projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 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 | 27 | |
| 1da177e4 | 28 | /* |
| 24ad33ff ES |
29 | * Return whether bitmap is empty. |
| 30 | * Size is number of words in the bitmap, which is padded to word boundary | |
| 31 | * Returns 1 for empty, 0 for non-empty. | |
| 1da177e4 LT |
32 | */ |
| 33 | int | |
| 24ad33ff | 34 | xfs_bitmap_empty(uint *map, uint size) |
| 1da177e4 | 35 | { |
| 24ad33ff ES |
36 | uint i; |
| 37 | uint ret = 0; | |
| 1da177e4 | 38 | |
| 24ad33ff ES |
39 | for (i = 0; i < size; i++) { |
| 40 | ret |= map[i]; | |
| 1da177e4 LT |
41 | } |
| 42 | ||
| 24ad33ff | 43 | return (ret == 0); |
| 1da177e4 LT |
44 | } |
| 45 | ||
| 46 | /* | |
| 47 | * Count the number of contiguous bits set in the bitmap starting with bit | |
| 48 | * start_bit. Size is the size of the bitmap in words. | |
| 49 | */ | |
| 50 | int | |
| 51 | xfs_contig_bits(uint *map, uint size, uint start_bit) | |
| 52 | { | |
| 53 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
| 54 | uint result = 0; | |
| 55 | uint tmp; | |
| 56 | ||
| 57 | size <<= BIT_TO_WORD_SHIFT; | |
| 58 | ||
| 59 | ASSERT(start_bit < size); | |
| 60 | size -= start_bit & ~(NBWORD - 1); | |
| 61 | start_bit &= (NBWORD - 1); | |
| 62 | if (start_bit) { | |
| 63 | tmp = *p++; | |
| 64 | /* set to one first offset bits prior to start */ | |
| 65 | tmp |= (~0U >> (NBWORD-start_bit)); | |
| 66 | if (tmp != ~0U) | |
| 67 | goto found; | |
| 68 | result += NBWORD; | |
| 69 | size -= NBWORD; | |
| 70 | } | |
| 71 | while (size) { | |
| 72 | if ((tmp = *p++) != ~0U) | |
| 73 | goto found; | |
| 74 | result += NBWORD; | |
| 75 | size -= NBWORD; | |
| 76 | } | |
| 77 | return result - start_bit; | |
| 78 | found: | |
| 79 | return result + ffz(tmp) - start_bit; | |
| 80 | } | |
| 81 | ||
| 82 | /* | |
| 83 | * This takes the bit number to start looking from and | |
| 84 | * returns the next set bit from there. It returns -1 | |
| 85 | * if there are no more bits set or the start bit is | |
| 86 | * beyond the end of the bitmap. | |
| 87 | * | |
| 88 | * Size is the number of words, not bytes, in the bitmap. | |
| 89 | */ | |
| 90 | int xfs_next_bit(uint *map, uint size, uint start_bit) | |
| 91 | { | |
| 92 | uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); | |
| 93 | uint result = start_bit & ~(NBWORD - 1); | |
| 94 | uint tmp; | |
| 95 | ||
| 96 | size <<= BIT_TO_WORD_SHIFT; | |
| 97 | ||
| 98 | if (start_bit >= size) | |
| 99 | return -1; | |
| 100 | size -= result; | |
| 101 | start_bit &= (NBWORD - 1); | |
| 102 | if (start_bit) { | |
| 103 | tmp = *p++; | |
| 104 | /* set to zero first offset bits prior to start */ | |
| 105 | tmp &= (~0U << start_bit); | |
| 106 | if (tmp != 0U) | |
| 107 | goto found; | |
| 108 | result += NBWORD; | |
| 109 | size -= NBWORD; | |
| 110 | } | |
| 111 | while (size) { | |
| 112 | if ((tmp = *p++) != 0U) | |
| 113 | goto found; | |
| 114 | result += NBWORD; | |
| 115 | size -= NBWORD; | |
| 116 | } | |
| 117 | return -1; | |
| 118 | found: | |
| 119 | return result + ffs(tmp) - 1; | |
| 120 | } |