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authorEric Andersen <andersen@codepoet.org>2002-07-18 15:00:07 +0000
committerEric Andersen <andersen@codepoet.org>2002-07-18 15:00:07 +0000
commit35d29fcb08fadaf006561a058746b0fce76a6a74 (patch)
treeb42a59394f8ee7dc7c11f71ae2d45b1e1beb834b /libc/stdlib/malloc/heap_free.c
parent3b1e82407a02aed6319c6686c5b06c2051a20cca (diff)
Miles Bader implemented a new mmap based malloc which is much
smarter than the old "malloc-simple", and actually works, unlike the old "malloc". So kill the old "malloc-simple" and the old "malloc" and replace them with Miles' new malloc implementation. Update Config files to match. Thanks Miles!
Diffstat (limited to 'libc/stdlib/malloc/heap_free.c')
-rw-r--r--libc/stdlib/malloc/heap_free.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/libc/stdlib/malloc/heap_free.c b/libc/stdlib/malloc/heap_free.c
new file mode 100644
index 000000000..20ef65572
--- /dev/null
+++ b/libc/stdlib/malloc/heap_free.c
@@ -0,0 +1,127 @@
+/*
+ * libc/stdlib/malloc-zarg/heap_free.c -- return memory to a heap
+ *
+ * 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"
+
+
+/* Return the memory area MEM of size SIZE to HEAP. */
+void
+__heap_free (struct heap *heap, void *mem, size_t size)
+{
+ struct heap_free_area *prev_fa, *fa, *new_fa;
+ void *end = (char *)mem + size;
+
+ mutex_lock (heap->lock);
+
+ HEAP_DEBUG (heap, "before __heap_free");
+
+ /* Find an adjacent free-list entry. */
+ for (prev_fa = 0, fa = heap->free_areas; fa; prev_fa = fa, fa = fa->next)
+ {
+ size_t fa_size = fa->size;
+ void *fa_end = HEAP_FREE_AREA_END (fa);
+ void *fa_mem = HEAP_FREE_AREA_START (fa);
+
+ if (fa_mem == end)
+ /* FA is just after MEM, grow down to encompass it. */
+ {
+ fa_size += size;
+
+ /* See if FA can now be merged with its predecessor. */
+ if (prev_fa && fa_mem - size == HEAP_FREE_AREA_END (prev_fa))
+ /* Yup; merge PREV_FA's info into FA. */
+ {
+ struct heap_free_area *pp = prev_fa->prev;
+ fa_size += prev_fa->size;
+ if (pp)
+ pp->next = fa;
+ else
+ heap->free_areas = fa;
+ fa->prev = pp;
+ }
+
+ fa->size = fa_size;
+
+ goto done;
+ }
+ else if (fa_end == mem)
+ /* FA is just before MEM, expand to encompass it. */
+ {
+ struct heap_free_area *next_fa = fa->next;
+
+ fa_size += size;
+
+ /* See if FA can now be merged with its successor. */
+ if (next_fa && fa_end + size == HEAP_FREE_AREA_START (next_fa))
+ {
+ /* Yup; merge FA's info into NEXT_FA. */
+ fa_size += next_fa->size;
+ if (prev_fa)
+ prev_fa->next = next_fa;
+ else
+ heap->free_areas = next_fa;
+ next_fa->prev = prev_fa;
+ fa = next_fa;
+ }
+ else
+ /* FA can't be merged; move the descriptor for it to the tail-end
+ of the memory block. */
+ {
+ 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;
+ fa = new_fa;
+ }
+
+ fa->size = fa_size;
+
+ goto done;
+ }
+ else if (fa_mem > mem)
+ /* We've reached the right spot in the free-list without finding an
+ adjacent free-area, so add a new free area to hold MEM. */
+ break;
+ }
+
+ /* Make a new free-list entry. */
+
+ /* NEW_FA initially holds only MEM. */
+ new_fa = (struct heap_free_area *)
+ ((char *)mem + size - sizeof (struct heap_free_area));
+ new_fa->size = size;
+ new_fa->next = fa;
+ new_fa->prev = prev_fa;
+
+ /* Insert NEW_FA in the free-list between PREV_FA and FA. */
+ if (prev_fa)
+ prev_fa->next = new_fa;
+ else
+ heap->free_areas = new_fa;
+ if (fa)
+ fa->prev = new_fa;
+
+ done:
+ HEAP_DEBUG (heap, "after __heap_free");
+
+ mutex_unlock (heap->lock);
+}