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AmigActive 10
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xevious.c
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C/C++ Source or Header
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2000-04-23
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8KB
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378 lines
/***************************************************************************
machine.c
Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
I/O ports)
***************************************************************************/
#include "driver.h"
#include "vidhrdw/generic.h"
#include "cpu/z80/z80.h"
unsigned char *xevious_sharedram;
static unsigned char interrupt_enable_1,interrupt_enable_2,interrupt_enable_3;
static unsigned char *rom2a;
static unsigned char *rom2b;
static unsigned char *rom2c;
static int xevious_bs[2];
static void *nmi_timer;
WRITE_HANDLER( xevious_halt_w );
/* namco stick number array */
/*
Input bitmap
bit0 = UP KEY
bit1 = RIGHT KEY
bit2 = DOWN KEY
bit3 = LEFT KEY
Output direction
0
7 1
6 8 2
5 3
4
*/
unsigned char namco_key[16] =
/* LDRU,LDR,LDU,LD ,LRU,LR ,LU , L ,DRU,DR ,DU , D ,RU , R , U ,NON */
{ 5 , 5 , 5 , 5 , 7 , 6 , 7 , 6 , 3 , 3 , 4 , 4 , 1 , 2 , 0 , 8 };
void xevious_init_machine(void)
{
rom2a = memory_region(REGION_GFX4);
rom2b = memory_region(REGION_GFX4)+0x1000;
rom2c = memory_region(REGION_GFX4)+0x3000;
nmi_timer = 0;
xevious_halt_w (0, 0);
}
/* emulation for schematic 9B */
WRITE_HANDLER( xevious_bs_w )
{
xevious_bs[offset & 0x01] = data;
}
READ_HANDLER( xevious_bb_r )
{
int adr_2b,adr_2c;
int dat1,dat2;
/* get BS to 12 bit data from 2A,2B */
adr_2b = ((xevious_bs[1]&0x7e)<<6)|((xevious_bs[0]&0xfe)>>1);
if( adr_2b & 1 ){
/* high bits select */
dat1 = ((rom2a[adr_2b>>1]&0xf0)<<4)|rom2b[adr_2b];
}else{
/* low bits select */
dat1 = ((rom2a[adr_2b>>1]&0x0f)<<8)|rom2b[adr_2b];
}
adr_2c = (dat1 & 0x1ff)<<2;
if( offset & 0x01 )
adr_2c += (1<<11); /* signal 4H to A11 */
if( (xevious_bs[0]&1) ^ ((dat1>>10)&1) )
adr_2c |= 1;
if( (xevious_bs[1]&1) ^ ((dat1>>9)&1) )
adr_2c |= 2;
if( offset & 0x01 ){
/* return BB1 */
dat2 = rom2c[adr_2c];
}else{
/* return BB0 */
dat2 =rom2c[adr_2c];
/* swap bit 6 & 7 */
dat2 = (dat2 & 0x3f) | ((dat2 & 0x80) >> 1) | ((dat2 & 0x40) << 1);
/* flip x & y */
dat2 ^= (dat1 >> 4) & 0x40;
dat2 ^= (dat1 >> 2) & 0x80;
}
return dat2;
}
READ_HANDLER( xevious_sharedram_r )
{
return xevious_sharedram[offset];
}
WRITE_HANDLER( xevious_sharedram_w )
{
xevious_sharedram[offset] = data;
}
READ_HANDLER( xevious_dsw_r )
{
int bit0,bit1;
bit0 = (input_port_0_r(0) >> offset) & 1;
bit1 = (input_port_1_r(0) >> offset) & 1;
return bit0 | (bit1 << 1);
}
/***************************************************************************
Emulate the custom IO chip.
