Genesis-Plus-GX/source/gen_io.c
ekeeke31 b758b0b57e improved I/O emulation accuracy
optimized gamepad/teamplayer code
2010-07-16 08:30:25 +00:00

205 lines
5.3 KiB
C

/***************************************************************************************
* Genesis Plus
* I/O Chip
*
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
* Eke-Eke (2007,2008,2009), additional code & fixes for the GCN/Wii port
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
****************************************************************************************/
#include "shared.h"
uint8 io_reg[0x10];
uint8 region_code = REGION_USA;
static struct port_t
{
void (*data_w)(unsigned int data);
unsigned int (*data_r)(void);
} port[3];
static void dummy_write(unsigned int data)
{
}
static unsigned int dummy_read(void)
{
return 0x7F;
}
/*****************************************************************************
* I/O chip functions *
* *
*****************************************************************************/
void io_init(void)
{
/* Initialize IO Ports handlers */
switch (input.system[0])
{
case SYSTEM_GAMEPAD:
port[0].data_w = gamepad_1_write;
port[0].data_r = gamepad_1_read;
break;
case SYSTEM_MOUSE:
port[0].data_w = mouse_write;
port[0].data_r = mouse_read;
break;
case SYSTEM_WAYPLAY:
port[0].data_w = wayplay_1_write;
port[0].data_r = wayplay_1_read;
break;
case SYSTEM_TEAMPLAYER:
port[0].data_w = teamplayer_1_write;
port[0].data_r = teamplayer_1_read;
break;
default:
port[0].data_w = dummy_write;
port[0].data_r = dummy_read;
break;
}
switch (input.system[1])
{
case SYSTEM_GAMEPAD:
port[1].data_w = gamepad_2_write;
port[1].data_r = gamepad_2_read;
break;
case SYSTEM_MOUSE:
port[1].data_w = mouse_write;
port[1].data_r = mouse_read;
break;
case SYSTEM_MENACER:
port[1].data_w = dummy_write;
port[1].data_r = menacer_read;
break;
case SYSTEM_JUSTIFIER:
port[1].data_w = dummy_write;
port[1].data_r = justifier_read;
break;
case SYSTEM_WAYPLAY:
port[1].data_w = wayplay_2_write;
port[1].data_r = wayplay_2_read;
break;
case SYSTEM_TEAMPLAYER:
port[1].data_w = teamplayer_2_write;
port[1].data_r = teamplayer_2_read;
break;
default:
port[1].data_w = dummy_write;
port[1].data_r = dummy_read;
break;
}
/* External Port (unconnected) */
port[2].data_w = dummy_write;
port[2].data_r = dummy_read;
/* Initialize connected input devices */
input_init();
}
void io_reset(void)
{
/* Reset I/O registers */
io_reg[0x00] = region_code | 0x20 | (config.tmss & 1);
io_reg[0x01] = 0x00;
io_reg[0x02] = 0x00;
io_reg[0x03] = 0x00;
io_reg[0x04] = 0x00;
io_reg[0x05] = 0x00;
io_reg[0x06] = 0x00;
io_reg[0x07] = 0xFF;
io_reg[0x08] = 0x00;
io_reg[0x09] = 0x00;
io_reg[0x0A] = 0xFF;
io_reg[0x0B] = 0x00;
io_reg[0x0C] = 0x00;
io_reg[0x0D] = 0xFB;
io_reg[0x0E] = 0x00;
io_reg[0x0F] = 0x00;
/* Reset connected input devices */
input_reset();
}
void io_write(unsigned int offset, unsigned int data)
{
switch (offset)
{
case 0x01: /* Port A Data */
case 0x02: /* Port B Data */
case 0x03: /* Port C Data */
io_reg[offset] = data;
port[offset-1].data_w(data);
return;
case 0x04: /* Port A Ctrl */
case 0x05: /* Port B Ctrl */
case 0x06: /* Port C Ctrl */
if (data != io_reg[offset])
{
io_reg[offset] = data;
port[offset-4].data_w(io_reg[offset-3]);
}
return;
case 0x07: /* Port A TxData */
case 0x0A: /* Port B TxData */
case 0x0D: /* Port C TxData */
io_reg[offset] = data;
return;
case 0x09: /* Port A S-Ctrl */
case 0x0C: /* Port B S-Ctrl */
case 0x0F: /* Port C S-Ctrl */
io_reg[offset] = data & 0xF8;
return;
default: /* Read-only ports */
return;
}
}
unsigned int io_read(unsigned int offset)
{
switch(offset)
{
case 0x01: /* Port A Data */
case 0x02: /* Port B Data */
case 0x03: /* Port C Data */
{
unsigned int mask = 0x80 | io_reg[offset + 3];
unsigned int data = port[offset-1].data_r();
return (io_reg[offset] & mask) | (data & ~mask);
}
default: /* return register value */
return io_reg[offset];
}
}