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https://github.com/ekeeke/Genesis-Plus-GX.git
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120 lines
3.8 KiB
C
120 lines
3.8 KiB
C
/***************************************************************************************
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* Genesis Plus
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* Sega Paddle Control support
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*
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* Copyright (C) 2007-2023 Eke-Eke (Genesis Plus GX)
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*
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* Redistribution and use of this code or any derivative works are permitted
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* provided that the following conditions are met:
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*
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* - Redistributions may not be sold, nor may they be used in a commercial
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* product or activity.
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*
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* - Redistributions that are modified from the original source must include the
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* complete source code, including the source code for all components used by a
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* binary built from the modified sources. However, as a special exception, the
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* source code distributed need not include anything that is normally distributed
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* (in either source or binary form) with the major components (compiler, kernel,
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* and so on) of the operating system on which the executable runs, unless that
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* component itself accompanies the executable.
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*
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* - Redistributions must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************************/
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#include "shared.h"
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static struct
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{
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uint8 State;
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uint8 Counter;
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} paddle[2];
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void paddle_reset(int port)
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{
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input.analog[port][0] = 128;
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paddle[port>>2].State = 0x40;
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paddle[port>>2].Counter = 0;
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}
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INLINE unsigned char paddle_read(int port)
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{
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/* FIRE button status (active low) */
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unsigned char temp = ~(input.pad[port] & 0x10);
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/* Pad index */
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int index = port >> 2;
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/* Clear low bits */
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temp &= 0x70;
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/* Japanese model: automatic flip-flop */
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if (region_code < REGION_USA)
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{
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/* two I/O port reads are required to fully read paddles state on control ports 1 & 2 so using two read access latency for switching should be safe */
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/* note: real paddle switching time is approx. 62.5 us period according to https://www.raphnet.net/electronique/sms_paddle/index_en.php#4 */
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if (++paddle[index].Counter > 2)
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{
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paddle[index].Counter = 0;
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paddle[index].State ^= 0x40;
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}
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}
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if (paddle[index].State & 0x40)
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{
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/* return higher bits */
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temp |= (input.analog[port][0] >> 4) & 0x0F;
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}
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else
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{
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/* return lower bits */
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temp |= input.analog[port][0] & 0x0F;
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/* set TR low */
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temp &= ~0x20;
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}
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return temp;
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}
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INLINE void paddle_write(int index, unsigned char data, unsigned char mask)
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{
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/* update bits set as output only */
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paddle[index].State = (paddle[index].State & ~mask) | (data & mask);
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}
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unsigned char paddle_1_read(void)
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{
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return paddle_read(0);
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}
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unsigned char paddle_2_read(void)
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{
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return paddle_read(4);
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}
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void paddle_1_write(unsigned char data, unsigned char mask)
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{
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paddle_write(0, data, mask);
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}
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void paddle_2_write(unsigned char data, unsigned char mask)
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{
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paddle_write(1, data, mask);
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}
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