1 /* $NetBSD: diskbuf.c,v 1.7 2017/01/24 11:09:14 nonaka Exp $ */
2
3 /*
4 * Copyright (c) 1996
5 * Matthias Drochner. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29 /* data buffer for BIOS disk / DOS I/O */
30
31 #include <sys/inttypes.h>
32
33 #include <lib/libsa/stand.h>
34 #include "diskbuf.h"
35
36 char *diskbufp; /* allocated from heap */
37
38 const void *diskbuf_user;
39
40 /*
41 * Global shared "diskbuf" is used as read ahead buffer.
42 * This MAY have to not cross a 64k boundary.
43 * In practise it is allocated out of the heap early on...
44 * NB a statically allocated diskbuf is not guaranteed to not
45 * cross a 64k boundary.
46 */
47 char *
alloc_diskbuf(const void * user)48 alloc_diskbuf(const void *user)
49 {
50 diskbuf_user = user;
51 if (!diskbufp) {
52 diskbufp = alloc(DISKBUFSIZE);
53 #ifndef EFIBOOT
54 if (((uintptr_t)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) {
55 printf("diskbufp %" PRIxPTR "\n", (uintptr_t)diskbufp);
56 panic("diskbuf crosses 64k boundary");
57 }
58 #endif
59 }
60 return diskbufp;
61 }
62