reactos/drivers/multimedia/audio/mpu401_nt4/portio.c

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/*
*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* FILE: services/dd/mpu401/portio.c (see also mpu401.h)
* PURPOSE: MPU-401 MIDI port I/O helper
* PROGRAMMER: Andrew Greenwood
* UPDATE HISTORY:
* Sept 26, 2003: Created
*/
#include <ntddk.h>
#include "mpu401.h"
BOOLEAN WaitToSend(ULONG BasePort)
{
int TimeOut;
DbgPrint("WaitToSend ");
// Check if it's OK to send
for (TimeOut = MPU401_TIMEOUT;
! MPU401_READY_TO_SEND(BasePort) && TimeOut > 0;
TimeOut --);
// If a time-out occurs, we report failure
if (! TimeOut)
{
DbgPrint("FAILED\n");
return FALSE;
}
DbgPrint("SUCCEEDED\n");
return TRUE;
}
BOOLEAN WaitToReceive(ULONG BasePort)
{
int TimeOut;
DbgPrint("WaitToSend ");
// Check if it's OK to receive
for (TimeOut = MPU401_TIMEOUT;
! MPU401_READY_TO_RECEIVE(BasePort) && TimeOut > 0;
TimeOut --);
// If a time-out occurs, we report failure
if (! TimeOut)
{
DbgPrint("FAILED\n");
return FALSE;
}
DbgPrint("SUCCEEDED\n");
return TRUE;
}
BOOLEAN InitUARTMode(ULONG BasePort)
{
ULONG TimeOut;
UCHAR Status = 0;
DbgPrint("InitUARTMode() called\n");
// Check if it's OK to send
if (! WaitToSend(BasePort))
return FALSE;
DbgPrint("Resetting MPU401\n");
// Send an MPU reset:
MPU401_WRITE_COMMAND(BasePort, 0xff);
// Check if it's OK to receive (some cards will ignore the above reset
// command and so will not issue an ACK, so time out is NOT an error)
DbgPrint("Waiting for an ACK\n");
if (WaitToReceive(BasePort))
{
// Check to make sure the reset was acknowledged:
for (TimeOut = MPU401_TIMEOUT;
(Status = (MPU401_READ_DATA(BasePort) & 0xfe) && TimeOut > 0);
TimeOut --);
}
DbgPrint("Entering UART mode\n");
// Now we kick the MPU401 into UART ("dumb") mode
MPU401_WRITE_COMMAND(BasePort, 0x3f);
return TRUE;
}