SCSIBus.cpp

/* 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: SCSIBus.cpp,v 1.3 2008/02/27 12:04:26 iamcamiel Exp $
 *
 * 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("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("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("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("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("Attempt to free the scsi bus");
  }
  else
  {
    if (targets[initiator]!=targets[state.target])
      FAILURE("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;
}