/*
	IWMEVDEV.c

	Copyright (C) 2006 Philip Cummins, Paul C. Pratt

	You can redistribute this file and/or modify it under the terms
	of version 2 of the GNU General Public License as published by
	the Free Software Foundation.  You should have received a copy
	of the license along with this file; see the file COPYING.

	This file is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	license for more details.
*/

/*
	Integrated Woz Machine EMulated DEVice

	Emulates the IWM found in the Mac Plus.

	This code is adapted from "IWM.c" in vMac by Philip Cummins.
*/

/*
	This is the emulation for the IWM, the Integrated Woz Machine.
	It's basically a serial to parallel converter with some timing
	in-built into it to perform handshaking. Emulation so far just
	includes Status and Mode Register Accesses.
*/

#ifndef AllFiles
#include "SYSDEPNS.h"

#include "MYOSGLUE.h"
#include "EMCONFIG.h"
#include "GLOBGLUE.h"
#endif

#include "IWMEMDEV.h"

#define kph0L     0x00 /* CA0 off (0) */
#define kph0H     0x01 /* CA0 on (1) */
#define kph1L     0x02 /* CA1 off (0) */
#define kph1H     0x03 /* CA1 on (1) */
#define kph2L     0x04 /* CA2 off (0) */
#define kph2H     0x05 /* CA2 on (1) */
#define kph3L     0x06 /* LSTRB off (low) */
#define kph3H     0x07 /* LSTRB on (high) */
#define kmtrOff   0x08 /* disk enable off */
#define kmtrOn    0x09 /* disk enable on */
#define kintDrive 0x0A /* select internal drive */
#define kextDrive 0x0B /* select external drive */
#define kq6L      0x0C /* Q6 off */
#define kq6H      0x0D /* Q6 on */
#define kq7L      0x0E /* Q7 off */
#define kq7H      0x0F /* Q7 on */

#define kph0 0x01
#define kph1 0x02
#define kph2 0x04
#define kph3 0x08
#define kmtr 0x10
#define kdrv 0x20
#define kq6  0x40
#define kq7  0x80

typedef struct
{
	ui3b DataIn;    /* Read Data Register */
	ui3b Handshake; /* Read Handshake Register */
	ui3b Status;    /* Read Status Register */
	ui3b Mode;
		/* Drive Off : Write Mode Register */
		/* Drive On  : Write Data Register */
	ui3b DataOut;   /* Write Data Register */
	ui3b Lines;     /* Used to Access Disk Drive Registers */
} IWM_Ty;

IWM_Ty IWM;

GLOBALPROC IWM_Reset(void)
{
	IWM.DataIn = IWM.Handshake = IWM.Status = IWM.Mode =
		IWM.DataOut = IWM.Lines = 0;
}

typedef enum {On, Off} Mode_Ty;

LOCALPROC IWM_Set_Lines(ui3b line, Mode_Ty the_mode)
{
	if (the_mode == Off) {
		IWM.Lines &= (0xFF - line);
	} else {
		IWM.Lines |= line;
	}
}

LOCALFUNC ui3b IWM_Read_Reg(void)
{
	switch ((IWM.Lines & (kq6 + kq7)) >> 6) {
		case 0 :
#if (CurEmMd >= kEmMd_SE) && (CurEmMd <= kEmMd_IIx)
			/* don't report */
#else
			ReportAbnormal("IWM Data Read");
#endif
#ifdef _IWM_Debug
			printf("IWM Data Read\n");
#endif
			return IWM.DataIn;
			break;
		case 1 :
#ifdef _IWM_Debug
			printf("IWM Status Read\n");
#endif
			return IWM.Status;
			break;
		case 2 :
			ReportAbnormal("IWM Handshake Read");
#ifdef _IWM_Debug
			printf("IWM Handshake Read\n");
#endif
			return IWM.Handshake;
			break;
		case 3 :
		default :
			/*
				should alway be in 0-3,
				but compiler warnings don't know that
			*/
			return 0;
			break;
	}
}

LOCALPROC IWM_Write_Reg(ui3b in)
{
	if (((IWM.Lines & kmtr) >> 4) == 0) {
#ifdef _IWM_Debug
		printf("IWM Mode Register Write\n");
#endif
		IWM.Mode = in;
		IWM.Status = ((IWM.Status & 0xE0) + (IWM.Mode & 0x1F));
	}
}

GLOBALFUNC ui5b IWM_Access(ui5b Data, blnr WriteMem, CPTR addr)
{
	switch (addr) {
		case kph0L :
			IWM_Set_Lines(kph0, Off);
			break;
		case kph0H :
			IWM_Set_Lines(kph0, On);
			break;
		case kph1L :
			IWM_Set_Lines(kph1, Off);
			break;
		case kph1H :
			IWM_Set_Lines(kph1, On);
			break;
		case kph2L :
			IWM_Set_Lines(kph2, Off);
			break;
		case kph2H :
			IWM_Set_Lines(kph2, On);
			break;
		case kph3L :
			IWM_Set_Lines(kph3, Off);
			break;
		case kph3H :
			IWM_Set_Lines(kph3, On);
			break;
		case kmtrOff :
			IWM.Status &= 0xDF;
			IWM_Set_Lines(kmtr, Off);
			break;
		case kmtrOn :
			IWM.Status |= 0x20;
			IWM_Set_Lines(kmtr, On);
			break;
		case kintDrive :
			IWM_Set_Lines(kdrv, Off);
			break;
		case kextDrive :
			IWM_Set_Lines(kdrv, On);
			break;
		case kq6L :
			IWM_Set_Lines(kq6, Off);
			break;
		case kq6H :
			IWM_Set_Lines(kq6, On);
			break;
		case kq7L :
			if (! WriteMem) {
				Data = IWM_Read_Reg();
			}
			IWM_Set_Lines(kq7, Off);
			break;
		case kq7H :
			if (WriteMem) {
				IWM_Write_Reg(Data);
			}
			IWM_Set_Lines(kq7, On);
			break;
	}

	return Data;
}