uIP 1.0: lib/memb.c Source File

00001 /*
+00002  * Copyright (c) 2004, Swedish Institute of Computer Science.
+00003  * All rights reserved.
+00004  *
+00005  * Redistribution and use in source and binary forms, with or without
+00006  * modification, are permitted provided that the following conditions
+00007  * are met:
+00008  * 1. Redistributions of source code must retain the above copyright
+00009  *    notice, this list of conditions and the following disclaimer.
+00010  * 2. Redistributions in binary form must reproduce the above copyright
+00011  *    notice, this list of conditions and the following disclaimer in the
+00012  *    documentation and/or other materials provided with the distribution.
+00013  * 3. Neither the name of the Institute nor the names of its contributors
+00014  *    may be used to endorse or promote products derived from this software
+00015  *    without specific prior written permission.
+00016  *
+00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+00027  * SUCH DAMAGE.
+00028  *
+00029  * This file is part of the uIP TCP/IP stack
+00030  *
+00031  * Author: Adam Dunkels <adam@sics.se>
+00032  *
+00033  * $Id: memb.c,v 1.1 2006/06/12 08:21:43 adam Exp $
+00034  */
+00035 
+00036 /**
+00037  * \addtogroup memb
+00038  * @{
+00039  */
+00040 
+00041  /**
+00042  * \file
+00043  * Memory block allocation routines.
+00044  * \author Adam Dunkels <adam@sics.se>
+00045  */
+00046 #include <string.h>
+00047 
+00048 #include "memb.h"
+00049 
+00050 /*---------------------------------------------------------------------------*/
+00051 void
+00052 memb_init(struct memb_blocks *m)
+00053 {
+00054   memset(m->count, 0, m->num);
+00055   memset(m->mem, 0, m->size * m->num);
+00056 }
+00057 /*---------------------------------------------------------------------------*/
+00058 void *
+00059 memb_alloc(struct memb_blocks *m)
+00060 {
+00061   int i;
+00062 
+00063   for(i = 0; i < m->num; ++i) {
+00064     if(m->count[i] == 0) {
+00065       /* If this block was unused, we increase the reference count to
+00066          indicate that it now is used and return a pointer to the
+00067          memory block. */
+00068       ++(m->count[i]);
+00069       return (void *)((char *)m->mem + (i * m->size));
+00070     }
+00071   }
+00072 
+00073   /* No free block was found, so we return NULL to indicate failure to
+00074      allocate block. */
+00075   return NULL;
+00076 }
+00077 /*---------------------------------------------------------------------------*/
+00078 char
+00079 memb_free(struct memb_blocks *m, void *ptr)
+00080 {
+00081   int i;
+00082   char *ptr2;
+00083 
+00084   /* Walk through the list of blocks and try to find the block to
+00085      which the pointer "ptr" points to. */
+00086   ptr2 = (char *)m->mem;
+00087   for(i = 0; i < m->num; ++i) {
+00088     
+00089     if(ptr2 == (char *)ptr) {
+00090       /* We've found to block to which "ptr" points so we decrease the
+00091          reference count and return the new value of it. */
+00092       if(m->count[i] > 0) {
+00093         /* Make sure that we don't deallocate free memory. */
+00094         --(m->count[i]);
+00095       }
+00096       return m->count[i];
+00097     }
+00098     ptr2 += m->size;
+00099   }
+00100   return -1;
+00101 }
+00102 /*---------------------------------------------------------------------------*/
+00103 
+00104 /** @} */
+