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1da177e4 LT |
1 | /* |
2 | * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify it | |
5 | * under the terms of version 2 of the GNU General Public License as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it would be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | |
11 | * | |
12 | * Further, this software is distributed without any warranty that it is | |
13 | * free of the rightful claim of any third person regarding infringement | |
14 | * or the like. Any license provided herein, whether implied or | |
15 | * otherwise, applies only to this software file. Patent licenses, if | |
16 | * any, provided herein do not apply to combinations of this program with | |
17 | * other software, or any other product whatsoever. | |
18 | * | |
19 | * You should have received a copy of the GNU General Public License along | |
20 | * with this program; if not, write the Free Software Foundation, Inc., 59 | |
21 | * Temple Place - Suite 330, Boston MA 02111-1307, USA. | |
22 | * | |
23 | * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy, | |
24 | * Mountain View, CA 94043, or: | |
25 | * | |
26 | * http://www.sgi.com | |
27 | * | |
28 | * For further information regarding this notice, see: | |
29 | * | |
30 | * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/ | |
31 | */ | |
32 | ||
33 | /* | |
34 | * XFS bit manipulation routines, used in non-realtime code. | |
35 | */ | |
36 | ||
37 | #include "xfs.h" | |
38 | #include "xfs_bit.h" | |
39 | #include "xfs_log.h" | |
40 | #include "xfs_trans.h" | |
41 | #include "xfs_buf_item.h" | |
42 | ||
43 | ||
44 | #ifndef HAVE_ARCH_HIGHBIT | |
45 | /* | |
46 | * Index of high bit number in byte, -1 for none set, 0..7 otherwise. | |
47 | */ | |
ba0f32d4 | 48 | STATIC const char xfs_highbit[256] = { |
1da177e4 LT |
49 | -1, 0, 1, 1, 2, 2, 2, 2, /* 00 .. 07 */ |
50 | 3, 3, 3, 3, 3, 3, 3, 3, /* 08 .. 0f */ | |
51 | 4, 4, 4, 4, 4, 4, 4, 4, /* 10 .. 17 */ | |
52 | 4, 4, 4, 4, 4, 4, 4, 4, /* 18 .. 1f */ | |
53 | 5, 5, 5, 5, 5, 5, 5, 5, /* 20 .. 27 */ | |
54 | 5, 5, 5, 5, 5, 5, 5, 5, /* 28 .. 2f */ | |
55 | 5, 5, 5, 5, 5, 5, 5, 5, /* 30 .. 37 */ | |
56 | 5, 5, 5, 5, 5, 5, 5, 5, /* 38 .. 3f */ | |
57 | 6, 6, 6, 6, 6, 6, 6, 6, /* 40 .. 47 */ | |
58 | 6, 6, 6, 6, 6, 6, 6, 6, /* 48 .. 4f */ | |
59 | 6, 6, 6, 6, 6, 6, 6, 6, /* 50 .. 57 */ | |
60 | 6, 6, 6, 6, 6, 6, 6, 6, /* 58 .. 5f */ | |
61 | 6, 6, 6, 6, 6, 6, 6, 6, /* 60 .. 67 */ | |
62 | 6, 6, 6, 6, 6, 6, 6, 6, /* 68 .. 6f */ | |
63 | 6, 6, 6, 6, 6, 6, 6, 6, /* 70 .. 77 */ | |
64 | 6, 6, 6, 6, 6, 6, 6, 6, /* 78 .. 7f */ | |
65 | 7, 7, 7, 7, 7, 7, 7, 7, /* 80 .. 87 */ | |
66 | 7, 7, 7, 7, 7, 7, 7, 7, /* 88 .. 8f */ | |
67 | 7, 7, 7, 7, 7, 7, 7, 7, /* 90 .. 97 */ | |
68 | 7, 7, 7, 7, 7, 7, 7, 7, /* 98 .. 9f */ | |
69 | 7, 7, 7, 7, 7, 7, 7, 7, /* a0 .. a7 */ | |
70 | 7, 7, 7, 7, 7, 7, 7, 7, /* a8 .. af */ | |
71 | 7, 7, 7, 7, 7, 7, 7, 7, /* b0 .. b7 */ | |
72 | 7, 7, 7, 7, 7, 7, 7, 7, /* b8 .. bf */ | |
73 | 7, 7, 7, 7, 7, 7, 7, 7, /* c0 .. c7 */ | |
74 | 7, 7, 7, 7, 7, 7, 7, 7, /* c8 .. cf */ | |
75 | 7, 7, 7, 7, 7, 7, 7, 7, /* d0 .. d7 */ | |
76 | 7, 7, 7, 7, 7, 7, 7, 7, /* d8 .. df */ | |
77 | 7, 7, 7, 7, 7, 7, 7, 7, /* e0 .. e7 */ | |
78 | 7, 7, 7, 7, 7, 7, 7, 7, /* e8 .. ef */ | |
79 | 7, 7, 7, 7, 7, 7, 7, 7, /* f0 .. f7 */ | |
80 | 7, 7, 7, 7, 7, 7, 7, 7, /* f8 .. ff */ | |
81 | }; | |
82 | #endif | |
83 | ||
84 | /* | |
85 | * Count of bits set in byte, 0..8. | |
86 | */ | |
