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// license:BSD-3-Clause
// copyright-holders:Mike Balfour
/***************************************************************************
Atari Subs hardware
***************************************************************************/
#include "emu.h"
#include "includes/subs.h"
/***************************************************************************
machine initialization
***************************************************************************/
void subs_state::machine_start()
{
save_item(NAME(m_steering_buf1));
save_item(NAME(m_steering_buf2));
save_item(NAME(m_steering_val1));
save_item(NAME(m_steering_val2));
save_item(NAME(m_last_val_1));
save_item(NAME(m_last_val_2));
}
void subs_state::machine_reset()
{
m_steering_buf1 = 0;
m_steering_buf2 = 0;
m_steering_val1 = 0x00;
m_steering_val2 = 0x00;
}
/***************************************************************************
interrupt
***************************************************************************/
INTERRUPT_GEN_MEMBER(subs_state::interrupt)
{
/* only do NMI interrupt if not in TEST mode */
if ((ioport("IN1")->read() & 0x40)==0x40)
device.execute().pulse_input_line(INPUT_LINE_NMI, attotime::zero);
}
/***************************************************************************
Steering
When D7 is high, the steering wheel has moved.
If D6 is high, it moved left. If D6 is low, it moved right.
Be sure to keep returning a direction until steer_reset is called.
***************************************************************************/
int subs_state::steering_1()
{
int this_val;
int delta;
this_val=ioport("DIAL2")->read();
delta=this_val-m_last_val_1;
m_last_val_1=this_val;
if (delta>128) delta-=256;
else if (delta<-128) delta+=256;
/* Divide by four to make our steering less sensitive */
m_steering_buf1+=(delta/4);
if (m_steering_buf1>0)
{
m_steering_buf1--;
m_steering_val1=0xC0;
}
else if (m_steering_buf1<0)
{
m_steering_buf1++;
m_steering_val1=0x80;
}
return m_steering_val1;
}
int subs_state::steering_2()
{
int this_val;
int delta;
this_val=ioport("DIAL1")->read();
delta=this_val-m_last_val_2;
m_last_val_2=this_val;
if (delta>128) delta-=256;
else if (delta<-128) delta+=256;
/* Divide by four to make our steering less sensitive */
m_steering_buf2+=(delta/4);
if (m_steering_buf2>0)
{
m_steering_buf2--;
m_steering_val2=0xC0;
}
else if (m_steering_buf2<0)
{
m_steering_buf2++;
m_steering_val2=0x80;
}
return m_steering_val2;
}
/***************************************************************************
steer_reset
***************************************************************************/
WRITE8_MEMBER(subs_state::steer_reset_w)
{
m_steering_val1 = 0x00;
m_steering_val2 = 0x00;
}
/***************************************************************************
control_r
***************************************************************************/
READ8_MEMBER(subs_state::control_r)
{
int inport = ioport("IN0")->read();
switch (offset & 0x07)
{
case 0x00: return ((inport & 0x01) << 7); /* diag step */
case 0x01: return ((inport & 0x02) << 6); /* diag hold */
case 0x02: return ((inport & 0x04) << 5); /* slam */
case 0x03: return ((inport & 0x08) << 4); /* spare */
case 0x04: return ((steering_1() & 0x40) << 1); /* steer dir 1 */
case 0x05: return ((steering_1() & 0x80) << 0); /* steer flag 1 */
case 0x06: return ((steering_2() & 0x40) << 1); /* steer dir 2 */
case 0x07: return ((steering_2() & 0x80) << 0); /* steer flag 2 */
}
return 0;
}
/***************************************************************************
coin_r
***************************************************************************/
READ8_MEMBER(subs_state::coin_r)
{
int inport = ioport("IN1")->read();
switch (offset & 0x07)
{
case 0x00: return ((inport & 0x01) << 7); /* coin 1 */
case 0x01: return ((inport & 0x02) << 6); /* start 1 */
case 0x02: return ((inport & 0x04) << 5); /* coin 2 */
case 0x03: return ((inport & 0x08) << 4); /* start 2 */
case 0x04: return ((inport & 0x10) << 3); /* VBLANK */
case 0x05: return ((inport & 0x20) << 2); /* fire 1 */
case 0x06: return ((inport & 0x40) << 1); /* test */
case 0x07: return ((inport & 0x80) << 0); /* fire 2 */
}
return 0;
}
/***************************************************************************
options_r
***************************************************************************/
READ8_MEMBER(subs_state::options_r)
{
int opts = ioport("DSW")->read();
switch (offset & 0x03)
{
case 0x00: return ((opts & 0xC0) >> 6); /* language */
case 0x01: return ((opts & 0x30) >> 4); /* credits */
case 0x02: return ((opts & 0x0C) >> 2); /* game time */
case 0x03: return ((opts & 0x03) >> 0); /* extended time */
}
return 0;
}
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