| /* |
| * Copyright (c) 2004, Swedish Institute of Computer Science. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of the Institute nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * This file is part of the Contiki operating system. |
| * |
| * Author: Adam Dunkels <adam@sics.se> |
| * |
| * $Id: memb.c,v 1.5 2004/09/12 20:24:55 adamdunkels Exp $ |
| */ |
| /** |
| * \defgroup memb Memory block management functions |
| * |
| * The memory block allocation routines provide a simple yet powerful |
| * set of functions for managing a set of memory blocks of fixed |
| * size. A set of memory blocks is statically declared with the |
| * MEMB() macro. Memory blocks are allocated from the declared |
| * memory by the memb_alloc() function, and are deallocated with the |
| * memb_free() function. |
| * |
| * \note Because of namespace clashes only one MEMB() can be |
| * declared per C module, and the name scope of a MEMB() memory |
| * block is local to each C module. |
| * |
| * The following example shows how to declare and use a memory block |
| * called "cmem" which has 8 chunks of memory with each memory chunk |
| * being 20 bytes large. |
| * |
| \code |
| #include "memb.h" |
| |
| MEMB(cmem, 20, 8); |
| |
| int main(int argc, char *argv[]) { |
| char *ptr; |
| |
| memb_init(&cmem); |
| |
| ptr = memb_alloc(&cmem); |
| |
| if(ptr != NULL) { |
| do_something(ptr); |
| } else { |
| printf("Could not allocate memory.\n"); |
| } |
| |
| if(memb_free(&cmem, ptr) == 0) { |
| printf("Deallocation succeeded.\n"); |
| } |
| } |
| \endcode |
| * |
| * @{ |
| */ |
| |
| /** |
| * \file |
| * Memory block allocation routines. |
| * \author Adam Dunkels <adam@sics.se> |
| */ |
| #include <string.h> |
| |
| #include "memb.h" |
| |
| /*------------------------------------------------------------------------------*/ |
| /** |
| * Initialize a memory block that was declared with MEMB(). |
| * |
| * \param m A memory block previosly declared with MEMB(). |
| */ |
| /*------------------------------------------------------------------------------*/ |
| void |
| memb_init(struct memb_blocks *m) |
| { |
| memset(m->mem, 0, (m->size + 1) * m->num); |
| } |
| /*------------------------------------------------------------------------------*/ |
| /** |
| * Allocate a memory block from a block of memory declared with MEMB(). |
| * |
| * \param m A memory block previosly declared with MEMB(). |
| */ |
| /*------------------------------------------------------------------------------*/ |
| char * |
| memb_alloc(struct memb_blocks *m) |
| { |
| int i; |
| char *ptr; |
| |
| ptr = m->mem; |
| for(i = 0; i < m->num; ++i) { |
| if(*ptr == 0) { |
| /* If this block was unused, we increase the reference count to |
| indicate that it now is used and return a pointer to the |
| first byte following the reference counter. */ |
| ++*ptr; |
| return ptr + 1; |
| } |
| ptr += m->size + 1; |
| } |
| |
| /* No free block was found, so we return NULL to indicate failure to |
| allocate block. */ |
| return NULL; |
| } |
| /*------------------------------------------------------------------------------*/ |
| /** |
| * Deallocate a memory block from a memory block previously declared |
| * with MEMB(). |
| * |
| * \param m m A memory block previosly declared with MEMB(). |
| * |
| * \param ptr A pointer to the memory block that is to be deallocated. |
| * |
| * \return The new reference count for the memory block (should be 0 |
| * if successfully deallocated) or -1 if the pointer "ptr" did not |
| * point to a legal memory block. |
| */ |
| /*------------------------------------------------------------------------------*/ |
| char |
| memb_free(struct memb_blocks *m, void *ptr) |
| { |
| int i; |
| char *ptr2; |
| |
| /* Walk through the list of blocks and try to find the block to |
| which the pointer "ptr" points to. */ |
| ptr2 = m->mem; |
| for(i = 0; i < m->num; ++i) { |
| |
| if(ptr2 == (char *)ptr - 1) { |
| /* We've found to block to which "ptr" points so we decrease the |
| reference count and return the new value of it. */ |
| return --*ptr2; |
| } |
| ptr2 += m->size + 1; |
| } |
| return -1; |
| } |
| /*------------------------------------------------------------------------------*/ |
| /** |
| * Increase the reference count for a memory chunk. |
| * |
| * \note No sanity checks are currently made. |
| * |
| * \param m m A memory block previosly declared with MEMB(). |
| * |
| * \param ptr A pointer to the memory chunk for which the reference |
| * count should be increased. |
| * |
| * \return The new reference count. |
| */ |
| /*------------------------------------------------------------------------------*/ |
| char |
| memb_ref(struct memb_blocks *m, char *ptr) |
| { |
| return ++*(ptr - 1); |
| } |
| /*------------------------------------------------------------------------------*/ |
| |
| /** @} */ |