1 /* $NetBSD: diskbuf.c,v 1.6 2005/12/11 12:17:48 christos 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 <lib/libsa/stand.h> 32 #include "diskbuf.h" 33 34 char *diskbufp; /* allocated from heap */ 35 36 const void *diskbuf_user; 37 38 /* 39 * Global shared "diskbuf" is used as read ahead buffer. 40 * This MAY have to not cross a 64k boundary. 41 * In practise it is allocated out of the heap early on... 42 * NB a statically allocated diskbuf is not guaranteed to not 43 * cross a 64k boundary. 44 */ 45 char * 46 alloc_diskbuf(const void *user) 47 { 48 diskbuf_user = user; 49 if (!diskbufp) { 50 diskbufp = alloc(DISKBUFSIZE); 51 if (((int)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) { 52 printf("diskbufp %x\n", (unsigned)diskbufp); 53 panic("diskbuf crosses 64k boundary"); 54 } 55 } 56 return diskbufp; 57 } 58