
#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 log_cb(RETRO_LOG_DEBUG, LOGPRE "Unknown protection read.  PC=%04X  Offset=%04X\n", activecpu_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:
				log_cb(RETRO_LOG_DEBUG, LOGPRE "Unemulated protection command=%02X.  PC=%04X\n", protection_command, activecpu_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 log_cb(RETRO_LOG_DEBUG, LOGPRE "Unknown protection write=%02X.  PC=%04X  Offset=%04X\n", data, activecpu_get_pc(), offset);
}
