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/***************************************************************************
Atari Subs hardware
***************************************************************************/
#include "driver.h"
#include "subs.h"
static int subs_steering_buf1;
static int subs_steering_buf2;
static int subs_steering_val1;
static int subs_steering_val2;
/***************************************************************************
subs_init_machine
***************************************************************************/
MACHINE_RESET( subs )
{
subs_steering_buf1 = 0;
subs_steering_buf2 = 0;
subs_steering_val1 = 0x00;
subs_steering_val2 = 0x00;
}
/***************************************************************************
subs_interrupt
***************************************************************************/
INTERRUPT_GEN( subs_interrupt )
{
/* only do NMI interrupt if not in TEST mode */
if ((input_port_2_r(0) & 0x40)==0x40)
cpunum_set_input_line(0,INPUT_LINE_NMI,PULSE_LINE);
}
/***************************************************************************
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.
***************************************************************************/
static int subs_steering_1(void)
{
static int last_val=0;
int this_val;
int delta;
this_val=input_port_3_r(0);
delta=this_val-last_val;
last_val=this_val;
if (delta>128) delta-=256;
else if (delta<-128) delta+=256;
/* Divide by four to make our steering less sensitive */
subs_steering_buf1+=(delta/4);
if (subs_steering_buf1>0)
{
subs_steering_buf1--;
subs_steering_val1=0xC0;
}
else if (subs_steering_buf1<0)
{
subs_steering_buf1++;
subs_steering_val1=0x80;
}
return subs_steering_val1;
}
static int subs_steering_2(void)
{
static int last_val=0;
int this_val;
int delta;
this_val=input_port_4_r(0);
delta=this_val-last_val;
last_val=this_val;
if (delta>128) delta-=256;
else if (delta<-128) delta+=256;
/* Divide by four to make our steering less sensitive */
subs_steering_buf2+=(delta/4);
if (subs_steering_buf2>0)
{
subs_steering_buf2--;
subs_steering_val2=0xC0;
}
else if (subs_steering_buf2<0)
{
subs_steering_buf2++;
subs_steering_val2=0x80;
}
return subs_steering_val2;
}
/***************************************************************************
subs_steer_reset
***************************************************************************/
WRITE8_HANDLER( subs_steer_reset_w )
{
subs_steering_val1 = 0x00;
subs_steering_val2 = 0x00;
}
/***************************************************************************
subs_control_r
***************************************************************************/
READ8_HANDLER( subs_control_r )
{
int inport = input_port_1_r(offset);
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 ((subs_steering_1() & 0x40) << 1); /* steer dir 1 */
case 0x05: return ((subs_steering_1() & 0x80) << 0); /* steer flag 1 */
case 0x06: return ((subs_steering_2() & 0x40) << 1); /* steer dir 2 */
case 0x07: return ((subs_steering_2() & 0x80) << 0); /* steer flag 2 */
}
return 0;
}
/***************************************************************************
subs_coin_r
***************************************************************************/
READ8_HANDLER( subs_coin_r )
{
int inport = input_port_2_r(offset);
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;
}
/***************************************************************************
subs_options_r
***************************************************************************/
READ8_HANDLER( subs_options_r )
{
int opts = input_port_0_r(offset);
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;
}
/***************************************************************************
subs_lamp1_w
***************************************************************************/
WRITE8_HANDLER( subs_lamp1_w )
{
set_led_status(0,~offset & 1);
}
/***************************************************************************
subs_lamp2_w
***************************************************************************/
WRITE8_HANDLER( subs_lamp2_w )
{
set_led_status(1,~offset & 1);
}
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