1 files changed, 71 insertions, 0 deletions
diff --git a/libc/stdlib/malloc/heap_append_free.c b/libc/stdlib/malloc/heap_append_free.c
new file mode 100644
index 000000000..42f0cf5bb
--- /dev/null
+++ b/libc/stdlib/malloc/heap_append_free.c
@@ -0,0 +1,71 @@
+/*
+ * libc/stdlib/malloc-zarg/heap_append_free.c -- append to heap free area
+ *
+ *  Copyright (C) 2002  NEC Corporation
+ *  Copyright (C) 2002  Miles Bader <miles@gnu.org>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License.  See the file COPYING.LIB in the main
+ * directory of this archive for more details.
+ * 
+ * Written by Miles Bader <miles@gnu.org>
+ */
+
+#include <stdlib.h>
+
+#include "heap.h"
+
+
+/* If the block MEM, of size SIZE, immediately follows an existing free-area
+   in HEAP, use it to extend that free-area, and return true; otherwise return
+   false.  */
+int
+__heap_append_free (struct heap *heap, void *mem, size_t size)
+{
+  int success = 0;
+  struct heap_free_area *fa;
+
+  mutex_lock (heap->lock);
+
+  HEAP_DEBUG (heap, "before __heap_append_free");
+
+  /* Find an adjacent free-list entry.  */
+  for (fa = heap->free_areas; fa; fa = fa->next)
+    if (HEAP_FREE_AREA_END (fa) == mem)
+      /* MEM follows FA, extend FA to include it.  Since the descriptor for FA
+	 is located at the end, we must actually write a new descriptor.  Note
+	 that we _don't_ handle the case where the extended FA can be merged
+	 with a following free area; this is because this function is
+	 generally only used in cases were we believe that usually won't
+	 happen (it doesn't cause any incorrectness, and the two blocks can be
+	 merged by __heap_free later).  */
+      {
+	struct heap_free_area *next_fa = fa->next;
+	struct heap_free_area *prev_fa = fa->prev;
+	size_t fa_size = fa->size;
+	struct heap_free_area *new_fa =
+	  (struct heap_free_area *)((char *)fa + size);
+
+	/* Update surrounding free-areas to point to FA's new address.  */
+	if (prev_fa)
+	  prev_fa->next = new_fa;
+	else
+	  heap->free_areas = new_fa;
+	if (next_fa)
+	  next_fa->prev = new_fa;
+
+	/* Fill in the moved descriptor.  */
+	new_fa->prev = prev_fa;
+	new_fa->next = next_fa;
+	new_fa->size = fa_size + size;
+
+	success = 1;
+	break;
+      }
+
+  HEAP_DEBUG (heap, "after __heap_append_free");
+
+  mutex_unlock (heap->lock);
+
+  return success;
+}