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/*  This file is part of the program GDB, the GNU debugger.

    Copyright (C) 1998, 2007, 2008 Free Software Foundation, Inc.

    Contributed by Cygnus Solutions.

    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 3 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, see <http://www.gnu.org/licenses/>.

    */

#include "sim-main.h"

#include "hw-main.h"

/* DEVICE

   tx3904cpu - tx3904 cpu virtual device

   DESCRIPTION

   Implements the external tx3904 functionality.  This includes the

   delivery of of interrupts generated from other devices and the

   handling of device specific registers.

   PROPERTIES

   none

   PORTS

   reset (input)

   Currently ignored.

   nmi (input)

   Deliver a non-maskable interrupt to the processor.

   level (input)

   Deliver a maskable interrupt of given level, corresponding to

   IP[5:0], to processor.

   BUGS

   When delivering an interrupt, this code assumes that there is only

   one processor (number 0).

   This code does not attempt to be efficient at handling pending

   interrupts.  It simply schedules the interrupt delivery handler

   every instruction cycle until all pending interrupts go away.  An

   alternative implementation might modify instructions that change

   the PSW and have them check to see if the change makes an interrupt

   delivery possible.

   */

struct tx3904cpu {

  /* Pending interrupts for delivery by event handler */

  int pending_reset, pending_nmi, pending_level;

  struct hw_event* event;

};

/* input port ID's */

enum {

  RESET_PORT,

  NMI_PORT,

  LEVEL_PORT,

};

static const struct hw_port_descriptor tx3904cpu_ports[] = {

  /* interrupt inputs */

  { "reset", RESET_PORT, 0, input_port, },

  { "nmi", NMI_PORT, 0, input_port, },

  { "level", LEVEL_PORT, 0, input_port, },

  { NULL, },

};

/* Finish off the partially created hw device.  Attach our local

   callbacks.  Wire up our port names etc */

static hw_port_event_method tx3904cpu_port_event;

static void

tx3904cpu_finish (struct hw *me)

{

  struct tx3904cpu *controller;

  controller = HW_ZALLOC (me, struct tx3904cpu);

  set_hw_data (me, controller);

  set_hw_ports (me, tx3904cpu_ports);

  set_hw_port_event (me, tx3904cpu_port_event);

  /* Initialize the pending interrupt flags */

  controller->pending_level = 0;

  controller->pending_reset = 0;

  controller->pending_nmi = 0;

  controller->event = NULL;

}

/* An event arrives on an interrupt port */

static void

deliver_tx3904cpu_interrupt (struct hw *me,

                            void *data)

{

  struct tx3904cpu *controller = hw_data (me);

  SIM_DESC sd = hw_system (me);

  sim_cpu *cpu = STATE_CPU (sd, 0); /* NB: fix CPU 0. */

  address_word cia = CIA_GET (cpu);

#define CPU cpu

#define SD current_state

  if (controller->pending_reset)

    {

      controller->pending_reset = 0;

      HW_TRACE ((me, "reset pc=0x%08lx", (long) CIA_GET (cpu)));

      SignalExceptionNMIReset();

    }

  else if (controller->pending_nmi)

    {

      controller->pending_nmi = 0;

      HW_TRACE ((me, "nmi pc=0x%08lx", (long) CIA_GET (cpu)));

      SignalExceptionNMIReset();

    }

  else if (controller->pending_level)

    {

      HW_TRACE ((me, "interrupt level=%d pc=0x%08lx sr=0x%08lx",

                 controller->pending_level,

                 (long) CIA_GET (cpu), (long) SR));

      /* Clear CAUSE register.  It may stay this way if the interrupt

         was cleared with a negative pending_level. */

      CAUSE &= ~ (cause_IP_mask << cause_IP_shift);

      if(controller->pending_level > 0) /* interrupt set */

        {

          /* set hardware-interrupt subfields of CAUSE register */

          CAUSE |= (controller->pending_level & cause_IP_mask) << cause_IP_shift;

          /* check for enabled / unmasked interrupts */

          if((SR & status_IEc) &&

             (controller->pending_level & ((SR >> status_IM_shift) & status_IM_mask)))

            {

              controller->pending_level = 0;

              SignalExceptionInterrupt(0 /* dummy value */);

            }

          else

            {

              /* reschedule soon */

              if(controller->event != NULL)

                hw_event_queue_deschedule(me, controller->event);

              controller->event =

                hw_event_queue_schedule (me, 1, deliver_tx3904cpu_interrupt, NULL);

            }

        } /* interrupt set */

    }

#undef CPU cpu

#undef SD current_state

}

static void

tx3904cpu_port_event (struct hw *me,

                     int my_port,

                     struct hw *source,

                     int source_port,

                     int level)

{

  struct tx3904cpu *controller = hw_data (me);

  switch (my_port)

    {

    case RESET_PORT:

      controller->pending_reset = 1;

      HW_TRACE ((me, "port-in reset"));

      break;

    case NMI_PORT:

      controller->pending_nmi = 1;

      HW_TRACE ((me, "port-in nmi"));

      break;

    case LEVEL_PORT:

      /* level == 0 means that the interrupt was cleared */

      if(level == 0)

        controller->pending_level = -1; /* signal end of interrupt */

      else

        controller->pending_level = level;

      HW_TRACE ((me, "port-in level=%d", level));

      break;

    default:

      hw_abort (me, "bad switch");

      break;

    }

  /* Schedule an event to be delivered immediately after current

     instruction. */

  if(controller->event != NULL)

    hw_event_queue_deschedule(me, controller->event);

  controller->event =

    hw_event_queue_schedule (me, 0, deliver_tx3904cpu_interrupt, NULL);

}

const struct hw_descriptor dv_tx3904cpu_descriptor[] = {

  { "tx3904cpu", tx3904cpu_finish, },

  { NULL },

};