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/***************************************************************************************
* Genesis Plus
* XE-1AP analog controller support
*
* Copyright (C) 2011-2015 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"
#define XE_1AP_LATENCY 3
static struct
{
uint8 State;
uint8 Counter;
uint8 Latency;
} xe_1ap[2];
void xe_1ap_reset(int index)
{
input.analog[index][0] = 128;
input.analog[index][1] = 128;
input.analog[index+1][0] = 128;
index >>= 2;
xe_1ap[index].State = 0x40;
xe_1ap[index].Counter = 11;
xe_1ap[index].Latency = 0;
}
INLINE unsigned char xe_1ap_read(int index)
{
unsigned char data;
unsigned int port = index << 2;
/* Current data transfer cycle */
switch (xe_1ap[index].Counter)
{
case 0: /* E1 E2 Start Select buttons status (active low) */
data = (~input.pad[port] >> 10) & 0x0F;
break;
case 1: /* A/A' B/B' C D buttons status (active low) */
data = ((~input.pad[port] >> 4) & 0x0F) & ~((input.pad[port] >> 6) & 0x0C);
break;
case 2: /* CH0 high (Analog Stick Left/Right direction) */
data = (input.analog[port][0] >> 4) & 0x0F;
break;
case 3: /* CH1 high (Analog Stick Up/Down direction) */
data = (input.analog[port][1] >> 4) & 0x0F;
break;
case 4: /* CH2 high (N/A) */
data = 0x0;
break;
case 5: /* CH3 high (Throttle vertical or horizontal direction) */
data = (input.analog[port+1][0] >> 4) & 0x0F;
break;
case 6: /* CH0 low (Analog Stick Left/Right direction) */
data = input.analog[port][0] & 0x0F;
break;
case 7: /* CH1 low (Analog Stick Up/Down direction)*/
data = input.analog[port][1] & 0x0F;
break;
case 8: /* CH2 low (N/A) */
data = 0x0;
break;
case 9: /* CH3 low (Throttle vertical or horizontal direction) */
data = input.analog[port+1][0] & 0x0F;
break;
case 10: /* A B A' B' buttons status (active low) */
data = (~input.pad[port] >> 6) & 0x0F;
break;
default: /* N/A */
data = 0x0F;
break;
}
/* TL indicates current data cycle (0=1st cycle, 1=2nd cycle, etc) */
data |= ((xe_1ap[index].Counter & 1) << 4);
/* TR indicates if data is valid (0=valid, 1=not ready) */
/* Some games expect this bit to switch between 0 and 1 */
/* so we actually keep it high for some reads after the */
/* data cycle has been initialized or incremented */
if (xe_1ap[index].Latency)
{
if (xe_1ap[index].Latency > 1)
{
/* data is not ready */
data |= 0x20;
}
/* decrement internal latency */
xe_1ap[index].Latency--;
}
else if (xe_1ap[index].Counter <= 10)
{
/* next data cycle */
xe_1ap[index].Counter++;
/* reinitialize internal latency */
xe_1ap[index].Latency = XE_1AP_LATENCY;
}
return data;
}
INLINE void xe_1ap_write(int index, unsigned char data, unsigned char mask)
{
/* only update bits set as output */
data = (xe_1ap[index].State & ~mask) | (data & mask);
/* look for TH 1->0 transitions */
if (!(data & 0x40) && (xe_1ap[index].State & 0x40))
{
/* reset data acquisition cycle */
xe_1ap[index].Counter = 0;
/* initialize internal latency */
xe_1ap[index].Latency = XE_1AP_LATENCY;
}
/* update internal state */
xe_1ap[index].State = data;
}
unsigned char xe_1ap_1_read(void)
{
return xe_1ap_read(0);
}
unsigned char xe_1ap_2_read(void)
{
return xe_1ap_read(1);
}
void xe_1ap_1_write(unsigned char data, unsigned char mask)
{
xe_1ap_write(0, data, mask);
}
void xe_1ap_2_write(unsigned char data, unsigned char mask)
{
xe_1ap_write(1, data, mask);
}
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