asio.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)asio.c	4.1	(ULTRIX)	7/3/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1985 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 *	Copyright (c) 1982 Regents of the University of California
 */

#include <stdio.h>
#include "as.h"
/*
 *	Block I/O routines for logical I/O concurrently in
 *	more than one place in the same file.
 */
int	biofd;			/* file descriptor for block I/O file */
int	biobufsize;		/* optimal block size for I/O */
off_t	boffset;		/* physical position in logical file */
BFILE	*biobufs;		/* the block I/O buffers */

#define	error(severity, message) \
	{yyerror(message); if (severity) delexit();}

Flushfield(n)
	register int n;
{
	while (n>0) {
		outb(bitfield);
		bitfield >>= 8;
		n -= 8;
	}
	bitoff=0;
	bitfield=0;
}

/*
 *	Block I/O Routines
 */
bopen(bp, off)
	struct biobuf *bp;
	off_t	off;
{

	bp->b_ptr = bp->b_buf = Calloc(1,biobufsize);
	bp->b_nleft = biobufsize - off % biobufsize;
	bp->b_off = off;
	bp->b_link = biobufs;
	biobufs = bp;
}

int	bwrerror;

bwrite(p, cnt, bp)
	register char *p;
	register int cnt;
	register struct biobuf *bp;
{
	register int put;
	register char *to;

top:
	if (cnt == 0)
		return;
	if (bp->b_nleft) {
		put = bp->b_nleft;
		if (put > cnt)
			put = cnt;
		bp->b_nleft -= put;
		to = bp->b_ptr;
#ifdef lint
		*to = *to;
#endif lint
		asm("movc3 r8,(r11),(r7)");
		bp->b_ptr += put;
		p += put;
		cnt -= put;
		goto top;
	}
	if (cnt >= biobufsize) {
		if (bp->b_ptr != bp->b_buf)
			bflush1(bp);
		put = cnt - cnt % biobufsize;
		if (boffset != bp->b_off)
			(void)lseek(biofd, (long)bp->b_off, 0);
		if (write(biofd, p, put) != put) {
			bwrerror = 1;
			error(1, "Output write error");
		}
		bp->b_off += put;
		boffset = bp->b_off;
		p += put;
		cnt -= put;
		goto top;
	}
	bflush1(bp);
	goto top;
}

bflush()
{
	register struct biobuf *bp;

	if (bwrerror)
		return;
	for (bp = biobufs; bp; bp = bp->b_link)
		bflush1(bp);
}

bflush1(bp)
	register struct biobuf *bp;
{
	register int cnt = bp->b_ptr - bp->b_buf;

	if (cnt == 0)
		return;
	if (boffset != bp->b_off)
		(void)lseek(biofd, (long)bp->b_off, 0);
	if (write(biofd, bp->b_buf, cnt) != cnt) {
		bwrerror = 1;
		error(1, "Output write error");
	}
	bp->b_off += cnt;
	boffset = bp->b_off;
	bp->b_ptr = bp->b_buf;
	bp->b_nleft = biobufsize;
}

bflushc(bp, c)
	register struct biobuf *bp;
	char	c;
{
	bflush1(bp);
	bputc(c, bp);
}