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/* This file is part of the program GDB, the GNU debugger.
Copyright (C) 1998-2020 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 = CPU_PC_GET (cpu);
#define CPU cpu
#define SD sd
if (controller->pending_reset)
{
controller->pending_reset = 0;
HW_TRACE ((me, "reset pc=0x%08lx", (long) CPU_PC_GET (cpu)));
SignalExceptionNMIReset();
}
else if (controller->pending_nmi)
{
controller->pending_nmi = 0;
HW_TRACE ((me, "nmi pc=0x%08lx", (long) CPU_PC_GET (cpu)));
SignalExceptionNMIReset();
}
else if (controller->pending_level)
{
HW_TRACE ((me, "interrupt level=%d pc=0x%08lx sr=0x%08lx",
controller->pending_level,
(long) CPU_PC_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
#undef SD
}
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 },
};
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