1 /*
2 * Copyright (c) 2004, Swedish Institute of Computer Science.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the Institute nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * This file is part of the uIP TCP/IP stack
30 *
31 * Author: Adam Dunkels <[email protected]>
32 *
33 * $Id: memb.c,v 1.1 2006/06/12 08:21:43 adam Exp $
34 */
35
36 /**
37 * \addtogroup memb
38 * @{
39 */
40
41 /**
42 * \file
43 * Memory block allocation routines.
44 * \author Adam Dunkels <[email protected]>
45 */
46 #include <string.h>
47
48 #include "memb.h"
49
50 /*---------------------------------------------------------------------------*/
51 void
memb_init(struct memb_blocks * m)52 memb_init(struct memb_blocks *m)
53 {
54 memset(m->count, 0, m->num);
55 memset(m->mem, 0, m->size * m->num);
56 }
57 /*---------------------------------------------------------------------------*/
58 void *
memb_alloc(struct memb_blocks * m)59 memb_alloc(struct memb_blocks *m)
60 {
61 int i;
62
63 for(i = 0; i < m->num; ++i) {
64 if(m->count[i] == 0) {
65 /* If this block was unused, we increase the reference count to
66 indicate that it now is used and return a pointer to the
67 memory block. */
68 ++(m->count[i]);
69 return (void *)((char *)m->mem + (i * m->size));
70 }
71 }
72
73 /* No free block was found, so we return NULL to indicate failure to
74 allocate block. */
75 return NULL;
76 }
77 /*---------------------------------------------------------------------------*/
78 char
memb_free(struct memb_blocks * m,void * ptr)79 memb_free(struct memb_blocks *m, void *ptr)
80 {
81 int i;
82 char *ptr2;
83
84 /* Walk through the list of blocks and try to find the block to
85 which the pointer "ptr" points to. */
86 ptr2 = (char *)m->mem;
87 for(i = 0; i < m->num; ++i) {
88
89 if(ptr2 == (char *)ptr) {
90 /* We've found to block to which "ptr" points so we decrease the
91 reference count and return the new value of it. */
92 if(m->count[i] > 0) {
93 /* Make sure that we don't deallocate free memory. */
94 --(m->count[i]);
95 }
96 return m->count[i];
97 }
98 ptr2 += m->size;
99 }
100 return -1;
101 }
102 /*---------------------------------------------------------------------------*/
103
104 /** @} */
105