split-out memalign and realloc

 -Erik

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;
+}
+