mem.c

著名的AT&T UNIX v6 源码

/*
 *	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/buf.h"
#include "../h/systm.h"
#include "../h/page.h"
#include "../h/mtpr.h"

mmread(dev)
{
	register char *p;
	register c;
	extern int mmap[];
	extern char vmmap[];

	if(minor(dev) == 2)
		return;
	if( minor(dev) == 1 ) {
		if( kernacc(u.u_offset, u.u_count, B_READ)
	    && !copyout(u.u_offset, u.u_base, u.u_count) ) {
		c = u.u_count;
		u.u_count = 0;
		u.u_base += c;
		u.u_offset += c;
	} else 
		u.u_error = EFAULT;
	return;
	}

	if( minor(dev) == 0) {
		while (u.u_count > 0 && u.u_error == 0) {
			c = (int) u.u_offset >> 9;
			if( c < 0 || c >= MAXMEM ) {
				u.u_error = EFAULT;
				break;
			}
			*mmap = c | (PG_V | PG_KR);
			mtpr(TBIS, vmmap);
			copyout(vmmap+((int)u.u_offset & 0x1ff), u.u_base, c=min(512-((int)u.u_offset & 0x1ff), u.u_count));
			u.u_count -= c;
			u.u_base += c;
			u.u_offset += c;
		}
	return;
	}
 
	if (minor(dev) == 3) { /* UNIBUS access */
		if ((!kernacc(u.u_offset,u.u_count,B_READ)) ||
		(!useracc(u.u_base,u.u_count,B_READ)) ||
		UNIcpy(u.u_offset,u.u_base,u.u_count,B_READ))
		  u.u_error = EFAULT;
		else {
			u.u_offset += u.u_count;
			u.u_base += u.u_count;
			u.u_count = 0;
		}
		return;
	}
}

mmwrite(dev)
{
	register char *p;
	register c;

	if(minor(dev) == 2) {
		c = u.u_count;
		u.u_count = 0;
		u.u_offset += c;
		return;
	}
	/*  kernel virt mem */
	if (minor(dev) == 1) {
		if ((!kernacc(u.u_offset,u.u_count,B_WRITE)) || copyin(u.u_base,u.u_offset,u.u_count))
			u.u_error = EFAULT;
		else {
			u.u_offset += u.u_count;
			u.u_base += u.u_count;
			u.u_count = 0 ;
		}
		return;
	}
 
	if (minor(dev) == 3) { /* UNIBUS access */
		if ((!kernacc(u.u_offset,u.u_count,B_WRITE)) ||
		(!useracc(u.u_base,u.u_count,B_WRITE)) ||
		UNIcpy(u.u_offset,u.u_base,u.u_count,B_WRITE))
			u.u_error = EFAULT;
		else {
			u.u_offset += u.u_count;
			u.u_base += u.u_count;
			u.u_count = 0;
		}
		return;
	}
}

/*
 *  UNIBUS Address Space <-->  User Space transfer
 */
UNIcpy(uniadd,usradd,bknt,direct)
short *uniadd , *usradd;
{
	register short *from , *to;
	register int i;
 
	if (direct == B_READ) {
		from = uniadd;
		to = usradd ;
	} else {
		if (direct == B_WRITE) {
			from = usradd;
			to = uniadd ;
		}
	}
 
	for (i = (bknt>>1) ; i>0 ; i--)
		(*to++) = (*from++);
	return(0);
}