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btime.c
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C/C++ Source or Header
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2000-04-23
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3KB
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94 lines
#include "driver.h"
#define BASE 0xb000
static int protection_command;
static int protection_status = 0;
static int protection_value;
static int protection_ret = 0;
READ_HANDLER( mmonkey_protection_r )
{
unsigned char *RAM = memory_region(REGION_CPU1);
int ret = 0;
if (offset == 0x0000) ret = protection_status;
else if (offset == 0x0e00) ret = protection_ret;
else if (offset >= 0x0d00 && offset <= 0x0d02) ret = RAM[BASE+offset]; /* addition result */
else logerror("Unknown protection read. PC=%04X Offset=%04X\n", cpu_get_pc(), offset);
return ret;
}
WRITE_HANDLER( mmonkey_protection_w )
{
unsigned char *RAM = memory_region(REGION_CPU1);
if (offset == 0)
{
/* protection trigger */
if (data == 0)
{
int i,s1,s2,r;
switch (protection_command)
{
case 0: /* score addition */
s1 = ( 1 * (RAM[BASE+0x0d00] & 0x0f)) + ( 10 * (RAM[BASE+0x0d00] >> 4)) +
( 100 * (RAM[BASE+0x0d01] & 0x0f)) + ( 1000 * (RAM[BASE+0x0d01] >> 4)) +
(10000 * (RAM[BASE+0x0d02] & 0x0f)) + (100000 * (RAM[BASE+0x0d02] >> 4));
s2 = ( 1 * (RAM[BASE+0x0d03] & 0x0f)) + ( 10 * (RAM[BASE+0x0d03] >> 4)) +
( 100 * (RAM[BASE+0x0d04] & 0x0f)) + ( 1000 * (RAM[BASE+0x0d04] >> 4)) +
(10000 * (RAM[BASE+0x0d05] & 0x0f)) + (100000 * (RAM[BASE+0x0d05] >> 4));
r = s1 + s2;
RAM[BASE+0x0d00] = (r % 10); r /= 10;
RAM[BASE+0x0d00] |= ((r % 10) << 4); r /= 10;
RAM[BASE+0x0d01] = (r % 10); r /= 10;
RAM[BASE+0x0d01] |= ((r % 10) << 4); r /= 10;
RAM[BASE+0x0d02] = (r % 10); r /= 10;
RAM[BASE+0x0d02] |= ((r % 10) << 4);
break;
case 1: /* decryption */
/* Compute return value by searching the decryption table. */
/* During the search the status should be 2, but we're done */
/* instanteniously in emulation time */
for (i = 0; i < 0x100; i++)
{
if (RAM[BASE+0x0f00+i] == protection_value)
{
protection_ret = i;
break;
}
}
break;
default:
logerror("Unemulated protection command=%02X. PC=%04X\n", protection_command, cpu_get_pc());
break;
}
protection_status = 0;
}
}
else if (offset == 0x0c00) protection_command = data;
else if (offset == 0x0e00) protection_value = data;
else if (offset >= 0x0f00) RAM[BASE+offset] = data; /* decrypt table */
else if (offset >= 0x0d00 && offset <= 0x0d05) RAM[BASE+offset] = data; /* source table */
else logerror("Unknown protection write=%02X. PC=%04X Offset=%04X\n", data, cpu_get_pc(), offset);
}