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/*
*
* oFono - Open Source Telephony
*
* Copyright (C) 2008-2011 Intel Corporation. All rights reserved.
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#define _GNU_SOURCE
#include <string.h>
#include <glib.h>
#include "idmap.h"
#define BITS_PER_LONG (sizeof(unsigned long) * 8)
struct idmap {
unsigned long *bits;
unsigned int size;
unsigned int min;
unsigned int max;
};
static inline int ffz(unsigned long word)
{
return __builtin_ctzl(~word);
}
/*
* Stolen from linux kernel lib/find_next_bit.c
*/
static unsigned int find_next_zero_bit(const unsigned long *addr,
unsigned int size,
unsigned int offset)
{
const unsigned long *p = addr + offset / BITS_PER_LONG;
unsigned int result = offset & ~(BITS_PER_LONG-1);
unsigned long tmp;
if (offset >= size)
return size;
size -= result;
offset %= BITS_PER_LONG;
if (offset) {
tmp = *(p++);
tmp |= ~0UL >> (BITS_PER_LONG - offset);
if (size < BITS_PER_LONG)
goto found_first;
if (~tmp)
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
while (size & ~(BITS_PER_LONG-1)) {
if (~(tmp = *(p++)))
goto found_middle;
size -= BITS_PER_LONG;
result += BITS_PER_LONG;
}
if (!size)
return result;
tmp = *p;
found_first:
tmp |= ~0UL << size;
if (tmp == ~0UL) /* Are any bits zero? */
return result + size; /* Nope. */
found_middle:
return result + ffz(tmp);
}
struct idmap *idmap_new_from_range(unsigned int min, unsigned int max)
{
struct idmap *ret = g_new0(struct idmap, 1);
unsigned int size = max - min + 1;
ret->bits = g_new0(unsigned long,
(size + BITS_PER_LONG - 1) / BITS_PER_LONG);
ret->size = size;
ret->min = min;
ret->max = max;
return ret;
}
struct idmap *idmap_new(unsigned int size)
{
return idmap_new_from_range(1, size);
}
void idmap_free(struct idmap *idmap)
{
g_free(idmap->bits);
g_free(idmap);
}
void idmap_put(struct idmap *idmap, unsigned int id)
{
unsigned int offset = (id - idmap->min) / BITS_PER_LONG;
id -= idmap->min;
if (id > idmap->size)
return;
id %= BITS_PER_LONG;
idmap->bits[offset] &= ~(1UL << id);
}
unsigned int idmap_alloc(struct idmap *idmap)
{
unsigned int bit;
unsigned int offset;
bit = find_next_zero_bit(idmap->bits, idmap->size, 0);
if (bit >= idmap->size)
return idmap->max + 1;
offset = bit / BITS_PER_LONG;
idmap->bits[offset] |= 1UL << (bit % BITS_PER_LONG);
return bit + idmap->min;
}
void idmap_take(struct idmap *idmap, unsigned int id)
{
unsigned int bit = id - idmap->min;
unsigned int offset;
if (bit >= idmap->size)
return;
offset = bit / BITS_PER_LONG;
idmap->bits[offset] |= 1UL << (bit % BITS_PER_LONG);
}
/*
* Allocate the next bit skipping the ids up to and including last. If there
* is no free ids until the max id is encountered, the counter is wrapped back
* to min and the search starts again.
*/
unsigned int idmap_alloc_next(struct idmap *idmap, unsigned int last)
{
unsigned int bit;
unsigned int offset;
if (last < idmap->min || last > idmap->max)
return idmap->max + 1;
bit = find_next_zero_bit(idmap->bits, idmap->size,
last - idmap->min + 1);
if (bit >= idmap->size)
return idmap_alloc(idmap);
offset = bit / BITS_PER_LONG;
idmap->bits[offset] |= 1UL << (bit % BITS_PER_LONG);
return bit + idmap->min;
}
unsigned int idmap_get_min(struct idmap *idmap)
{
return idmap->min;
}
unsigned int idmap_get_max(struct idmap *idmap)
{
return idmap->max;
}
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