mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
synced 2024-09-17 11:54:50 +02:00
144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
/***************************************************************************************
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* Genesis Plus
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* Sega Mouse support
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*
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* Copyright Eke-Eke (2007-2011)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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uint8 Wait;
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uint8 Port;
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} mouse;
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void mouse_reset(int port)
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{
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input.analog[port][0] = 0;
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input.analog[port][1] = 0;
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mouse.State = 0x60;
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mouse.Counter = 0;
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mouse.Wait = 0;
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mouse.Port = port;
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}
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unsigned char mouse_read()
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{
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unsigned int temp = 0x00;
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int x = input.analog[mouse.Port][0];
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int y = input.analog[mouse.Port][1];
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switch (mouse.Counter)
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{
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case 0: /* initial */
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temp = 0x00;
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break;
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case 1: /* xxxx1011 */
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temp = 0x0B;
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break;
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case 2: /* xxxx1111 */
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temp = 0x0F;
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break;
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case 3: /* xxxx1111 */
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temp = 0x0F;
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break;
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case 4: /* Axis sign & overflow (not emulated) bits */
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temp |= (x < 0);
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temp |= (y < 0) << 1;
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/*
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temp |= (abs(x) > 255) << 2;
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temp |= (abs(y) > 255) << 3;
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*/
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break;
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case 5: /* START, A, B, C buttons state (active high) */
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temp = (input.pad[mouse.Port] >> 4) & 0x0F;
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break;
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case 6: /* X Axis MSB */
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temp = (x >> 4) & 0x0F;
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break;
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case 7: /* X Axis LSB */
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temp = (x & 0x0F);
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break;
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case 8: /* Y Axis MSB */
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temp = (y >> 4) & 0x0F;
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break;
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case 9: /* Y Axis LSB */
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temp = (y & 0x0F);
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break;
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}
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/* TL = busy status */
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if (mouse.Wait)
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{
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/* wait before ACK, fix some buggy mouse routine (Cannon Fodder, Shangai 2, Wack World,...) */
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mouse.Wait = 0;
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/* TL = !TR */
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temp |= (~mouse.State & 0x20) >> 1;
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}
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else
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{
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/* TL = TR (data is ready) */
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temp |= (mouse.State & 0x20) >> 1;
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}
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return temp;
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}
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void mouse_write(unsigned char data, unsigned char mask)
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{
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/* update bits set as output only */
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data = (mouse.State & ~mask) | (data & mask);
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/* TH transition */
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if ((mouse.State ^ data) & 0x40)
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{
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/* start (TH=0) or stop (TH=1) acquisition */
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mouse.Counter = 1 - ((data & 0x40) >> 6);
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}
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/* TR transition */
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if ((mouse.State ^ data) & 0x20)
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{
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/* acquisition in progress */
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if ((mouse.Counter > 0) && (mouse.Counter < 10))
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{
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/* increment phase */
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mouse.Counter++;
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}
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/* TL handshake latency */
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mouse.Wait = 1;
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}
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/* update internal state */
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mouse.State = data;
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}
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