Import of the contiki-2.x development code from the SICS internal CVS server

core/lib/mmem.c

@@ -0,0 +1,156 @@
+/*
+ * 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.
+ *
+ * @(#)$Id: mmem.c,v 1.1 2006/06/17 22:41:18 adamdunkels Exp $
+ */
+
+/**
+ * \addtogroup mmem
+ * @{
+ */
+
+/**
+ * \file
+ *         Implementation of the managed memory allocator
+ * \author
+ *         Adam Dunkels <adam@sics.se>
+ * 
+ */
+
+
+#include "mmem.h"
+#include "list.h"
+
+#include <string.h>
+
+#define MMEM_SIZE 4096
+
+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;
+}
+/*---------------------------------------------------------------------------*/
+
+/** @} */