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1/*
2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
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
7 * published by the Free Software Foundation.
8 *
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.
13 *
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
17 */
18#include "xfs.h"
19#include "xfs_log_format.h"
20#include "xfs_bit.h"
21
22/*
23 * XFS bit manipulation routines, used in non-realtime code.
24 */
25
26/*
27 * 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.
30 */
31int
32xfs_bitmap_empty(uint *map, uint size)
33{
34 uint i;
35
36 for (i = 0; i < size; i++) {
37 if (map[i] != 0)
38 return 0;
39 }
40
41 return 1;
42}
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}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
4 * All Rights Reserved.
5 */
6#include "xfs.h"
7#include "xfs_log_format.h"
8
9/*
10 * XFS bit manipulation routines, used in non-realtime code.
11 */
12
13/*
14 * Return whether bitmap is empty.
15 * Size is number of words in the bitmap, which is padded to word boundary
16 * Returns 1 for empty, 0 for non-empty.
17 */
18int
19xfs_bitmap_empty(uint *map, uint size)
20{
21 uint i;
22
23 for (i = 0; i < size; i++) {
24 if (map[i] != 0)
25 return 0;
26 }
27
28 return 1;
29}
30
31/*
32 * Count the number of contiguous bits set in the bitmap starting with bit
33 * start_bit. Size is the size of the bitmap in words.
34 */
35int
36xfs_contig_bits(uint *map, uint size, uint start_bit)
37{
38 uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
39 uint result = 0;
40 uint tmp;
41
42 size <<= BIT_TO_WORD_SHIFT;
43
44 ASSERT(start_bit < size);
45 size -= start_bit & ~(NBWORD - 1);
46 start_bit &= (NBWORD - 1);
47 if (start_bit) {
48 tmp = *p++;
49 /* set to one first offset bits prior to start */
50 tmp |= (~0U >> (NBWORD-start_bit));
51 if (tmp != ~0U)
52 goto found;
53 result += NBWORD;
54 size -= NBWORD;
55 }
56 while (size) {
57 if ((tmp = *p++) != ~0U)
58 goto found;
59 result += NBWORD;
60 size -= NBWORD;
61 }
62 return result - start_bit;
63found:
64 return result + ffz(tmp) - start_bit;
65}
66
67/*
68 * This takes the bit number to start looking from and
69 * returns the next set bit from there. It returns -1
70 * if there are no more bits set or the start bit is
71 * beyond the end of the bitmap.
72 *
73 * Size is the number of words, not bytes, in the bitmap.
74 */
75int xfs_next_bit(uint *map, uint size, uint start_bit)
76{
77 uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
78 uint result = start_bit & ~(NBWORD - 1);
79 uint tmp;
80
81 size <<= BIT_TO_WORD_SHIFT;
82
83 if (start_bit >= size)
84 return -1;
85 size -= result;
86 start_bit &= (NBWORD - 1);
87 if (start_bit) {
88 tmp = *p++;
89 /* set to zero first offset bits prior to start */
90 tmp &= (~0U << start_bit);
91 if (tmp != 0U)
92 goto found;
93 result += NBWORD;
94 size -= NBWORD;
95 }
96 while (size) {
97 if ((tmp = *p++) != 0U)
98 goto found;
99 result += NBWORD;
100 size -= NBWORD;
101 }
102 return -1;
103found:
104 return result + ffs(tmp) - 1;
105}