SCSIBus.cpp

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/* 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.
 */

#include "StdAfx.h"
#include "SCSIBus.h"

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;
}

CSCSIBus::~CSCSIBus(void)
{ }

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;
}

void CSCSIBus::scsi_unregister(CSCSIDevice* dev, int target)
{
  if(targets[target] != dev)
    FAILURE(IllegalState, "Attempt to unregister other SCSI device");
  targets[target] = 0;
}

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;
}

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);
}

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;
}

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;

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;
}

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;
}

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