basic memory pool implementation

include/btstack/memory_pool.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2011 by Matthias Ringwald
+ *
+ * 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 copyright holders nor the names of
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD 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 MATTHIAS
+ * RINGWALD 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.
+ *
+ */
+
+/*
+ *  memory_pool.h
+ *
+ *  @Brief Fixed-size block allocation
+ *
+ *  @Assumption block_size >= sizeof(void *)
+ *  @Assumption size of storage >= count * block_size
+ *
+ *  @Note minimal implementation, no error checking/handling
+ */
+
+#pragma once
+
+typedef void * memory_pool_t;
+
+// initialize memory pool with with given storage, block size and count
+void   memory_pool_create(memory_pool_t *pool, void * storage, int count, int block_size);
+
+// get free block from pool, @returns NULL or pointer to block
+void * memory_pool_get(memory_pool_t *pool);
+
+// return previously reserved block to memory pool
+void   memory_pool_free(memory_pool_t *pool, void * block);

src/Makefile.in

@@ -23,6 +23,7 @@ BTdaemon_SOURCES =  $(libBTstack_SOURCES) \
     $(usb_sources)          \
     l2cap.c                 \
     l2cap_signaling.c       \
+    memory_pool.c           \
     $(remote_device_db_sources)  \
     rfcomm.c                \
     sdp.c                   \

src/memory_pool.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2011 by Matthias Ringwald
+ *
+ * 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 copyright holders nor the names of
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD 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 MATTHIAS
+ * RINGWALD 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.
+ *
+ */
+
+/*
+ *  memory_pool.c
+ *
+ *  Fixed-size block allocation
+ *
+ *  Free blocks are kept in singly linked list
+ *
+ */
+
+#include <btstack/memory_pool.h>
+#include <stddef.h>
+
+typedef struct node {
+    struct node * next;
+} node_t;
+
+void memory_pool_create(memory_pool_t *pool, void * storage, int count, int block_size){
+    node_t *free_blocks = (node_t*) pool;
+    char   *mem_ptr = (char *) storage;
+    int i;
+    
+    // create singly linked list of all available blocks
+    free_blocks->next = NULL;
+    for (i = 0 ; i < count ; i++, mem_ptr += block_size){
+        node_t * node      = (node_t*) mem_ptr;
+        node->next         = free_blocks->next;
+        free_blocks->next  = node;
+    }
+}
+
+void * memory_pool_get(memory_pool_t *pool){
+    node_t *free_blocks = (node_t*) pool;
+    
+    if (!free_blocks) return NULL;
+    
+    // remove first
+    node_t *node      = free_blocks->next;
+    free_blocks->next = node->next;
+    
+    return (void*) node;
+}
+
+void memory_pool_free(memory_pool_t *pool, void * block){
+    node_t *free_blocks = (node_t*) pool;
+    node_t *node        = (node_t*) block;
+    // add block as node to list
+    node->next          = free_blocks->next;
+    free_blocks->next   = node;
+}