Genesis-Plus-GX/source/input_hw/teamplayer.c

177 lines
5.3 KiB
C

/***************************************************************************************
* Genesis Plus
* Team Player support
*
* Copyright (C) 2007-2011 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
static struct
{
uint8 State;
uint8 Counter;
uint8 Table[12];
} teamplayer[2];
void teamplayer_init(int port)
{
int i,padnum;
int index = 0;
/* this table determines which gamepad input should be returned during acquisition sequence
index = teamplayer read table index: 0=1st read, 1=2nd read, ...
table = high bits are pad index, low bits are pad input shift: 0=RLDU, 4=SABC, 8=MXYZ
*/
for (i=0; i<4; i++)
{
padnum = (4 * port) + i;
if (input.dev[padnum] == DEVICE_PAD3B)
{
padnum = padnum << 4;
teamplayer[port].Table[index++] = padnum;
teamplayer[port].Table[index++] = padnum | 4;
}
else
{
padnum = padnum << 4;
teamplayer[port].Table[index++] = padnum;
teamplayer[port].Table[index++] = padnum | 4;
teamplayer[port].Table[index++] = padnum | 8;
}
}
}
void teamplayer_reset(int port)
{
teamplayer[port].State = 0x60; /* TH = 1, TR = 1 */
teamplayer[port].Counter = 0;
}
static __inline__ unsigned int teamplayer_read(int port)
{
unsigned int counter = teamplayer[port].Counter;
/* acquisition sequence */
switch (counter)
{
case 0: /* initial state: TH = 1, TR = 1 -> RLDU = 0011 */
{
return 0x73;
}
case 1: /* start request: TH = 0, TR = 1 -> RLDU = 1111 */
{
return 0x3F;
}
case 2:
case 3: /* ack request: TH=0, TR=0/1 -> RLDU = 0000 */
{
/* TL should match TR */
return ((teamplayer[port].State & 0x20) >> 1);
}
case 4:
case 5:
case 6:
case 7: /* PAD type */
{
unsigned int retval = input.dev[(port << 2) + (counter - 4)];
/* TL should match TR */
return (((teamplayer[port].State & 0x20) >> 1) | retval);
}
default: /* PAD status */
{
unsigned int retval = 0x0F;
/* SEGA teamplayer returns successively PAD1 -> PAD2 -> PAD3 -> PAD4 inputs */
unsigned int padnum = teamplayer[port].Table[counter - 8] >> 4;
/* Each PAD inputs is obtained through 2 or 3 sequential reads: RLDU -> SACB -> MXYZ */
retval &= ~(input.pad[padnum] >> (teamplayer[port].Table[counter - 8] & 0x0F));
/* TL should match TR */
return (((teamplayer[port].State & 0x20) >> 1) | retval);
}
}
}
static __inline__ void teamplayer_write(int port, unsigned char data, unsigned char mask)
{
/* update bits set as output only */
unsigned int state = (teamplayer[port].State & ~mask) | (data & mask);
/* TH & TR handshaking */
if ((teamplayer[port].State ^ state) & 0x60)
{
if (state & 0x40)
{
/* TH high -> reset counter */
teamplayer[port].Counter = 0;
}
else
{
/* increment counter */
teamplayer[port].Counter++;
}
/* update internal state */
teamplayer[port].State = state;
}
}
unsigned char teamplayer_1_read(void)
{
return teamplayer_read(0);
}
unsigned char teamplayer_2_read(void)
{
return teamplayer_read(1);
}
void teamplayer_1_write(unsigned char data, unsigned char mask)
{
teamplayer_write(0, data, mask);
}
void teamplayer_2_write(unsigned char data, unsigned char mask)
{
teamplayer_write(1, data, mask);
}