87 | static const char xfs_countbit[256] = { | |
88 | 0, 1, 1, 2, 1, 2, 2, 3, /* 00 .. 07 */ | |
89 | 1, 2, 2, 3, 2, 3, 3, 4, /* 08 .. 0f */ | |
90 | 1, 2, 2, 3, 2, 3, 3, 4, /* 10 .. 17 */ | |
91 | 2, 3, 3, 4, 3, 4, 4, 5, /* 18 .. 1f */ | |
92 | 1, 2, 2, 3, 2, 3, 3, 4, /* 20 .. 27 */ | |
93 | 2, 3, 3, 4, 3, 4, 4, 5, /* 28 .. 2f */ | |
94 | 2, 3, 3, 4, 3, 4, 4, 5, /* 30 .. 37 */ | |
95 | 3, 4, 4, 5, 4, 5, 5, 6, /* 38 .. 3f */ | |
96 | 1, 2, 2, 3, 2, 3, 3, 4, /* 40 .. 47 */ | |
97 | 2, 3, 3, 4, 3, 4, 4, 5, /* 48 .. 4f */ | |
98 | 2, 3, 3, 4, 3, 4, 4, 5, /* 50 .. 57 */ | |
99 | 3, 4, 4, 5, 4, 5, 5, 6, /* 58 .. 5f */ | |
100 | 2, 3, 3, 4, 3, 4, 4, 5, /* 60 .. 67 */ | |
101 | 3, 4, 4, 5, 4, 5, 5, 6, /* 68 .. 6f */ | |
102 | 3, 4, 4, 5, 4, 5, 5, 6, /* 70 .. 77 */ | |
103 | 4, 5, 5, 6, 5, 6, 6, 7, /* 78 .. 7f */ | |
104 | 1, 2, 2, 3, 2, 3, 3, 4, /* 80 .. 87 */ | |
105 | 2, 3, 3, 4, 3, 4, 4, 5, /* 88 .. 8f */ | |
106 | 2, 3, 3, 4, 3, 4, 4, 5, /* 90 .. 97 */ | |
107 | 3, 4, 4, 5, 4, 5, 5, 6, /* 98 .. 9f */ | |
108 | 2, 3, 3, 4, 3, 4, 4, 5, /* a0 .. a7 */ | |
109 | 3, 4, 4, 5, 4, 5, 5, 6, /* a8 .. af */ | |
110 | 3, 4, 4, 5, 4, 5, 5, 6, /* b0 .. b7 */ | |
111 | 4, 5, 5, 6, 5, 6, 6, 7, /* b8 .. bf */ | |
112 | 2, 3, 3, 4, 3, 4, 4, 5, /* c0 .. c7 */ | |
113 | 3, 4, 4, 5, 4, 5, 5, 6, /* c8 .. cf */ | |
114 | 3, 4, 4, 5, 4, 5, 5, 6, /* d0 .. d7 */ | |
115 | 4, 5, 5, 6, 5, 6, 6, 7, /* d8 .. df */ | |
116 | 3, 4, 4, 5, 4, 5, 5, 6, /* e0 .. e7 */ | |
117 | 4, 5, 5, 6, 5, 6, 6, 7, /* e8 .. ef */ | |
118 | 4, 5, 5, 6, 5, 6, 6, 7, /* f0 .. f7 */ | |
119 | 5, 6, 6, 7, 6, 7, 7, 8, /* f8 .. ff */ | |
120 | }; | |
121 | ||
122 | /* | |
123 | * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set. | |
124 | */ | |
125 | inline int | |
126 | xfs_highbit32( | |
127 | __uint32_t v) | |
128 | { | |
129 | #ifdef HAVE_ARCH_HIGHBIT | |
130 | return highbit32(v); | |
131 | #else | |
132 | int i; | |
133 | ||
134 | if (v & 0xffff0000) | |
135 | if (v & 0xff000000) | |
136 | i = 24; | |
137 | else | |
138 | i = 16; | |
139 | else if (v & 0x0000ffff) | |
140 | if (v & 0x0000ff00) | |
141 | i = 8; | |
142 | else | |
143 | i = 0; | |
144 | else | |
145 | return -1; | |
146 | return i + xfs_highbit[(v >> i) & 0xff]; | |
147 | #endif | |
148 | } | |
149 | ||
150 | /* | |
151 | * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set. | |
152 | */ | |
153 | int | |
154 | xfs_lowbit64( | |
155 | __uint64_t v) | |
156 | { | |
157 | __uint32_t w = (__uint32_t)v; | |
158 | int n = 0; | |
159 | ||
160 | if (w) { /* lower bits */ | |
161 | n = ffs(w); | |
162 | } else { /* upper bits */ | |
163 | w = (__uint32_t)(v >> 32); | |
164 | if (w && (n = ffs(w))) | |
165 | n += 32; | |
166 | } | |
167 | return n - 1; | |
168 | } | |
169 | ||
170 | /* | |
171 | * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set. | |
172 | */ | |
173 | int | |
174 | xfs_highbit64( | |
175 | __uint64_t v) | |
176 | { | |
177 | __uint32_t h = (__uint32_t)(v >> 32); | |
178 | ||
179 | if (h) | |
180 | return xfs_highbit32(h) + 32; | |
181 | return xfs_highbit32((__uint32_t)v); | |
182 | } | |
183 | ||
184 | ||
185 | /* | |
186 | * Count the number of bits set in the bitmap starting with bit | |
187 | * start_bit. Size is the size of the bitmap in words. | |
188 | * | |
189 | * Do the counting by mapping a byte value to the number of set | |
190 | * bits for that value using the xfs_countbit array, i.e. | |
191 | * xfs_countbit[0] == 0, xfs_countbit[1] == 1, xfs_countbit[2] == 1, | |
192 | * xfs_countbit[3] == 2, etc. | |
