mirror of git://git.sysmocom.de/ofono
165 lines
3.2 KiB
C
165 lines
3.2 KiB
C
/*
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*
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* oFono - Open Source Telephony
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*
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* Copyright (C) 2008-2010 Intel Corporation. All rights reserved.
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#define _GNU_SOURCE
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#include <string.h>
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#include <glib.h>
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#include "idmap.h"
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#define BITS_PER_LONG (sizeof(unsigned long) * 8)
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struct idmap {
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unsigned long *bits;
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unsigned int size;
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};
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static inline int ffz(unsigned long word)
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{
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return __builtin_ctzl(~word);
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}
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/*
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* Stolen from linux kernel lib/find_next_bit.c
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*/
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static unsigned int find_next_zero_bit(const unsigned long *addr,
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unsigned int size,
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unsigned int offset)
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{
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const unsigned long *p = addr + offset / BITS_PER_LONG;
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unsigned int result = offset & ~(BITS_PER_LONG-1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (BITS_PER_LONG - offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if (~(tmp = *(p++)))
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp |= ~0UL << size;
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. */
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found_middle:
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return result + ffz(tmp);
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}
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struct idmap *idmap_new(unsigned int size)
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{
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struct idmap *ret = g_new0(struct idmap, 1);
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ret->bits = g_new0(unsigned long,
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(size + BITS_PER_LONG - 1) / BITS_PER_LONG);
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ret->size = size;
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return ret;
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}
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void idmap_free(struct idmap *idmap)
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{
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g_free(idmap->bits);
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g_free(idmap);
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}
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void idmap_put(struct idmap *idmap, unsigned int bit)
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{
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unsigned int offset = (bit - 1) / BITS_PER_LONG;
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bit -= 1;
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if (bit > idmap->size)
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return;
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bit %= BITS_PER_LONG;
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idmap->bits[offset] &= ~(1 << bit);
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}
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unsigned int idmap_alloc(struct idmap *idmap)
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{
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unsigned int bit;
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unsigned int offset;
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bit = find_next_zero_bit(idmap->bits, idmap->size, 0);
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if (bit >= idmap->size)
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return 0;
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offset = bit / BITS_PER_LONG;
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idmap->bits[offset] |= 1 << (bit % BITS_PER_LONG);
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return bit + 1;
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}
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/*
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* Allocate the next bit skipping the first last bits
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*/
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unsigned int idmap_alloc_next(struct idmap *idmap, unsigned int last)
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{
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unsigned int bit;
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unsigned int offset;
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bit = find_next_zero_bit(idmap->bits, idmap->size, last);
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if (bit >= idmap->size)
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return idmap_alloc(idmap);
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offset = bit / BITS_PER_LONG;
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idmap->bits[offset] |= 1 << (bit % BITS_PER_LONG);
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return bit + 1;
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}
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