58 lines
2.1 KiB
C
58 lines
2.1 KiB
C
/* $NetBSD: diskbuf.c,v 1.6 2005/12/11 12:17:48 christos Exp $ */
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/*
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* Copyright (c) 1996
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* Matthias Drochner. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/* data buffer for BIOS disk / DOS I/O */
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#include <lib/libsa/stand.h>
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#include "diskbuf.h"
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char *diskbufp; /* allocated from heap */
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const void *diskbuf_user;
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/*
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* Global shared "diskbuf" is used as read ahead buffer.
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* This MAY have to not cross a 64k boundary.
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* In practise it is allocated out of the heap early on...
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* NB a statically allocated diskbuf is not guaranteed to not
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* cross a 64k boundary.
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*/
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char *
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alloc_diskbuf(const void *user)
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{
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diskbuf_user = user;
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if (!diskbufp) {
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diskbufp = alloc(DISKBUFSIZE);
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if (((int)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) {
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printf("diskbufp %x\n", (unsigned)diskbufp);
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panic("diskbuf crosses 64k boundary");
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}
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}
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return diskbufp;
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}
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