/* ES40 emulator.
 * Copyright (C) 2007-2008 by the ES40 Emulator Project
 *
 * WWW    : http://sourceforge.net/projects/es40
 * E-mail : camiel@camicom.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Although this is not required, the author would appreciate being notified of,
 * and receiving any modifications you may make to the source code that might serve
 * the general public.
 */

 /**
  * \file
  * Contains definitions for the SCSI bus class.
  *
  * $Id$
  *
  * X-1.4        Camiel Vanderhoeven                             14-MAR-2008
  *   1. More meaningful exceptions replace throwing (int) 1.
  *   2. U64 macro replaces X64 macro.
  *
  * X-1.3        Brian Wheeler                                   27-FEB-2008
  *      Avoid compiler warnings.
  *
  * X-1.2        Camiel Vanderhoeven                             16-FEB-2008
  *      Owner of the SCSI bus is allowed to re-arbitrate for it.
  *
  * X-1.1        Camiel Vanderhoeven                             12-JAN-2008
  *      Initial version in CVS.
  **/
#include "StdAfx.h"
#include "SCSIBus.h"

  /**
   * \brief Constructor.
   *
   * Initialize all disks to non-existing.
   **/
CSCSIBus::CSCSIBus(CConfigurator* cfg, CSystem* c) : CSystemComponent(cfg, c)
{
	int i;
	for (i = 0; i < 16; i++)
		targets[i] = 0;

	state.phase = SCSI_PHASE_FREE;
	state.target = -1;
	state.initiator = -1;
}

/**
 * \brief Destructor.
 **/
CSCSIBus::~CSCSIBus(void)
{
}

/**
 * \brief Register a SCSI device.
 *
 * Register a SCSI device as responding to a specific SCSI id.
 **/
void CSCSIBus::scsi_register(CSCSIDevice* dev, int bus, int target)
{
	if (targets[target] && targets[target] != dev)
		FAILURE(IllegalState, "More than one SCSI device at the same ID");
	targets[target] = dev;
	target_bus_no[target] = bus;
}

/**
 * \brief Unregister a SCSI device.
 *
 * Unregister a SCSI device as responding to a specific SCSI id. Needed
 * for some controllers if software changes it's SCSI id.
 **/
void CSCSIBus::scsi_unregister(CSCSIDevice* dev, int target)
{
	if (targets[target] != dev)
		FAILURE(IllegalState, "Attempt to unregister other SCSI device");
	targets[target] = 0;
}

/**
 * \brief Arbitrate for the SCSI bus.
 *
 * Returns true on succesful arbitration.
 * Arbitration succeeds if the bus is free.
 **/
bool CSCSIBus::arbitrate(int initiator)
{
	if (state.phase != SCSI_PHASE_FREE && state.initiator != initiator)
	{
		printf("Could not arbitrate for the SCSI bus.\n");
		return false;
	}

	state.initiator = initiator;
	state.phase = SCSI_PHASE_ARBITRATION;
	return true;
}

/**
 * \brief Select a device as a target.
 *
 * Returns true on succesful selection (= if the device responds to the select
 * by changing the SCSI phase.
 * The initiator calling this function should have succesfully arbitrated
 * for the SCSI bus first.
 **/
bool CSCSIBus::select(int initiator, int target)
{
	if (state.phase != SCSI_PHASE_ARBITRATION || state.initiator != initiator)
		FAILURE(IllegalState,
			"Attempt to select while the device has not won SCSI arbitration");

	if (!targets[target])
		return false;

	state.target = target;
	targets[target]->scsi_select_me(target_bus_no[target]);
	return(state.phase >= 0);
}

/**
 * \brief Change the SCSI phase.
 *
 * Only the selected target can do this.
 **/
void CSCSIBus::set_phase(int target, int phase)
{
	if (targets[target] != targets[state.target])
		FAILURE(IllegalState,
			"Attempt to set phase while the device has not been selected");

	state.phase = phase;
}

/**
 * \brief Release the SCSI bus.
 *
 * In the Arbitration phase, only the initiator can do this; otherwise,
 * only the selected target can do this.
 **/
void CSCSIBus::free_bus(int initiator)
{

	// nothing to do
	if (state.phase == SCSI_PHASE_FREE)
		return;

	if (state.phase == SCSI_PHASE_ARBITRATION)
	{
		if (initiator != state.initiator)
			FAILURE(IllegalState, "Attempt to free the scsi bus");
	}
	else
	{
		if (targets[initiator] != targets[state.target])
			FAILURE(IllegalState, "Attempt to free the scsi bus");
	}

	state.phase = SCSI_PHASE_FREE;
}

static u32  scsi_magic1 = 0x5C510123;
static u32  scsi_magic2 = 0x32105c51;

/**
 * Save state to a Virtual Machine State file.
 **/
int CSCSIBus::SaveState(FILE* f)
{
	long  ss = sizeof(state);

	fwrite(&scsi_magic1, sizeof(u32), 1, f);
	fwrite(&ss, sizeof(long), 1, f);
	fwrite(&state, sizeof(state), 1, f);
	fwrite(&scsi_magic2, sizeof(u32), 1, f);
	printf("%s: %d bytes saved.\n", devid_string, (int)ss);
	return 0;
}

/**
 * Restore state from a Virtual Machine State file.
 **/
int CSCSIBus::RestoreState(FILE* f)
{
	long    ss;
	u32     m1;
	u32     m2;
	size_t  r;

	r = fread(&m1, sizeof(u32), 1, f);
	if (r != 1)
	{
		printf("%s: unexpected end of file!\n", devid_string);
		return -1;
	}

	if (m1 != scsi_magic1)
	{
		printf("%s: MAGIC 1 does not match!\n", devid_string);
		return -1;
	}

	fread(&ss, sizeof(long), 1, f);
	if (r != 1)
	{
		printf("%s: unexpected end of file!\n", devid_string);
		return -1;
	}

	if (ss != sizeof(state))
	{
		printf("%s: STRUCT SIZE does not match!\n", devid_string);
		return -1;
	}

	fread(&state, sizeof(state), 1, f);
	if (r != 1)
	{
		printf("%s: unexpected end of file!\n", devid_string);
		return -1;
	}

	r = fread(&m2, sizeof(u32), 1, f);
	if (r != 1)
	{
		printf("%s: unexpected end of file!\n", devid_string);
		return -1;
	}

	if (m2 != scsi_magic2)
	{
		printf("%s: MAGIC 1 does not match!\n", devid_string);
		return -1;
	}

	printf("%s: %d bytes restored.\n", devid_string, (int)ss);
	return 0;
}
