1 /* $NetBSD: mem2.c,v 1.6 2002/01/21 19:49:52 tv Exp $ */
4 * Copyright (c) 1994, 1995 Jochen Pohl
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by Jochen Pohl for
19 * 4. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 #include <sys/cdefs.h>
35 #if defined(__RCSID) && !defined(lint)
36 __RCSID("$NetBSD: mem2.c,v 1.6 2002/01/21 19:49:52 tv Exp $");
38 __FBSDID("$FreeBSD$");
40 #include <sys/param.h>
41 #include <sys/types.h>
49 /* length of new allocated memory blocks */
50 static size_t mblklen;
52 /* offset of next free byte in mbuf */
53 static size_t nxtfree;
55 /* current buffer to server memory requests from */
64 mblklen = ((MBLKSIZ + pgsz - 1) / pgsz) * pgsz;
70 * Allocate memory in large chunks to avoid space and time overhead of
71 * malloc(). This is possible because memory allocated by xalloc()
72 * need never to be freed.
80 /* Align to at least 8 bytes. */
82 if (nxtfree + sz > mblklen) {
83 /* use mmap() instead of malloc() to avoid malloc overhead. */
84 prot = PROT_READ | PROT_WRITE;
85 flags = MAP_ANON | MAP_PRIVATE;
86 mbuf = mmap(NULL, mblklen, prot, flags, -1, (off_t)0);
87 if (mbuf == (void *)MAP_FAILED)
88 err(1, "can't map memory");
89 (void)memset(mbuf, 0, mblklen);
93 ptr = (char *)mbuf + nxtfree;