Merge devel code into the trunk.

[tinyos-2.x.git] / tos / system / PoolP.nc

diff --git a/tos/system/PoolP.nc b/tos/system/PoolP.nc
new file mode 100644 (file)
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+++ b/tos/system/PoolP.nc
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+/* $Id$ */
+/*
+ * Copyright (c) 2006 Stanford University.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - 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.
+ * - Neither the name of the Stanford University 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 COPYRIGHT HOLDERS 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 STANFORD
+ * UNIVERSITY OR ITS 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.
+ */
+
+
+/**
+ *  Implementation of a general dynamic memory pool component.
+ *  Note that the allocation/deallocation policies are 
+ *  different than traditional dynamic allocators such as
+ *  malloc or slab allocators. When initialized, the Pool
+ *  contains <code>size</code> items of type <code>pool_t</code>.
+ *  These elements can be removed from the pool for use with 
+ *  <code>Pool.get</code>, and new elements can be placed in
+ *  the pool with <code>Pool.put</code>. The pool allows 
+ *  components to <code>put</code> elements besides those which
+ *  were obtained with <code>get</code>. The pool can never have
+ *  more than <code>size</code> elements in it.
+ *
+ *  @author Philip Levis
+ *  @author Kyle Jamieson
+ *  @date   $Date$
+ */
+
+generic module PoolP(typedef pool_t, uint8_t size) {
+  provides {
+    interface Init;
+    interface Pool<pool_t>;
+  }
+}
+implementation {
+  uint8_t free;
+  uint8_t index;
+  pool_t* queue[size];
+  pool_t pool[size];
+
+  command error_t Init.init() {
+    int i;
+    for (i = 0; i < size; i++) {
+      queue[i] = &pool[i];
+    }
+    free = size;
+    index = 0;
+    return SUCCESS;
+  }
+  
+  command bool Pool.empty() {
+    return free == 0;
+  }
+  command uint8_t Pool.size() {
+    return free;
+  }
+    
+  command uint8_t Pool.maxSize() {
+    return size;
+  }
+
+  command pool_t* Pool.get() {
+    if (free) {
+      pool_t* rval = queue[index];
+      queue[index] = NULL;
+      free--;
+      index = (index + 1) % size;
+      return rval;
+    }
+    return NULL;
+  }
+
+  command error_t Pool.put(pool_t* newVal) {
+    if (free >= size) {
+      return FAIL;
+    }
+    else {
+      uint8_t emptyIndex = (index + free) % size;
+      queue[emptyIndex] = newVal;
+      free++;
+      return SUCCESS;
+    }
+  }
+}