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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Nathan Scott7b718762005-11-02 14:58:39 +11002 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
Nathan Scott7b718762005-11-02 14:58:39 +11005 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 * published by the Free Software Foundation.
8 *
Nathan Scott7b718762005-11-02 14:58:39 +11009 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 *
Nathan Scott7b718762005-11-02 14:58:39 +110014 * 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070017 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include "xfs.h"
Dave Chinner239880e2013-10-23 10:50:10 +110019#include "xfs_log_format.h"
Dave Chinner632b89e2013-10-29 22:11:58 +110020#include "xfs_bit.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Nathan Scott7b718762005-11-02 14:58:39 +110022/*
23 * XFS bit manipulation routines, used in non-realtime code.
24 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
Linus Torvalds1da177e2005-04-16 15:20:36 -070026/*
Eric Sandeen24ad33f2007-06-28 16:43:30 +100027 * Return whether bitmap is empty.
28 * Size is number of words in the bitmap, which is padded to word boundary
29 * Returns 1 for empty, 0 for non-empty.
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 */
31int
Eric Sandeen24ad33f2007-06-28 16:43:30 +100032xfs_bitmap_empty(uint *map, uint size)
Linus Torvalds1da177e2005-04-16 15:20:36 -070033{
Eric Sandeen24ad33f2007-06-28 16:43:30 +100034 uint i;
35 uint ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Eric Sandeen24ad33f2007-06-28 16:43:30 +100037 for (i = 0; i < size; i++) {
38 ret |= map[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 }
40
Eric Sandeen24ad33f2007-06-28 16:43:30 +100041 return (ret == 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070042}
43
44/*
45 * Count the number of contiguous bits set in the bitmap starting with bit
46 * start_bit. Size is the size of the bitmap in words.
47 */
48int
49xfs_contig_bits(uint *map, uint size, uint start_bit)
50{
51 uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
52 uint result = 0;
53 uint tmp;
54
55 size <<= BIT_TO_WORD_SHIFT;
56
57 ASSERT(start_bit < size);
58 size -= start_bit & ~(NBWORD - 1);
59 start_bit &= (NBWORD - 1);
60 if (start_bit) {
61 tmp = *p++;
62 /* set to one first offset bits prior to start */
63 tmp |= (~0U >> (NBWORD-start_bit));
64 if (tmp != ~0U)
65 goto found;
66 result += NBWORD;
67 size -= NBWORD;
68 }
69 while (size) {
70 if ((tmp = *p++) != ~0U)
71 goto found;
72 result += NBWORD;
73 size -= NBWORD;
74 }
75 return result - start_bit;
76found:
77 return result + ffz(tmp) - start_bit;
78}
79
80/*
81 * This takes the bit number to start looking from and
82 * returns the next set bit from there. It returns -1
83 * if there are no more bits set or the start bit is
84 * beyond the end of the bitmap.
85 *
86 * Size is the number of words, not bytes, in the bitmap.
87 */
88int xfs_next_bit(uint *map, uint size, uint start_bit)
89{
90 uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
91 uint result = start_bit & ~(NBWORD - 1);
92 uint tmp;
93
94 size <<= BIT_TO_WORD_SHIFT;
95
96 if (start_bit >= size)
97 return -1;
98 size -= result;
99 start_bit &= (NBWORD - 1);
100 if (start_bit) {
101 tmp = *p++;
102 /* set to zero first offset bits prior to start */
103 tmp &= (~0U << start_bit);
104 if (tmp != 0U)
105 goto found;
106 result += NBWORD;
107 size -= NBWORD;
108 }
109 while (size) {
110 if ((tmp = *p++) != 0U)
111 goto found;
112 result += NBWORD;
113 size -= NBWORD;
114 }
115 return -1;
116found:
117 return result + ffs(tmp) - 1;
118}