author | raf |
Tue, 13 Jun 2006 10:19:16 -0700 | |
changeset 2186 | 7b18ba5d9cfe |
parent 0 | 68f95e015346 |
child 2658 | bd713408aa10 |
permissions | -rw-r--r-- |
0 | 1 |
/* |
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* CDDL HEADER START |
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* |
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* The contents of this file are subject to the terms of the |
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* Common Development and Distribution License (the "License"). |
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* You may not use this file except in compliance with the License. |
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* |
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE |
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* or http://www.opensolaris.org/os/licensing. |
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* See the License for the specific language governing permissions |
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* and limitations under the License. |
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* |
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* When distributing Covered Code, include this CDDL HEADER in each |
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE. |
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* If applicable, add the following below this CDDL HEADER, with the |
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* fields enclosed by brackets "[]" replaced with your own identifying |
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* information: Portions Copyright [yyyy] [name of copyright owner] |
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* |
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* CDDL HEADER END |
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*/ |
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/* |
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* Copyright 2006 Sun Microsystems, Inc. All rights reserved. |
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* Use is subject to license terms. |
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*/ |
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||
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#pragma ident "%Z%%M% %I% %E% SMI" |
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/* Copyright (c) 1988 AT&T */ |
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/* All Rights Reserved */ |
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#pragma weak memalign = _memalign |
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#include "synonyms.h" |
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#include "mallint.h" |
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#include "mtlib.h" |
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#define _misaligned(p) ((unsigned)(p) & 3) |
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/* 4-byte "word" alignment is considered ok in LP64 */ |
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#define _nextblk(p, size) ((TREE *)((uintptr_t)(p) + (size))) |
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/* |
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* memalign(align, nbytes) |
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* |
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* Description: |
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* Returns a block of specified size on a specified alignment boundary. |
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* |
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* Algorithm: |
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* Malloc enough to ensure that a block can be aligned correctly. |
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* Find the alignment point and return the fragments |
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* before and after the block. |
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* |
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* Errors: |
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* Returns NULL and sets errno as follows: |
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* [EINVAL] |
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* if nbytes = 0, |
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* or if alignment is misaligned, |
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* or if the heap has been detectably corrupted. |
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* [ENOMEM] |
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* if the requested memory could not be allocated. |
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*/ |
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void * |
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memalign(size_t align, size_t nbytes) |
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{ |
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size_t reqsize; /* Num of bytes to get from malloc() */ |
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TREE *p; /* Ptr returned from malloc() */ |
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TREE *blk; /* For addressing fragment blocks */ |
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size_t blksize; /* Current (shrinking) block size */ |
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TREE *alignedp; /* Ptr to properly aligned boundary */ |
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TREE *aligned_blk; /* The block to be returned */ |
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size_t frag_size; /* size of fragments fore and aft */ |
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size_t x; |
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/* |
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* check for valid size and alignment parameters |
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* MAX_ALIGN check prevents overflow in later calculation. |
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*/ |
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if (nbytes == 0 || _misaligned(align) || align == 0 || |
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align > MAX_ALIGN) { |
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errno = EINVAL; |
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return (NULL); |
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} |
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/* |
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* Malloc enough memory to guarantee that the result can be |
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* aligned correctly. The worst case is when malloc returns |
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* a block so close to the next alignment boundary that a |
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* fragment of minimum size cannot be created. In order to |
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* make sure we can handle this, we need to force the |
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* alignment to be at least as large as the minimum frag size |
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* (MINSIZE + WORDSIZE). |
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*/ |
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/* check for size that could overflow calculations */ |
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if (nbytes > MAX_MALLOC) { |
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errno = ENOMEM; |
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return (NULL); |
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} |
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ROUND(nbytes); |
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if (nbytes < MINSIZE) |
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nbytes = MINSIZE; |
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ROUND(align); |
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while (align < MINSIZE + WORDSIZE) |
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align <<= 1; |
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reqsize = nbytes + align + (MINSIZE + WORDSIZE); |
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/* check for overflow */ |
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if (reqsize < nbytes) { |
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errno = ENOMEM; |
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return (NULL); |
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} |
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p = (TREE *)malloc(reqsize); |
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if (p == (TREE *)NULL) { |
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/* malloc sets errno */ |
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return (NULL); |
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} |
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(void) _private_mutex_lock(&libc_malloc_lock); |
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/* |
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* get size of the entire block (overhead and all) |
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*/ |
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blk = BLOCK(p); /* back up to get length word */ |
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blksize = SIZE(blk); |
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CLRBITS01(blksize); |
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/* |
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* locate the proper alignment boundary within the block. |
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*/ |
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x = (size_t)p; |
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if (x % align != 0) |
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x += align - (x % align); |
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alignedp = (TREE *)x; |
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aligned_blk = BLOCK(alignedp); |
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/* |
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* Check out the space to the left of the alignment |
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* boundary, and split off a fragment if necessary. |
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*/ |
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frag_size = (size_t)aligned_blk - (size_t)blk; |
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if (frag_size != 0) { |
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/* |
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* Create a fragment to the left of the aligned block. |
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*/ |
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if (frag_size < MINSIZE + WORDSIZE) { |
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/* |
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* Not enough space. So make the split |
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* at the other end of the alignment unit. |
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* We know this yields enough space, because |
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* we forced align >= MINSIZE + WORDSIZE above. |
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*/ |
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frag_size += align; |
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aligned_blk = _nextblk(aligned_blk, align); |
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} |
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blksize -= frag_size; |
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SIZE(aligned_blk) = blksize | BIT0; |
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frag_size -= WORDSIZE; |
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SIZE(blk) = frag_size | BIT0 | ISBIT1(SIZE(blk)); |
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_free_unlocked(DATA(blk)); |
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} |
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/* |
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* Is there a (sufficiently large) fragment to the |
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* right of the aligned block? |
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*/ |
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frag_size = blksize - nbytes; |
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if (frag_size >= MINSIZE + WORDSIZE) { |
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/* |
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* split and free a fragment on the right |
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*/ |
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blksize = SIZE(aligned_blk); |
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SIZE(aligned_blk) = nbytes; |
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blk = NEXT(aligned_blk); |
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SETOLD01(SIZE(aligned_blk), blksize); |
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frag_size -= WORDSIZE; |
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SIZE(blk) = frag_size | BIT0; |
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_free_unlocked(DATA(blk)); |
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} |
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(void) _private_mutex_unlock(&libc_malloc_lock); |
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return (DATA(aligned_blk)); |
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} |