--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/usr/src/lib/libc/port/gen/memalign.c	Tue Jun 14 00:00:00 2005 -0700
@@ -0,0 +1,183 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+/*	Copyright (c) 1988 AT&T	*/
+/*	  All Rights Reserved  	*/
+
+
+#pragma weak memalign = _memalign
+
+#include "synonyms.h"
+#include "mallint.h"
+#include "mtlib.h"
+
+#define	_misaligned(p)		((unsigned)(p) & 3)
+		/* 4-byte "word" alignment is considered ok in LP64 */
+#define	_nextblk(p, size)	((TREE *)((uintptr_t)(p) + (size)))
+
+/*
+ * memalign(align, nbytes)
+ *
+ * Description:
+ *	Returns a block of specified size on a specified alignment boundary.
+ *
+ * Algorithm:
+ *	Malloc enough to ensure that a block can be aligned correctly.
+ *	Find the alignment point and return the fragments
+ *	before and after the block.
+ *
+ * Errors:
+ *	Returns NULL and sets errno as follows:
+ *	[EINVAL]
+ *		if nbytes = 0,
+ *		or if alignment is misaligned,
+ *		or if the heap has been detectably corrupted.
+ *	[ENOMEM]
+ *		if the requested memory could not be allocated.
+ */
+
+void *
+memalign(size_t align, size_t nbytes)
+{
+	size_t	 reqsize;	/* Num of bytes to get from malloc() */
+	TREE	*p;		/* Ptr returned from malloc() */
+	TREE	*blk;		/* For addressing fragment blocks */
+	size_t	blksize;	/* Current (shrinking) block size */
+	TREE	*alignedp;	/* Ptr to properly aligned boundary */
+	TREE	*aligned_blk;	/* The block to be returned */
+	size_t	frag_size;	/* size of fragments fore and aft */
+	size_t	 x;
+
+	/*
+	 * check for valid size and alignment parameters
+	 * MAX_ALIGN check prevents overflow in later calculation.
+	 */
+	if (nbytes == 0 || _misaligned(align) || align == 0 ||
+	    align > MAX_ALIGN) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	/*
+	 * Malloc enough memory to guarantee that the result can be
+	 * aligned correctly. The worst case is when malloc returns
+	 * a block so close to the next alignment boundary that a
+	 * fragment of minimum size cannot be created.  In order to
+	 * make sure we can handle this, we need to force the
+	 * alignment to be at least as large as the minimum frag size
+	 * (MINSIZE + WORDSIZE).
+	 */
+
+	/* check for size that could overflow calculations */
+	if (nbytes > MAX_MALLOC) {
+		errno = ENOMEM;
+		return (NULL);
+	}
+	ROUND(nbytes);
+	if (nbytes < MINSIZE)
+		nbytes = MINSIZE;
+	ROUND(align);
+	while (align < MINSIZE + WORDSIZE)
+		align <<= 1;
+	reqsize = nbytes + align + (MINSIZE + WORDSIZE);
+
+	/* check for overflow */
+	if (reqsize < nbytes) {
+		errno = ENOMEM;
+		return (NULL);
+	}
+
+	p = (TREE *)malloc(reqsize);
+	if (p == (TREE *)NULL) {
+		/* malloc sets errno */
+		return (NULL);
+	}
+	lmutex_lock(&libc_malloc_lock);
+
+	/*
+	 * get size of the entire block (overhead and all)
+	 */
+	blk = BLOCK(p);			/* back up to get length word */
+	blksize = SIZE(blk);
+	CLRBITS01(blksize);
+
+	/*
+	 * locate the proper alignment boundary within the block.
+	 */
+	x = (size_t)p;
+	if (x % align != 0)
+		x += align - (x % align);
+	alignedp = (TREE *)x;
+	aligned_blk = BLOCK(alignedp);
+
+	/*
+	 * Check out the space to the left of the alignment
+	 * boundary, and split off a fragment if necessary.
+	 */
+	frag_size = (size_t)aligned_blk - (size_t)blk;
+	if (frag_size != 0) {
+		/*
+		 * Create a fragment to the left of the aligned block.
+		 */
+		if (frag_size < MINSIZE + WORDSIZE) {
+			/*
+			 * Not enough space. So make the split
+			 * at the other end of the alignment unit.
+			 * We know this yields enough space, because
+			 * we forced align >= MINSIZE + WORDSIZE above.
+			 */
+			frag_size += align;
+			aligned_blk = _nextblk(aligned_blk, align);
+		}
+		blksize -= frag_size;
+		SIZE(aligned_blk) = blksize | BIT0;
+		frag_size -= WORDSIZE;
+		SIZE(blk) = frag_size | BIT0 | ISBIT1(SIZE(blk));
+		_free_unlocked(DATA(blk));
+	}
+
+	/*
+	 * Is there a (sufficiently large) fragment to the
+	 * right of the aligned block?
+	 */
+	frag_size = blksize - nbytes;
+	if (frag_size >= MINSIZE + WORDSIZE) {
+		/*
+		 * split and free a fragment on the right
+		 */
+		blksize = SIZE(aligned_blk);
+		SIZE(aligned_blk) = nbytes;
+		blk = NEXT(aligned_blk);
+		SETOLD01(SIZE(aligned_blk), blksize);
+		frag_size -= WORDSIZE;
+		SIZE(blk) = frag_size | BIT0;
+		_free_unlocked(DATA(blk));
+	}
+	lmutex_unlock(&libc_malloc_lock);
+	return (DATA(aligned_blk));
+}