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/*
* Copyright (c) 2008, 2009, 2011 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "bitmap.h"
#include <string.h>
/* Allocates and returns a bitmap initialized to all-1-bits. */
unsigned long *
bitmap_allocate1(size_t n_bits)
{
size_t n_bytes = bitmap_n_bytes(n_bits);
size_t n_longs = bitmap_n_longs(n_bits);
unsigned long *bitmap;
/* Allocate and initialize most of the bitmap. */
bitmap = xmalloc(n_bytes);
memset(bitmap, 0xff, n_bytes);
/* Ensure that the last "unsigned long" in the bitmap only has as many
* 1-bits as there actually should be. */
bitmap[n_longs - 1] = (1UL << (n_bits % BITMAP_ULONG_BITS)) - 1;
return bitmap;
}
/* Sets 'count' consecutive bits in 'bitmap', starting at bit offset 'start',
* to 'value'. */
void
bitmap_set_multiple(unsigned long *bitmap, size_t start, size_t count,
bool value)
{
for (; count && start % BITMAP_ULONG_BITS; count--) {
bitmap_set(bitmap, start++, value);
}
for (; count >= BITMAP_ULONG_BITS; count -= BITMAP_ULONG_BITS) {
*bitmap_unit__(bitmap, start) = -(unsigned long) value;
start += BITMAP_ULONG_BITS;
}
for (; count; count--) {
bitmap_set(bitmap, start++, value);
}
}
/* Compares the 'n' bits in bitmaps 'a' and 'b'. Returns true if all bits are
* equal, false otherwise. */
bool
bitmap_equal(const unsigned long *a, const unsigned long *b, size_t n)
{
size_t i;
if (memcmp(a, b, n / BITMAP_ULONG_BITS * sizeof(unsigned long))) {
return false;
}
for (i = ROUND_DOWN(n, BITMAP_ULONG_BITS); i < n; i++) {
if (bitmap_is_set(a, i) != bitmap_is_set(b, i)) {
return false;
}
}
return true;
}
/* Scans 'bitmap' from bit offset 'start' to 'end', excluding 'end' itself.
* Returns the bit offset of the lowest-numbered bit set to 1, or 'end' if
* all of the bits are set to 0. */
size_t
bitmap_scan(const unsigned long int *bitmap, size_t start, size_t end)
{
/* XXX slow */
size_t i;
for (i = start; i < end; i++) {
if (bitmap_is_set(bitmap, i)) {
break;
}
}
return i;
}
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