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AmigActive 10
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AACD 10.iso
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machine
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pacman.c
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C/C++ Source or Header
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1999-12-07
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1KB
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54 lines
/***************************************************************************
machine.c
Functions to emulate general aspects of the machine (RAM, ROM, interrupts,
I/O ports)
***************************************************************************/
#include "driver.h"
static int speedcheat = 0; /* a well known hack allows to make Pac Man run at four times */
/* his usual speed. When we start the emulation, we check if the */
/* hack can be applied, and set this flag accordingly. */
void pacman_init_machine(void)
{
unsigned char *RAM = memory_region(REGION_CPU1);
/* check if the loaded set of ROMs allows the Pac Man speed hack */
if ((RAM[0x180b] == 0xbe && RAM[0x1ffd] == 0x00) ||
(RAM[0x180b] == 0x01 && RAM[0x1ffd] == 0xbd))
speedcheat = 1;
else
speedcheat = 0;
}
int pacman_interrupt(void)
{
unsigned char *RAM = memory_region(REGION_CPU1);
/* speed up cheat */
if (speedcheat)
{
if (readinputport(4) & 1) /* check status of the fake dip switch */
{
/* activate the cheat */
RAM[0x180b] = 0x01;
RAM[0x1ffd] = 0xbd;
}
else
{
/* remove the cheat */
RAM[0x180b] = 0xbe;
RAM[0x1ffd] = 0x00;
}
}
return interrupt();
}