1 files changed, 127 insertions, 0 deletions
diff --git a/nuttx/mm/mm_heap/mm_extend.c b/nuttx/mm/mm_heap/mm_extend.c
new file mode 100644
index 000000000..d8a7f72f4
--- /dev/null
+++ b/nuttx/mm/mm_heap/mm_extend.c
@@ -0,0 +1,127 @@
+/****************************************************************************
+ * mm/mm_heap/mm_extend.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 NuttX 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 THE
+ * COPYRIGHT OWNER 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <assert.h>
+
+#include <nuttx/mm.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define MIN_EXTEND (2 * SIZEOF_MM_ALLOCNODE)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: mm_extend
+ *
+ * Description:
+ *   Extend a heap region by add a block of (virtually) contiguous memory
+ *   to the end of the heap.
+ *
+ ****************************************************************************/
+
+void mm_extend(FAR struct mm_heap_s *heap, FAR void *mem, size_t size,
+               int region)
+{
+  struct mm_allocnode_s *oldnode;
+  struct mm_allocnode_s *newnode;
+  uintptr_t blockstart;
+  uintptr_t blockend;
+
+  /* Make sure that we were passed valid parameters */
+
+  DEBUGASSERT(heap && mem);
+#if CONFIG_MM_REGIONS > 1
+  DEBUGASSERT(size >= MIN_EXTEND && (unsigned)region < heap->mm_nregions);
+#else
+  DEBUGASSERT(size >= MIN_EXTEND && (unsigned)region == 0);
+#endif
+
+  /* Make sure that the memory region are properly aligned */
+
+  blockstart = (uintptr_t)mem;
+  blockend   = blockstart + size;
+
+  DEBUGASSERT(MM_ALIGN_UP(blockstart) == blockstart);
+  DEBUGASSERT(MM_ALIGN_DOWN(blockend) == blockend);
+
+  /* Take the memory manager semaphore */
+
+  mm_takesemaphore(heap);
+
+  /* Get the terminal node in the old heap.  The block to extend must
+   * immediately follow this node.
+   */
+
+  oldnode = heap->mm_heapend[region];
+  DEBUGASSERT((uintptr_t)oldnode + SIZEOF_MM_ALLOCNODE == (uintptr_t)mem);
+
+  /* The size of the old node now extends to the new terminal node.
+   * This is the old size (SIZEOF_MM_ALLOCNODE) plus the size of
+   * the block (size) minus the size of the new terminal node
+   * (SIZEOF_MM_ALLOCNODE) or simply:
+   */
+
+  oldnode->size = size;
+
+  /* The old node should already be marked as allocated */
+
+  DEBUGASSERT((oldnode->preceding & MM_ALLOC_BIT) != 0);
+
+  /* Get and initialize the new terminal node in the heap */
+
+  newnode            = (FAR struct mm_allocnode_s *)(blockend - SIZEOF_MM_ALLOCNODE);
+  newnode->size      = SIZEOF_MM_ALLOCNODE;
+  newnode->preceding = oldnode->size | MM_ALLOC_BIT;
+
+  heap->mm_heapend[region] = newnode;
+  mm_givesemaphore(heap);
+
+  /* Finally "free" the new block of memory where the old terminal node was
+   * located.
+   */
+
+  mm_free(heap, (FAR void *)mem);
+}