blob: 92307ed20e7e0cc432a37a08308b95f71a980c7f (
plain) (
tree)
|
|
/***************************************************************************
machine.c
Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
I/O ports)
***************************************************************************/
#include "driver.h"
static UINT8 from_mcu;
static int mcu_sent = 0,main_sent = 0;
static UINT8 portA_in,portA_out,ddrA;
static UINT8 portB_in,portB_out,ddrB;
static UINT8 portC_in,portC_out,ddrC;
READ8_HANDLER( bigevglf_68705_portA_r )
{
return (portA_out & ddrA) | (portA_in & ~ddrA);
}
WRITE8_HANDLER( bigevglf_68705_portA_w )
{
portA_out = data;
}
WRITE8_HANDLER( bigevglf_68705_ddrA_w )
{
ddrA = data;
}
READ8_HANDLER( bigevglf_68705_portB_r )
{
return (portB_out & ddrB) | (portB_in & ~ddrB);
}
WRITE8_HANDLER( bigevglf_68705_portB_w )
{
if ((ddrB & 0x02) && (~portB_out & 0x02) && (data & 0x02)) /* positive going transition of the clock */
{
cpunum_set_input_line(3,0,CLEAR_LINE);
main_sent = 0;
}
if ((ddrB & 0x04) && (~portB_out & 0x04) && (data & 0x04) ) /* positive going transition of the clock */
{
from_mcu = portA_out;
mcu_sent = 0;
}
portB_out = data;
}
WRITE8_HANDLER( bigevglf_68705_ddrB_w )
{
ddrB = data;
}
READ8_HANDLER( bigevglf_68705_portC_r )
{
portC_in = 0;
if (main_sent) portC_in |= 0x01;
if (mcu_sent) portC_in |= 0x02;
return (portC_out & ddrC) | (portC_in & ~ddrC);
}
WRITE8_HANDLER( bigevglf_68705_portC_w )
{
portC_out = data;
}
WRITE8_HANDLER( bigevglf_68705_ddrC_w )
{
ddrC = data;
}
WRITE8_HANDLER( bigevglf_mcu_w )
{
portA_in = data;
main_sent = 1;
cpunum_set_input_line(3,0,ASSERT_LINE);
}
READ8_HANDLER( bigevglf_mcu_r )
{
mcu_sent = 1;
return from_mcu;
}
READ8_HANDLER( bigevglf_mcu_status_r )
{
int res = 0;
if (!main_sent) res |= 0x08;
if (!mcu_sent) res |= 0x10;
return res;
}
|