205 | if (start_bit) { | |
206 | tmp = *p++; | |
207 | /* set to zero first offset bits prior to start */ | |
208 | tmp &= (~0U << start_bit); | |
209 | if (tmp != 0U) | |
210 | goto found; | |
211 | result += NBWORD; | |
212 | size -= NBWORD; | |
213 | } | |
214 | while (size) { | |
215 | if ((tmp = *p++) != 0U) | |
216 | goto found; | |
217 | result += NBWORD; | |
218 | size -= NBWORD; | |
219 | } | |
220 | return -1; | |
221 | found: | |
222 | return result + ffs(tmp) - 1; | |
223 | } |