193 | */ | |
194 | int | |
195 | xfs_count_bits(uint *map, uint size, uint start_bit) | |
196 | { | |
197 | register int bits; | |
198 | register unsigned char *bytep; | |
199 | register unsigned char *end_map; | |
200 | int byte_bit; | |
201 | ||
202 | bits = 0; | |
203 | end_map = (char*)(map + size); | |
204 | bytep = (char*)(map + (start_bit & ~0x7)); | |
205 | byte_bit = start_bit & 0x7; | |
206 | ||
207 | /* | |
208 | * If the caller fell off the end of the map, return 0. | |
209 | */ | |
210 | if (bytep >= end_map) { | |
211 | return (0); | |
212 | } | |
213 | ||
214 | /* | |
215 | * If start_bit is not byte aligned, then process the | |
216 | * first byte separately. | |
217 | */ | |
218 | if (byte_bit != 0) { | |
219 | /* | |
220 | * Shift off the bits we don't want to look at, | |
221 | * before indexing into xfs_countbit. | |
222 | */ | |
223 | bits += xfs_countbit[(*bytep >> byte_bit)]; | |
224 | bytep++; | |
225 | } | |
226 | ||
227 | /* | |
228 | * Count the bits in each byte until the end of the bitmap. | |
229 | */ | |
230 | while (bytep < end_map) { | |
231 | bits += xfs_countbit[*bytep]; | |
232 | bytep++; | |
233 | } | |
234 | ||
235 | return (bits); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Count the number of contiguous bits set in the bitmap starting with bit | |
240 | * start_bit. Size is the size of the bitmap in words. | |
241 | */ | |
242 | int | |
243 | xfs_contig_bits(uint *map, uint size, uint start_bit) | |
244 | { | |
245 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
246 | uint result = 0; | |
247 | uint tmp; | |
248 | ||
249 | size <<= BIT_TO_WORD_SHIFT; | |
250 | ||
251 | ASSERT(start_bit < size); | |
252 | size -= start_bit & ~(NBWORD - 1); | |
253 | start_bit &= (NBWORD - 1); | |
254 | if (start_bit) { | |
255 | tmp = *p++; | |
256 | /* set to one first offset bits prior to start */ | |
257 | tmp |= (~0U >> (NBWORD-start_bit)); | |
258 | if (tmp != ~0U) | |
259 | goto found; | |
260 | result += NBWORD; | |
261 | size -= NBWORD; | |
262 | } | |
263 | while (size) { | |
264 | if ((tmp = *p++) != ~0U) | |
265 | goto found; | |
266 | result += NBWORD; | |
267 | size -= NBWORD; | |
268 | } | |
269 | return result - start_bit; | |
270 | found: | |
271 | return result + ffz(tmp) - start_bit; | |
272 | } | |
273 | ||
274 | /* | |
275 | * This takes the bit number to start looking from and | |
276 | * returns the next set bit from there. It returns -1 | |
277 | * if there are no more bits set or the start bit is | |
278 | * beyond the end of the bitmap. | |
279 | * | |
280 | * Size is the number of words, not bytes, in the bitmap. | |
281 | */ | |
282 | int xfs_next_bit(uint *map, uint size, uint start_bit) | |
283 | { | |
284 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
285 | uint result = start_bit & ~(NBWORD - 1); | |
286 | uint tmp; | |
287 | ||
288 | size <<= BIT_TO_WORD_SHIFT; | |
289 | ||
290 | if (start_bit >= size) | |
291 | return -1; | |
292 | size -= result; | |
293 | start_bit &= (NBWORD - 1); | |
294 | if (start_bit) { | |
295 | tmp = *p++; | |
296 | /* set to zero first offset bits prior to start */ | |
297 | tmp &= (~0U << start_bit); | |
298 | if (tmp != 0U) | |
299 | goto found; | |
300 | result += NBWORD; | |
301 | size -= NBWORD; | |
302 | } | |
303 | while (size) { | |
304 | if ((tmp = *p++) != 0U) | |
305 | goto found; | |
306 | result += NBWORD; | |
307 | size -= NBWORD; | |
308 | } | |
309 | return -1; | |
310 | found: | |
311 | return result + ffs(tmp) - 1; | |
312 | } |