86Box/src/game/joystick_sw_pad.c

/*
 * 86Box    A hypervisor and IBM PC system emulator that specializes in
 *          running old operating systems and software designed for IBM
 *          PC systems and compatibles from 1981 through fairly recent
 *          system designs based on the PCI bus.
 *
 *          This file is part of the 86Box distribution.
 *
 *          Implementation of a Side Winder GamePad.
 *
 * Notes:   - Write to 0x201 starts packet transfer (5*N or 15*N bits)
 *          - Currently alternates between Mode A and Mode B (is there
 *            any way of actually controlling which is used?)
 *          - Windows 9x drivers require Mode B when more than 1 pad
 *            connected
 *          - Packet preceeded by high data (currently 50us), and
 *            followed by low data (currently 160us) - timings are
 *            probably wrong, but good enough for everything I've tried
 *          - Analog inputs are only used to time ID packet request.
 *            If A0 timing out is followed after ~64us by another 0x201
 *            write then an ID packet is triggered
 *          - Sidewinder game pad ID is 'H0003'
 *          - ID is sent in Mode A (1 bit per clock), but data bit 2
 *            must change during ID packet transfer, or Windows 9x
 *            drivers won't use Mode B. I don't know if it oscillates,
 *            mirrors the data transfer, or something else - the drivers
 *            only check that it changes at least 10 times during the
 *            transfer
 *          - Some DOS stuff will write to 0x201 while a packet is
 *            being transferred. This seems to be ignored.
 *
 *
 *
 * Authors: Miran Grca, <mgrca8@gmail.com>
 *          Sarah Walker, <https://pcem-emulator.co.uk/>
 *
 *          Copyright 2016-2018 Miran Grca.
 *          Copyright 2008-2018 Sarah Walker.
 *
 * 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 <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <wchar.h>
#include <86box/86box.h>
#include <86box/device.h>
#include <86box/timer.h>
#include <86box/gameport.h>
#include <86box/joystick_sw_pad.h>
#include <86box/plat_unused.h>

typedef struct sw_data {
    pc_timer_t poll_timer;
    int        poll_left;
    int        poll_clock;
    uint64_t   poll_data;
    int        poll_mode;

    pc_timer_t trigger_timer;
    int        data_mode;
} sw_data;

static void
sw_timer_over(void *priv)
{
    sw_data *sw = (sw_data *) priv;

    sw->poll_clock = !sw->poll_clock;

    if (sw->poll_clock) {
        sw->poll_data >>= (sw->poll_mode ? 3 : 1);
        sw->poll_left--;
    }

    if (sw->poll_left == 1 && !sw->poll_clock)
        timer_advance_u64(&sw->poll_timer, TIMER_USEC * 160);
    else if (sw->poll_left)
        timer_advance_u64(&sw->poll_timer, TIMER_USEC * 5);
    else
        timer_disable(&sw->poll_timer);
}

static void
sw_trigger_timer_over(void *priv)
{
    sw_data *sw = (sw_data *) priv;

    timer_disable(&sw->trigger_timer);
}

static int
sw_parity(uint16_t data)
{
    int bits_set = 0;

    while (data) {
        bits_set++;
        data &= (data - 1);
    }

    return bits_set & 1;
}

static void *
sw_init(void)
{
    sw_data *sw = (sw_data *) malloc(sizeof(sw_data));
    memset(sw, 0, sizeof(sw_data));

    timer_add(&sw->poll_timer, sw_timer_over, sw, 0);
    timer_add(&sw->trigger_timer, sw_trigger_timer_over, sw, 0);

    return sw;
}

static void
sw_close(void *priv)
{
    sw_data *sw = (sw_data *) priv;

    free(sw);
}

static uint8_t
sw_read(void *priv)
{
    sw_data *sw   = (sw_data *) priv;
    uint8_t  temp = 0;

    if (!JOYSTICK_PRESENT(0))
        return 0xff;

    if (timer_is_enabled(&sw->poll_timer)) {
        if (sw->poll_clock)
            temp |= 0x10;

        if (sw->poll_mode)
            temp |= (sw->poll_data & 7) << 5;
        else {
            temp |= ((sw->poll_data & 1) << 5) | 0xc0;
            if (sw->poll_left > 31 && !(sw->poll_left & 1))
                temp &= ~0x80;
        }
    } else
        temp |= 0xf0;

    return temp;
}

static void
sw_write(void *priv)
{
    sw_data *sw              = (sw_data *) priv;
    int64_t  time_since_last = timer_get_remaining_us(&sw->trigger_timer);

    if (!JOYSTICK_PRESENT(0))
        return;

    timer_process();

    if (!sw->poll_left) {
        sw->poll_clock = 1;
        timer_set_delay_u64(&sw->poll_timer, TIMER_USEC * 50);

        if (time_since_last > 9900 && time_since_last < 9940) {
            sw->poll_mode = 0;
            sw->poll_left = 49;
            sw->poll_data = 0x2400ULL | (0x1830ULL << 15) | (0x19b0ULL << 30);
        } else {
            sw->poll_mode = sw->data_mode;
            sw->data_mode = !sw->data_mode;

            if (sw->poll_mode) {
                sw->poll_left = 1;
                sw->poll_data = 7;
            } else {
                sw->poll_left = 1;
                sw->poll_data = 1;
            }

            for (uint8_t c = 0; c < 4; c++) {
                uint16_t data = 0x3fff;

                if (!JOYSTICK_PRESENT(c))
                    break;

                if (joystick_state[c].axis[1] < -16383)
                    data &= ~1;
                if (joystick_state[c].axis[1] > 16383)
                    data &= ~2;
                if (joystick_state[c].axis[0] > 16383)
                    data &= ~4;
                if (joystick_state[c].axis[0] < -16383)
                    data &= ~8;

                for (uint8_t b = 0; b < 10; b++) {
                    if (joystick_state[c].button[b])
                        data &= ~(1 << (b + 4));
                }

                if (sw_parity(data))
                    data |= 0x4000;

                if (sw->poll_mode) {
                    sw->poll_left += 5;
                    sw->poll_data |= (data << (c * 15 + 3));
                } else {
                    sw->poll_left += 15;
                    sw->poll_data |= (data << (c * 15 + 1));
                }
            }
        }
    }

    timer_disable(&sw->trigger_timer);
}

static int
sw_read_axis(UNUSED(void *priv), UNUSED(int axis))
{
    if (!JOYSTICK_PRESENT(0))
        return AXIS_NOT_PRESENT;

    return 0; /*No analogue support on Sidewinder game pad*/
}

static void
sw_a0_over(void *priv)
{
    sw_data *sw = (sw_data *) priv;

    timer_set_delay_u64(&sw->trigger_timer, TIMER_USEC * 10000);
}

const joystick_if_t joystick_sw_pad = {
    .name          = "Microsoft SideWinder Pad",
    .internal_name = "sidewinder_pad",
    .init          = sw_init,
    .close         = sw_close,
    .read          = sw_read,
    .write         = sw_write,
    .read_axis     = sw_read_axis,
    .a0_over       = sw_a0_over,
    .axis_count    = 2,
    .button_count  = 10,
    .pov_count     = 0,
    .max_joysticks = 4,
    .axis_names    = { "X axis", "Y axis" },
    .button_names  = { "A", "B", "C", "X", "Y", "Z", "L", "R", "Start", "M" },
    .pov_names     = { NULL }
};