1 /* $NetBSD: diskbuf.c,v 1.3 2003/04/02 10:39:33 fvdl 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 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed for the NetBSD Project 18 * by Matthias Drochner. 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. 21 * 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. 32 * 33 */ 34 35 /* data buffer for BIOS disk / DOS I/O */ 36 37 #include "diskbuf.h" 38 #include "stand.h" 39 40 char *diskbufp; /* allocated from heap */ 41 42 const void *diskbuf_user; 43 44 /* 45 * Global shared "diskbuf" is used as read ahead buffer. 46 * This MAY have to not cross a 64k boundary. 47 * In practise it is allocated out of the heap early on... 48 * NB a statically allocated diskbuf is not guaranteed to not 49 * cross a 64k boundary. 50 */ 51 char * 52 alloc_diskbuf(const void *user) 53 { 54 diskbuf_user = user; 55 if (!diskbufp) { 56 diskbufp = alloc(DISKBUFSIZE); 57 if (((int)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) { 58 printf("diskbufp %x\n", (unsigned)diskbufp); 59 panic("diskbuf crosses 64k boundary"); 60 } 61 } 62 return diskbufp; 63 } 64