***************************************************************************/
static int customio_command;
static int mode,credits;
static int auxcoinpercred,auxcredpercoin;
static int leftcoinpercred,leftcredpercoin;
static int rightcoinpercred,rightcredpercoin;
static unsigned char customio[16];
WRITE_HANDLER( xevious_customio_data_w )
{
customio[offset] = data;
logerror("%04x: custom IO offset %02x data %02x\n",cpu_get_pc(),offset,data);
switch (customio_command)
{
case 0xa1:
if (offset == 0)
{
if (data == 0x05)
mode = 1; /* go into switch mode */
else /* go into credit mode */
{
credits = 0; /* this is a good time to reset the credits counter */
mode = 0;
}
}
else if (offset == 7)
{
auxcoinpercred = customio[1];
auxcredpercoin = customio[2];
leftcoinpercred = customio[3];
leftcredpercoin = customio[4];
rightcoinpercred = customio[5];
rightcredpercoin = customio[6];
}
break;
case 0x68:
if (offset == 6)
{
/* it is not known how the parameters control the explosion. */
/* We just use samples. */
if (memcmp(customio,"\x40\x40\x40\x01\xff\x00\x20",7) == 0)
sample_start (0, 0, 0);
else if (memcmp(customio,"\x30\x40\x00\x02\xdf\x00\x10",7) == 0)
sample_start (0, 1, 0);
}
break;
}
}
READ_HANDLER( xevious_customio_data_r )
{
if (customio_command != 0x71)
logerror("%04x: custom IO read offset %02x\n",cpu_get_pc(),offset);
switch (customio_command)
{
case 0x71: /* read input */
case 0xb1: /* only issued after 0xe1 (go into credit mode) */
if (offset == 0)
{
if (mode) /* switch mode */
{
/* bit 7 is the service switch */
return readinputport(4);
}
else /* credits mode: return number of credits in BCD format */
{
int in;
static int leftcoininserted;
static int rightcoininserted;
static int auxcoininserted;
in = readinputport(4);
/* check if the user inserted a coin */
if (leftcoinpercred > 0)
{
if ((in & 0x10) == 0 && credits < 99)
{
leftcoininserted++;
if (leftcoininserted >= leftcoinpercred)
{
credits += leftcredpercoin;
leftcoininserted = 0;
}
}
if ((in & 0x20) == 0 && credits < 99)
{
rightcoininserted++;
if (rightcoininserted >= rightcoinpercred)
{
credits += rightcredpercoin;
rightcoininserted = 0;
}
}
if ((in & 0x40) == 0 && credits < 99)
{
auxcoininserted++;
if (auxcoininserted >= auxcoinpercred)
{
credits += auxcredpercoin;
auxcoininserted = 0;
}
}
}
else credits = 2;
/* check for 1 player start button */
if ((in & 0x04) == 0)
if (credits >= 1) credits--;
/* check for 2 players start button */
if ((in & 0x08) == 0)
if (credits >= 2) credits -= 2;
return (credits / 10) * 16 + credits % 10;
}
}
else if (offset == 1)
{
int in;
in = readinputport(2); /* player 1 input */
if (mode == 0) /* convert joystick input only when in credits mode */
in = namco_key[in & 0x0f] | (in & 0xf0);
return in;
}
else if (offset == 2)
{
int in;
in = readinputport(3); /* player 2 input */
if (mode == 0) /* convert joystick input only when in credits mode */
in = namco_key[in & 0x0f] | (in & 0xf0);
return in;
}
break;
case 0x74: /* protect data read ? */
if (offset == 3)
{
if (customio[0] == 0x80 || customio[0] == 0x10)
return 0x05; /* 1st check */
else
return 0x95; /* 2nd check */
}
else return 0x00;
break;
}
return -1;
}
READ_HANDLER( xevious_customio_r )
{
return customio_command;
}
void xevious_nmi_generate (int param)
{
cpu_cause_interrupt (0, Z80_NMI_INT);
}
WRITE_HANDLER( xevious_customio_w )
{
if (data != 0x10 && data != 0x71)
logerror("%04x: custom IO command %02x\n",cpu_get_pc(),data);
customio_command = data;
switch (data)
{
case 0x10:
if (nmi_timer) timer_remove (nmi_timer);
nmi_timer = 0;
return; /* nop */
}
nmi_timer = timer_pulse (TIME_IN_USEC (50), 0, xevious_nmi_generate);
}
WRITE_HANDLER( xevious_halt_w )
{
if (data & 1)
{
cpu_set_reset_line(1,CLEAR_LINE);
cpu_set_reset_line(2,CLEAR_LINE);
}
else
{
cpu_set_reset_line(1,ASSERT_LINE);
cpu_set_reset_line(2,ASSERT_LINE);
}
}
WRITE_HANDLER( xevious_interrupt_enable_1_w )
{
interrupt_enable_1 = (data&1);
}
int xevious_interrupt_1(void)
{
if (interrupt_enable_1) return interrupt();
else return ignore_interrupt();
}
WRITE_HANDLER( xevious_interrupt_enable_2_w )
{
interrupt_enable_2 = data & 1;
}
int xevious_interrupt_2(void)
{
if (interrupt_enable_2) return interrupt();
else return ignore_interrupt();
}
WRITE_HANDLER( xevious_interrupt_enable_3_w )
{
interrupt_enable_3 = !(data & 1);
}
int xevious_interrupt_3(void)
{
if (interrupt_enable_3) return nmi_interrupt();
else return ignore_interrupt();
}