hpemung/src/timers.c

/*
 *     /
 *    /__  ___  ___  ____
 *   /  / /  / /__/ / / / /  /
 *  /  / /__/ /__  /   / /__/
 *      /
 *     /    version 0.9.0
 *
 * Copyright 2002 Daniel Nilsson
 *
 * This file is part of hpemu.
 *
 * Hpemu 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.
 *
 * Hpemu 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 hpemu; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "types.h"
#include "cpu.h"
#include "timers.h"

#define TIMER1_EXTRA 0x1
#define TIMER1_INT 0x2
#define TIMER1_WAKE 0x4
#define TIMER1_SRQ 0x8

#define TIMER_RUN 0x1
#define TIMER2_INT 0x2
#define TIMER2_WAKE 0x4
#define TIMER2_SRQ 0x8

byte timer1_control;
byte timer2_control;
byte timer1_value;
dword timer2_value;

void timer1_update( void )
{
    if ( timer2_control & TIMER_RUN ) {
        timer1_value--;
        timer1_value &= 0xF;

        if ( timer1_value & 0x8 ) {
            if ( timer1_control & TIMER1_WAKE ) {
                timer1_control |= TIMER1_SRQ;

                if ( cpu.shutdown ) {
                    cpu.shutdown = FALSE;
                    timer1_control &= ~TIMER1_WAKE;
                }
            }
            if ( timer1_control & TIMER1_INT ) {
                timer1_control |= TIMER1_SRQ;

                if ( !cpu.shutdown ) {
                    cpu_interrupt();
                }
            }
        } else {
            timer1_control &= ~TIMER1_SRQ;
        }
    }
}

void timer2_update( void )
{
    if ( timer2_control & TIMER_RUN ) {
        timer2_value--;
        if ( timer2_value & 0x80000000 ) {
            if ( timer2_control & TIMER2_WAKE ) {
                timer2_control |= TIMER2_SRQ;
                if ( cpu.shutdown ) {
                    cpu.shutdown = 0;
                    timer2_control &= ~TIMER2_WAKE;
                }
            }
            if ( timer2_control & TIMER2_INT ) {
                timer2_control |= TIMER2_SRQ;
                if ( !cpu.shutdown ) {
                    cpu_interrupt();
                }
            }
        } else {
            timer2_control &= ~TIMER2_SRQ;
        }
    }
}