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authorEric Andersen <andersen@codepoet.org>2002-09-05 05:54:26 +0000
committerEric Andersen <andersen@codepoet.org>2002-09-05 05:54:26 +0000
commitccf964b4c2b384d4e005a358f781e49cd6f89c68 (patch)
tree05c2b332ff646da2c0c7736f5551e0126d239874 /libc/stdlib/malloc-930716/realloc.c
parente72144d6265637d1e34bd79f5e373b4ff98d4d29 (diff)
split-out memalign and realloc
-Erik
Diffstat (limited to 'libc/stdlib/malloc-930716/realloc.c')
-rw-r--r--libc/stdlib/malloc-930716/realloc.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/libc/stdlib/malloc-930716/realloc.c b/libc/stdlib/malloc-930716/realloc.c
new file mode 100644
index 000000000..2b486ced5
--- /dev/null
+++ b/libc/stdlib/malloc-930716/realloc.c
@@ -0,0 +1,140 @@
+/* malloc.c - C standard library routine.
+ Copyright (c) 1989, 1993 Michael J. Haertel
+ You may redistribute this library under the terms of the
+ GNU Library General Public License (version 2 or any later
+ version) as published by the Free Software Foundation.
+ THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY EXPRESS OR IMPLIED
+ WARRANTY. IN PARTICULAR, THE AUTHOR MAKES NO REPRESENTATION OR
+ WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY OF THIS
+ SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. */
+
+#define _GNU_SOURCE
+#include <features.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "malloc.h"
+
+#ifdef __UCLIBC_HAS_THREADS__
+#include <pthread.h>
+extern pthread_mutex_t __malloclock;
+# define LOCK pthread_mutex_lock(&__malloclock)
+# define UNLOCK pthread_mutex_unlock(&__malloclock);
+#else
+# define LOCK
+# define UNLOCK
+#endif
+
+/* Resize the given region to the new size, returning a pointer
+ to the (possibly moved) region. This is optimized for speed;
+ some benchmarks seem to indicate that greater compactness is
+ achieved by unconditionally allocating and copying to a
+ new region. */
+void * realloc (void *ptr, size_t size)
+{
+ void *result, *previous;
+ size_t block, blocks, type;
+ size_t oldlimit;
+
+ if (!ptr)
+ return malloc(size);
+ if (!size) {
+ LOCK;
+ __free_unlocked(ptr);
+ result = __malloc_unlocked(0);
+ UNLOCK;
+ return(result);
+ }
+
+ LOCK;
+ block = BLOCK(ptr);
+
+ switch (type = _heapinfo[block].busy.type) {
+ case 0:
+ /* Maybe reallocate a large block to a small fragment. */
+ if (size <= BLOCKSIZE / 2) {
+ if ((result = __malloc_unlocked(size)) != NULL) {
+ memcpy(result, ptr, size);
+ __free_unlocked(ptr);
+ }
+ UNLOCK;
+ return result;
+ }
+
+ /* The new size is a large allocation as well; see if
+ we can hold it in place. */
+ blocks = BLOCKIFY(size);
+ if (blocks < _heapinfo[block].busy.info.size) {
+ /* The new size is smaller; return excess memory
+ to the free list. */
+ _heapinfo[block + blocks].busy.type = 0;
+ _heapinfo[block + blocks].busy.info.size
+ = _heapinfo[block].busy.info.size - blocks;
+ _heapinfo[block].busy.info.size = blocks;
+ __free_unlocked(ADDRESS(block + blocks));
+ UNLOCK;
+ return ptr;
+ } else if (blocks == _heapinfo[block].busy.info.size) {
+ /* No size change necessary. */
+ UNLOCK;
+ return ptr;
+ } else {
+ /* Won't fit, so allocate a new region that will. Free
+ the old region first in case there is sufficient adjacent
+ free space to grow without moving. */
+ blocks = _heapinfo[block].busy.info.size;
+ /* Prevent free from actually returning memory to the system. */
+ oldlimit = _heaplimit;
+ _heaplimit = 0;
+ __free_unlocked(ptr);
+ _heaplimit = oldlimit;
+ result = __malloc_unlocked(size);
+ if (!result) {
+ /* Now we're really in trouble. We have to unfree
+ the thing we just freed. Unfortunately it might
+ have been coalesced with its neighbors. */
+ if (_heapindex == block)
+ __malloc_unlocked(blocks * BLOCKSIZE);
+ else {
+ previous = __malloc_unlocked((block - _heapindex) * BLOCKSIZE);
+ __malloc_unlocked(blocks * BLOCKSIZE);
+ __free_unlocked(previous);
+ }
+ UNLOCK;
+ return NULL;
+ }
+ if (ptr != result)
+ memmove(result, ptr, blocks * BLOCKSIZE);
+ UNLOCK;
+ return result;
+ }
+ break;
+
+ default:
+ /* Old size is a fragment; type is logarithm to base two of
+ the fragment size. */
+ if ((size > 1 << (type - 1)) && (size <= 1 << type)) {
+ /* New size is the same kind of fragment. */
+ UNLOCK;
+ return ptr;
+ }
+ else {
+ /* New size is different; allocate a new space, and copy
+ the lesser of the new size and the old. */
+ result = __malloc_unlocked(size);
+ if (!result) {
+ UNLOCK;
+ return NULL;
+ }
+ memcpy(result, ptr, MIN(size, (size_t)(1 << type)));
+ __free_unlocked(ptr);
+ UNLOCK;
+ return result;
+ }
+ break;
+ }
+ UNLOCK;
+}
+