/***************************************************************************
*
*    fm.c
*
*    Copyright (c) 1991-1996 Microsoft Corporation.  All Rights Reserved.
*
*    This code provides VDD support for SB 2.0 sound output, specifically:
*        FM Chip OPL2 (a.k.a. Adlib)
*
***************************************************************************/


/*****************************************************************************
*
*    #includes
*
*****************************************************************************/

#include <windows.h>              // The VDD is a win32 DLL
#include <mmsystem.h>             // Multi-media APIs
#include <vddsvc.h>               // Definition of VDD calls
#include <vsb.h>
#include <fm.h>


/*****************************************************************************
*
*    Globals
*
*****************************************************************************/

HANDLE HFM = NULL; // current open FM device
BOOL FMActive = FALSE; // indicates whether we have an FM device
BYTE AdlibRegister = 0x00; // register currently selected
int Position = 0; // position in PortData array
SYNTH_DATA PortData[BATCH_SIZE]; // batched data to be written to OPL2 device
BOOL Timer1Started = FALSE; // if a timer interrupts then it's stopped
BOOL Timer2Started = FALSE; // if a timer interrupts then it's stopped
BYTE Status = 0x06; // or 0x00, see sb programming book page xi


/****************************************************************************
*
*    FM device routines
*
****************************************************************************/

VOID
ResetFM(
    VOID
    )
{
    AdlibRegister = 0x00; // register currently selected
    Position = 0;
    Timer1Started = FALSE;
    Timer2Started = FALSE;
    Status = 0x06;
}

VOID
FMStatusRead(
    BYTE *data
    )
{
#if 0 // This should work but doesn't (ReadFile fails)
        // Are we expecting a state change ?

        if (Timer1Started || Timer2Started) {
             // Read the status port from the driver - this is how the
             // driver interprets read.
             // Well, actually don't because the WSS driver doesn't work!

            if (!ReadFile(HFM, &Status, 1, &bytesRead, NULL)) {
#if DBG
                FormatMessageA( FORMAT_MESSAGE_ALLOCATE_BUFFER |
                  FORMAT_MESSAGE_FROM_SYSTEM,
                  NULL, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                  (char *) &lpMsgBuf, 0, NULL);
                dprintf1(("FM read port failed: %d bytes of data read, error message: %s",
                            bytesRead, lpMsgBuf));
                LocalFree( lpMsgBuf ); // Free the buffer.
#endif DBG
                break;
            }
            else {
                 // Look for state change

                if (Status & 0x40) {
                     Timer1Started = FALSE;
                     dprintf2(("Timer 1 finished"));
            }

                if (Status & 0x20) {
                    Timer2Started = FALSE;
                    dprintf2(("Timer 2 finished"));
            }
            }
        }
#endif
        *data = Status;
}

VOID
FMRegisterSelect(
    BYTE data
    )
{
    AdlibRegister = data;
}

VOID
FMDataWrite(
    BYTE data
    )
{
    if(AdlibRegister==AD_NEW) {
        data &=0xFE; // don't enter opl3 mode
    }

    // put data in PortData array
    if(Position <= BATCH_SIZE-2) {
        PortData[Position].IoPort = ADLIB_REGISTER_SELECT_PORT;
        PortData[Position].PortData = AdlibRegister;
        PortData[Position + 1].IoPort = ADLIB_DATA_PORT;
        PortData[Position + 1].PortData = data;
        Position += 2;
    } else {
        dprintf1(("Attempting to write beyond end of PortData array"));
    }

    if (Position == BATCH_SIZE ||
        AdlibRegister>=0xB0 && AdlibRegister<=0xBD ||
        AdlibRegister == AD_MASK) {
        // PortData full or note-on/off command or changing status
        if (!FMPortWrite()) {
            dprintf1(("Failed to write to device!"));
        } else {
            // Work out what status change may have occurred
            if (AdlibRegister == AD_MASK) {
                // Look for RST and starting timers
                if (data & 0x80) {
                    Status = 0x00; // reset both timers
            }

                // We ignore starting of timers if their interrupt
                // flag is set because the timer status will have to
                // be set again to make the status for this timer change

                if ((data & 1) && !(Status & 0x40)) {
                    dprintf2(("Timer 1 started"));
#if 0
                    Timer1Started = TRUE;
#else
                    Status |= 0xC0; // simulate immediate expiry of timer1
#endif
                } else {
                    Timer1Started = FALSE;
                }

                if ((data & 2) && !(Status & 0x20)) {
                    dprintf2(("Timer 2 started"));
#if 0
                    Timer2Started = TRUE;
#else
                    Status |= 0xA0; // simulate immediate expiry of timer2
#endif
                    Timer2Started = TRUE;
                } else {
                    Timer2Started = FALSE;
                }
           }
        }
    }
}

/*
*    Opens opl2 device adlib.mid or adlib.mid0 as a file handle.
*    Returns TRUE on success.
*/

BOOL
OpenFMDevice(
    VOID
    )
{
    DWORD dwBytesReturned;
    LPVOID lpMsgBuf;

    // attempt to open device file adlib.mid or adlib.mid0
    HFM = CreateFile(L"\\\\.\\adlib.mid", GENERIC_READ | GENERIC_WRITE,
      FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
    if (HFM == INVALID_HANDLE_VALUE) {
        HFM = CreateFile(L"\\\\.\\adlib.mid0", GENERIC_READ | GENERIC_WRITE,
          FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
    }

    if (HFM == INVALID_HANDLE_VALUE) {
#if DBG
        FormatMessageA( FORMAT_MESSAGE_ALLOCATE_BUFFER |
          FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
          MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (char *) &lpMsgBuf, 0, NULL);
        dprintf1(("Create FM out failed, error message: %s", lpMsgBuf));
        LocalFree( lpMsgBuf ); // Free the buffer.
#endif // DBG
        return FALSE;
    }
    FMActive = TRUE;
    return TRUE;
}

/***************************************************************************/

/*
*    Closes our FM device.
*/

VOID
CloseFMDevice(
    VOID
    )
{
    dprintf2(("Closing FM device"));

    if (HFM) {
        CloseHandle(HFM);
        HFM = NULL;
        FMActive = FALSE;
    }
}

/***************************************************************************/

/*
*    Sends FM data to the card.
*    Returns TRUE on success.
*/

BOOL
FMPortWrite(
    VOID
    )
{
    DWORD bytesWritten = 0;
    LPVOID lpMsgBuf;

    if(FMActive) {
        dprintf4(("Writing %d bytes of data to port",
          Position * sizeof(PortData[0])));
        if(!WriteFile(HFM, &PortData, Position * sizeof(PortData[0]),
          &bytesWritten, NULL)) {
#if DBG
            FormatMessageA( FORMAT_MESSAGE_ALLOCATE_BUFFER |
              FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
              MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (char *) &lpMsgBuf,
                0, NULL);

            dprintf1(("FM write failed: %d bytes of data written, error message: %s",
              bytesWritten, lpMsgBuf));
            LocalFree( lpMsgBuf ); // Free the buffer.
#endif //DBG
             return FALSE;
        }
    }
    Position = 0;
    return TRUE;
}

/***************************************************************************/