1*58a2b000SEvgeniy Ivanov /* $NetBSD: diskbuf.c,v 1.6 2005/12/11 12:17:48 christos Exp $ */
2*58a2b000SEvgeniy Ivanov
3*58a2b000SEvgeniy Ivanov /*
4*58a2b000SEvgeniy Ivanov * Copyright (c) 1996
5*58a2b000SEvgeniy Ivanov * Matthias Drochner. All rights reserved.
6*58a2b000SEvgeniy Ivanov *
7*58a2b000SEvgeniy Ivanov * Redistribution and use in source and binary forms, with or without
8*58a2b000SEvgeniy Ivanov * modification, are permitted provided that the following conditions
9*58a2b000SEvgeniy Ivanov * are met:
10*58a2b000SEvgeniy Ivanov * 1. Redistributions of source code must retain the above copyright
11*58a2b000SEvgeniy Ivanov * notice, this list of conditions and the following disclaimer.
12*58a2b000SEvgeniy Ivanov * 2. Redistributions in binary form must reproduce the above copyright
13*58a2b000SEvgeniy Ivanov * notice, this list of conditions and the following disclaimer in the
14*58a2b000SEvgeniy Ivanov * documentation and/or other materials provided with the distribution.
15*58a2b000SEvgeniy Ivanov *
16*58a2b000SEvgeniy Ivanov * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17*58a2b000SEvgeniy Ivanov * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18*58a2b000SEvgeniy Ivanov * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19*58a2b000SEvgeniy Ivanov * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20*58a2b000SEvgeniy Ivanov * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21*58a2b000SEvgeniy Ivanov * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22*58a2b000SEvgeniy Ivanov * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23*58a2b000SEvgeniy Ivanov * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24*58a2b000SEvgeniy Ivanov * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25*58a2b000SEvgeniy Ivanov * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*58a2b000SEvgeniy Ivanov *
27*58a2b000SEvgeniy Ivanov */
28*58a2b000SEvgeniy Ivanov
29*58a2b000SEvgeniy Ivanov /* data buffer for BIOS disk / DOS I/O */
30*58a2b000SEvgeniy Ivanov
31*58a2b000SEvgeniy Ivanov #include <lib/libsa/stand.h>
32*58a2b000SEvgeniy Ivanov #include "diskbuf.h"
33*58a2b000SEvgeniy Ivanov
34*58a2b000SEvgeniy Ivanov char *diskbufp; /* allocated from heap */
35*58a2b000SEvgeniy Ivanov
36*58a2b000SEvgeniy Ivanov const void *diskbuf_user;
37*58a2b000SEvgeniy Ivanov
38*58a2b000SEvgeniy Ivanov /*
39*58a2b000SEvgeniy Ivanov * Global shared "diskbuf" is used as read ahead buffer.
40*58a2b000SEvgeniy Ivanov * This MAY have to not cross a 64k boundary.
41*58a2b000SEvgeniy Ivanov * In practise it is allocated out of the heap early on...
42*58a2b000SEvgeniy Ivanov * NB a statically allocated diskbuf is not guaranteed to not
43*58a2b000SEvgeniy Ivanov * cross a 64k boundary.
44*58a2b000SEvgeniy Ivanov */
45*58a2b000SEvgeniy Ivanov char *
alloc_diskbuf(const void * user)46*58a2b000SEvgeniy Ivanov alloc_diskbuf(const void *user)
47*58a2b000SEvgeniy Ivanov {
48*58a2b000SEvgeniy Ivanov diskbuf_user = user;
49*58a2b000SEvgeniy Ivanov if (!diskbufp) {
50*58a2b000SEvgeniy Ivanov diskbufp = alloc(DISKBUFSIZE);
51*58a2b000SEvgeniy Ivanov if (((int)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) {
52*58a2b000SEvgeniy Ivanov printf("diskbufp %x\n", (unsigned)diskbufp);
53*58a2b000SEvgeniy Ivanov panic("diskbuf crosses 64k boundary");
54*58a2b000SEvgeniy Ivanov }
55*58a2b000SEvgeniy Ivanov }
56*58a2b000SEvgeniy Ivanov return diskbufp;
57*58a2b000SEvgeniy Ivanov }
58