mem.c

来自「unix v7是最后一个广泛发布的研究型UNIX版本」· C语言 代码 · 共 71 行

#
/*
 */

/*
 *	Memory special file
 *	minor device 0 is physical memory
 *	minor device 1 is kernel memory
 *	minor device 2 is EOF/RATHOLE
 */

#include "../h/param.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/conf.h"
#include "../h/seg.h"

mmread(dev)
{
	register c, bn, on;
	int a, d;

	if(minor(dev) == 2)
		return;
	do {
		bn = u.u_offset >> 6;
		on = u.u_offset & 077;
		a = UISA->r[0];
		d = UISD->r[0];
		spl7();
		UISA->r[0] = bn;
		UISD->r[0] = 077406;
		if(minor(dev) == 1)
			UISA->r[0] = (ka6-6)->r[(bn>>7)&07] + (bn & 0177);
		if ((c = fuibyte((caddr_t)on)) < 0)
			u.u_error = ENXIO;
		UISA->r[0] = a;
		UISD->r[0] = d;
		spl0();
	} while(u.u_error==0 && passc(c)>=0);
}

mmwrite(dev)
{
	register c, bn, on;
	int a, d;

	if(minor(dev) == 2) {
		u.u_count = 0;
		return;
	}
	for(;;) {
		bn = u.u_offset >> 6;
		on = u.u_offset & 077;
		if ((c=cpass())<0 || u.u_error!=0)
			break;
		a = UISA->r[0];
		d = UISD->r[0];
		spl7();
		UISA->r[0] = bn;
		UISD->r[0] = 077406;
		if(minor(dev) == 1)
			UISA->r[0] = (ka6-6)->r[(bn>>7)&07] + (bn & 0177);
		if (suibyte((caddr_t)on, c) < 0)
			u.u_error = ENXIO;
		UISA->r[0] = a;
		UISD->r[0] = d;
		spl0();
	}
}