BizHawk/waterbox/vb/input.cpp

/******************************************************************************/
/* Mednafen Virtual Boy Emulation Module                                      */
/******************************************************************************/
/* input.cpp:
**  Copyright (C) 2010-2016 Mednafen Team
**
** 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.,
** 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

#include "vb.h"
#include "input.h"

namespace MDFN_IEN_VB
{
static bool InstantReadHack;

static bool IntPending;

static uint16 PadData;
static uint16 PadLatched;

static uint8 SCR;
static uint16 SDR;

#define SCR_S_ABT_DIS 0x01
#define SCR_SI_STAT 0x02
#define SCR_HW_SI 0x04
#define SCR_SOFT_CLK 0x10

#define SCR_PARA_SI 0x20
#define SCR_K_INT_INH 0x80

static uint32 ReadBitPos;
static int32 ReadCounter;

static v810_timestamp_t last_ts;

void VBINPUT_Init(void)
{
    InstantReadHack = true;
}

void VBINPUT_SetInstantReadHack(bool enabled)
{
    InstantReadHack = enabled;
}

uint8 VBINPUT_Read(v810_timestamp_t &timestamp, uint32 A)
{
    uint8 ret = 0;

    VBINPUT_Update(timestamp);

    //if(((A & 0xFF) == 0x10 || (A & 0xFF) == 0x14))
    // printf("Read %d\n", timestamp);

    //if(((A & 0xFF) == 0x10 || (A & 0xFF) == 0x14) && ReadCounter > 0)
    //{
    // printf("Input port read during hardware transfer: %08x %d\n", A, timestamp);
    //}

    switch (A & 0xFF)
    {
    case 0x10:
        if (InstantReadHack)
            ret = PadData;
        else
            ret = SDR & 0xFF;
        break;

    case 0x14:
        if (InstantReadHack)
            ret = PadData >> 8;
        else
            ret = SDR >> 8;
        break;

    case 0x28:
        ret = SCR | (0x40 | 0x08 | SCR_HW_SI);
        if (ReadCounter > 0)
            ret |= SCR_SI_STAT;
        break;
    }

    // printf("Input Read: %08x %02x\n", A, ret);
    VB_SetEvent(VB_EVENT_INPUT, (ReadCounter > 0) ? (timestamp + ReadCounter) : VB_EVENT_NONONO);

    return (ret);
}

void VBINPUT_Write(v810_timestamp_t &timestamp, uint32 A, uint8 V)
{
    VBINPUT_Update(timestamp);

    //printf("Input write: %d, %08x %02x\n", timestamp, A, V);
    switch (A & 0xFF)
    {
    case 0x28:
        if ((V & SCR_HW_SI) && !(SCR & SCR_S_ABT_DIS) && ReadCounter <= 0)
        {
            //printf("Start Read: %d\n", timestamp);
            PadLatched = PadData;
            ReadBitPos = 0;
            ReadCounter = 640;
        }

        if (V & SCR_S_ABT_DIS)
        {
            ReadCounter = 0;
            ReadBitPos = 0;
        }

        if (V & SCR_K_INT_INH)
        {
            IntPending = false;
            VBIRQ_Assert(VBIRQ_SOURCE_INPUT, IntPending);
        }

        SCR = V & (0x80 | 0x20 | 0x10 | 1);
        break;
    }

    VB_SetEvent(VB_EVENT_INPUT, (ReadCounter > 0) ? (timestamp + ReadCounter) : VB_EVENT_NONONO);
}

void VBINPUT_Frame(const void* ptr)
{
    PadData = (MDFN_de16lsb(ptr) << 2) | 0x2;
}

v810_timestamp_t VBINPUT_Update(const v810_timestamp_t timestamp)
{
    int32 clocks = timestamp - last_ts;

    if (ReadCounter > 0)
    {
        ReadCounter -= clocks;

        while (ReadCounter <= 0)
        {
            SDR &= ~(1 << ReadBitPos);
            SDR |= PadLatched & (1 << ReadBitPos);

            ReadBitPos++;
            if (ReadBitPos < 16)
                ReadCounter += 640;
            else
            {
                //printf("Read End: %d\n", timestamp);
                if (!(SCR & SCR_K_INT_INH))
                {
                    //printf("Input IRQ: %d\n", timestamp);
                    IntPending = true;
                    VBIRQ_Assert(VBIRQ_SOURCE_INPUT, IntPending);
                }
                break;
            }
        }
    }

    last_ts = timestamp;

    return ((ReadCounter > 0) ? (timestamp + ReadCounter) : VB_EVENT_NONONO);
}

void VBINPUT_ResetTS(void)
{
    last_ts = 0;
}

void VBINPUT_Power(void)
{
    last_ts = 0;
    PadData = 0;
    PadLatched = 0;
    SDR = 0;
    SCR = 0;
    ReadBitPos = 0;
    ReadCounter = 0;
    IntPending = false;

    VBIRQ_Assert(VBIRQ_SOURCE_INPUT, 0);
}
}