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git.proxmox.com Git - ovs.git/blob - lib/bitmap.c
2 * Copyright (c) 2008, 2009, 2011 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
21 /* Allocates and returns a bitmap initialized to all-1-bits. */
23 bitmap_allocate1(size_t n_bits
)
25 size_t n_bytes
= bitmap_n_bytes(n_bits
);
26 size_t n_longs
= bitmap_n_longs(n_bits
);
27 unsigned long *bitmap
;
29 /* Allocate and initialize most of the bitmap. */
30 bitmap
= xmalloc(n_bytes
);
31 memset(bitmap
, 0xff, n_bytes
);
33 /* Ensure that the last "unsigned long" in the bitmap only has as many
34 * 1-bits as there actually should be. */
35 bitmap
[n_longs
- 1] = (1UL << (n_bits
% BITMAP_ULONG_BITS
)) - 1;
40 /* Sets 'count' consecutive bits in 'bitmap', starting at bit offset 'start',
43 bitmap_set_multiple(unsigned long *bitmap
, size_t start
, size_t count
,
46 for (; count
&& start
% BITMAP_ULONG_BITS
; count
--) {
47 bitmap_set(bitmap
, start
++, value
);
49 for (; count
>= BITMAP_ULONG_BITS
; count
-= BITMAP_ULONG_BITS
) {
50 *bitmap_unit__(bitmap
, start
) = -(unsigned long) value
;
51 start
+= BITMAP_ULONG_BITS
;
53 for (; count
; count
--) {
54 bitmap_set(bitmap
, start
++, value
);
58 /* Compares the 'n' bits in bitmaps 'a' and 'b'. Returns true if all bits are
59 * equal, false otherwise. */
61 bitmap_equal(const unsigned long *a
, const unsigned long *b
, size_t n
)
65 if (memcmp(a
, b
, n
/ BITMAP_ULONG_BITS
* sizeof(unsigned long))) {
68 for (i
= ROUND_DOWN(n
, BITMAP_ULONG_BITS
); i
< n
; i
++) {
69 if (bitmap_is_set(a
, i
) != bitmap_is_set(b
, i
)) {
76 /* Scans 'bitmap' from bit offset 'start' to 'end', excluding 'end' itself.
77 * Returns the bit offset of the lowest-numbered bit set to 1, or 'end' if
78 * all of the bits are set to 0. */
80 bitmap_scan(const unsigned long int *bitmap
, size_t start
, size_t end
)
85 for (i
= start
; i
< end
; i
++) {
86 if (bitmap_is_set(bitmap
, i
)) {