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/*
Unix SMB/CIFS implementation.
simple bitmap functions
Copyright (C) Andrew Tridgell 1992-1998
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "lib/util/bitmap.h"
struct bitmap {
unsigned int n;
uint32_t b[1]; /* We allocate more */
};
/* these functions provide a simple way to allocate integers from a
pool without repetition */
/****************************************************************************
talloc a bitmap
****************************************************************************/
struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
{
struct bitmap *bm;
bm = (struct bitmap *)talloc_zero_size(
mem_ctx,
offsetof(struct bitmap, b) + sizeof(uint32_t)*((n+31)/32));
if (!bm) return NULL;
talloc_set_name_const(bm, "struct bitmap");
bm->n = n;
return bm;
}
/****************************************************************************
copy as much of the source bitmap as will fit in the destination bitmap.
****************************************************************************/
int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
{
int count = MIN(dst->n, src->n);
SMB_ASSERT(dst->b != src->b);
memcpy(dst->b, src->b, sizeof(uint32_t)*((count+31)/32));
return count;
}
/****************************************************************************
set a bit in a bitmap
****************************************************************************/
bool bitmap_set(struct bitmap *bm, unsigned i)
{
if (i >= bm->n) {
DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
i, bm->n));
return false;
}
bm->b[i/32] |= (1<<(i%32));
return true;
}
/****************************************************************************
clear a bit in a bitmap
****************************************************************************/
bool bitmap_clear(struct bitmap *bm, unsigned i)
{
if (i >= bm->n) {
DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
i, bm->n));
return false;
}
bm->b[i/32] &= ~(1<<(i%32));
return true;
}
/****************************************************************************
query a bit in a bitmap
****************************************************************************/
bool bitmap_query(struct bitmap *bm, unsigned i)
{
if (i >= bm->n) return false;
if (bm->b[i/32] & (1<<(i%32))) {
return true;
}
return false;
}
/****************************************************************************
find a zero bit in a bitmap starting at the specified offset, with
wraparound
****************************************************************************/
int bitmap_find(struct bitmap *bm, unsigned ofs)
{
unsigned int i, j;
if (ofs > bm->n) ofs = 0;
i = ofs;
while (i < bm->n) {
if (~(bm->b[i/32])) {
j = i;
do {
if (!bitmap_query(bm, j)) return j;
j++;
} while (j & 31 && j < bm->n);
}
i += 32;
i &= ~31;
}
i = 0;
while (i < ofs) {
if (~(bm->b[i/32])) {
j = i;
do {
if (!bitmap_query(bm, j)) return j;
j++;
} while (j & 31 && j < bm->n);
}
i += 32;
i &= ~31;
}
return -1;
}
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