#include "sys.h"
#include "proc.h"
#include "con.h"

/*
 * kread() and kwrite() comprise the memory device.
 * minor device numbers 0 and 1 are defined.
 * minor 0 is for i/o to outer space
 * direct to the 24-bit external memory bus.
 * minor 1 is for i/o to kernel space.
 */


#define K4(x)	(4096 - ((UINT)(x) & 4095))

/*
 * The size of a Morrow MPZ80 memory map address segment.
 */

#define SEGSIZE 4096

kread(dev)
	{
	krw(dev, READ);
	}

kwrite(dev)
	{
	krw(dev, WRITE);
	}

/*
 * Note that iomove can take 4K as a maximum byte count.
 */

	static
krw(dev, rw)
	int rw;
	{
	static UINT n;

	if (dev & 1)
		{	/* kernel space */
		while (u.count)
			{
			iomove(rw,(char *) (u.offset), min (u.count, SEGSIZE));
			}
		}

	else		/* outer space */
		{
		while (u.count)
			{
			n = u.count;
			n = min(n, K4(u.base));
			n = min(n, K4(u.offset));

			memrw(u.base, u.offset, rw, n);

			u.offset += n;
			u.base += n;
			u.count -= n;
			}
		}
	}

ioread(dev)
	int dev;
	{
	iorw(dev, READ);
	}

iowrite(dev)
	int dev;
	{
	iorw(dev, WRITE);
	}

iorw(dev, rw)
	int dev, rw;
	{
	static UCHAR port;

	port = minor(dev);
	if (port == 0)
		port = u.offset;
	while (u.count)
		{
		if (rw == READ)
			putbyte(in(port), u.base);
		else
			out(port, getbyte(u.base));
		u.base++;
		u.count--;
		}
	}