/* * Copyright (c) 2005, 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. * */ /** * \addtogroup mmem * @{ */ /** * \file * Implementation of the managed memory allocator * \author * Adam Dunkels <adam@sics.se> * */ #include "mmem.h" #include "list.h" #include "contiki-conf.h" #include <string.h> #ifdef MMEM_CONF_SIZE #define MMEM_SIZE MMEM_CONF_SIZE #else #define MMEM_SIZE 4096 #endif LIST(mmemlist); unsigned int avail_memory; static char memory[MMEM_SIZE]; /*---------------------------------------------------------------------------*/ /** * \brief Allocate a managed memory block * \param m A pointer to a struct mmem. * \param size The size of the requested memory block * \return Non-zero if the memory could be allocated, zero if memory * was not available. * \author Adam Dunkels * * This function allocates a chunk of managed memory. The * memory allocated with this function must be deallocated * using the mmem_free() function. * * \note This function does NOT return a pointer to the * allocated memory, but a pointer to a structure that * contains information about the managed memory. The * macro MMEM_PTR() is used to get a pointer to the * allocated memory. * */ int mmem_alloc(struct mmem *m, unsigned int size) { /* Check if we have enough memory left for this allocation. */ if(avail_memory < size) { return 0; } /* We had enough memory so we add this memory block to the end of the list of allocated memory blocks. */ list_add(mmemlist, m); /* Set up the pointer so that it points to the first available byte in the memory block. */ m->ptr = &memory[MMEM_SIZE - avail_memory]; /* Remember the size of this memory block. */ m->size = size; /* Decrease the amount of available memory. */ avail_memory -= size; /* Return non-zero to indicate that we were able to allocate memory. */ return 1; } /*---------------------------------------------------------------------------*/ /** * \brief Deallocate a managed memory block * \param m A pointer to the managed memory block * \author Adam Dunkels * * This function deallocates a managed memory block that * previously has been allocated with mmem_alloc(). * */ void mmem_free(struct mmem *m) { struct mmem *n; if(m->next != NULL) { /* Compact the memory after the allocation that is to be removed by moving it downwards. */ memmove(m->ptr, m->next->ptr, &memory[MMEM_SIZE - avail_memory] - (char *)m->next->ptr); /* Update all the memory pointers that points to memory that is after the allocation that is to be removed. */ for(n = m->next; n != NULL; n = n->next) { n->ptr = (void *)((char *)n->ptr - m->size); } } avail_memory += m->size; /* Remove the memory block from the list. */ list_remove(mmemlist, m); } /*---------------------------------------------------------------------------*/ /** * \brief Initialize the managed memory module * \author Adam Dunkels * * This function initializes the managed memory module and * should be called before any other function from the * module. * */ void mmem_init(void) { list_init(mmemlist); avail_memory = MMEM_SIZE; } /*---------------------------------------------------------------------------*/ /** @} */