VOID
SerialHandleReducedIntBuffer(
IN PSERIAL_DEVICE_EXTENSION Extension
)
/*++
Routine Description:
This routine is called to handle a reduction in the number
of characters in the interrupt (typeahead) buffer. It
will check the current output flow control and re-enable transmission
as needed.
NOTE: This routine assumes that it is working at interrupt level.
Arguments:
Extension - A pointer to the device extension.
Return Value:
None.
--*/
{
//
// If we are doing receive side flow control and we are
// currently "holding" then because we've emptied out
// some characters from the interrupt buffer we need to
// see if we can "re-enable" reception.
//
if (Extension->RXHolding) {
if (Extension->CharsInInterruptBuffer <=
(ULONG)Extension->HandFlow.XonLimit) {
if (Extension->RXHolding & SERIAL_RX_DTR) {
Extension->RXHolding &= ~SERIAL_RX_DTR;
SerialSetDTR(Extension);
}
if (Extension->RXHolding & SERIAL_RX_RTS) {
Extension->RXHolding &= ~SERIAL_RX_RTS;
SerialSetRTS(Extension);
}
if (Extension->RXHolding & SERIAL_RX_XOFF) {
//
// Prod the transmit code to send xon.
//
SerialProdXonXoff(
Extension,
TRUE
);
}
}
}
}
BOOLEAN
SerialSetupNewHandFlow(
IN PSERIAL_DEVICE_EXTENSION Extension,
IN PSERIAL_HANDFLOW NewHandFlow
)
/*++
Routine Description:
This routine adjusts the flow control based on new
control flow.
Arguments:
Extension - A pointer to the serial device extension.
NewHandFlow - A pointer to a serial handflow structure
that is to become the new setup for flow
control.
Return Value:
This routine always returns FALSE.
--*/
{
SERIAL_HANDFLOW New = *NewHandFlow;
//
// If the Extension->DeviceIsOpened is FALSE that means
// we are entering this routine in response to an open request.
// If that is so, then we always proceed with the work regardless
// of whether things have changed.
//
//
// First we take care of the DTR flow control. We only
// do work if something has changed.
//
if ((!Extension->DeviceIsOpened) ||
((Extension->HandFlow.ControlHandShake & SERIAL_DTR_MASK) !=
(New.ControlHandShake & SERIAL_DTR_MASK))) {
SerialDump(
SERFLOW,
("SERIAL: Processing DTR flow for %x\n",
Extension->Controller)
);
if (New.ControlHandShake & SERIAL_DTR_MASK) {
//
// Well we might want to set DTR.
//
// Before we do, we need to check whether we are doing
// dtr flow control. If we are then we need to check
// if then number of characters in the interrupt buffer
// exceeds the XoffLimit. If it does then we don't
// enable DTR AND we set the RXHolding to record that
// we are holding because of the dtr.
//
if ((New.ControlHandShake & SERIAL_DTR_MASK)
== SERIAL_DTR_HANDSHAKE) {
if ((Extension->BufferSize - New.XoffLimit) >
Extension->CharsInInterruptBuffer) {
//
// However if we are already holding we don't want
// to turn it back on unless we exceed the Xon
// limit.
//
if (Extension->RXHolding & SERIAL_RX_DTR) {
//
// We can assume that its DTR line is already low.
//
if (Extension->CharsInInterruptBuffer >
(ULONG)New.XonLimit) {
SerialDump(
SERFLOW,
("SERIAL: Removing DTR block on reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_DTR;
SerialSetDTR(Extension);
}
} else {
SerialSetDTR(Extension);
}
} else {
SerialDump(
SERFLOW,
("SERIAL: Setting DTR block on reception for %x\n",
Extension->Controller)
);
Extension->RXHolding |= SERIAL_RX_DTR;
SerialClrDTR(Extension);
}
} else {
//
// Note that if we aren't currently doing dtr flow control then
// we MIGHT have been. So even if we aren't currently doing
// DTR flow control, we should still check if RX is holding
// because of DTR. If it is, then we should clear the holding
// of this bit.
//
if (Extension->RXHolding & SERIAL_RX_DTR) {
SerialDump(
SERFLOW,
("SERIAL: Removing dtr block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_DTR;
}
SerialSetDTR(Extension);
}
} else {
//
// The end result here will be that DTR is cleared.
//
// We first need to check whether reception is being held
// up because of previous DTR flow control. If it is then
// we should clear that reason in the RXHolding mask.
//
if (Extension->RXHolding & SERIAL_RX_DTR) {
SerialDump(
SERFLOW,
("SERIAL: removing dtr block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_DTR;
}
SerialClrDTR(Extension);
}
}
//
// Time to take care of the RTS Flow control.
//
// First we only do work if something has changed.
//
if ((!Extension->DeviceIsOpened) ||
((Extension->HandFlow.FlowReplace & SERIAL_RTS_MASK) !=
(New.FlowReplace & SERIAL_RTS_MASK))) {
SerialDump(
SERFLOW,
("SERIAL: Processing RTS flow\n",
Extension->Controller)
);
if ((New.FlowReplace & SERIAL_RTS_MASK) ==
SERIAL_RTS_HANDSHAKE) {
//
// Well we might want to set RTS.
//
// Before we do, we need to check whether we are doing
// rts flow control. If we are then we need to check
// if then number of characters in the interrupt buffer
// exceeds the XoffLimit. If it does then we don't
// enable RTS AND we set the RXHolding to record that
// we are holding because of the rts.
//
if ((Extension->BufferSize - New.XoffLimit) >
Extension->CharsInInterruptBuffer) {
//
// However if we are already holding we don't want
// to turn it back on unless we exceed the Xon
// limit.
//
if (Extension->RXHolding & SERIAL_RX_RTS) {
//
// We can assume that its RTS line is already low.
//
if (Extension->CharsInInterruptBuffer >
(ULONG)New.XonLimit) {
SerialDump(
SERFLOW,
("SERIAL: Removing rts block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_RTS;
SerialSetRTS(Extension);
}
} else {
SerialSetRTS(Extension);
}
} else {
SerialDump(
SERFLOW,
("SERIAL: Setting rts block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding |= SERIAL_RX_RTS;
SerialClrRTS(Extension);
}
} else if ((New.FlowReplace & SERIAL_RTS_MASK) ==
SERIAL_RTS_CONTROL) {
//
// Note that if we aren't currently doing rts flow control then
// we MIGHT have been. So even if we aren't currently doing
// RTS flow control, we should still check if RX is holding
// because of RTS. If it is, then we should clear the holding
// of this bit.
//
if (Extension->RXHolding & SERIAL_RX_RTS) {
SerialDump(
SERFLOW,
("SERIAL: Clearing rts block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_RTS;
}
SerialSetRTS(Extension);
} else if ((New.FlowReplace & SERIAL_RTS_MASK) ==
SERIAL_TRANSMIT_TOGGLE) {
//
// We first need to check whether reception is being held
// up because of previous RTS flow control. If it is then
// we should clear that reason in the RXHolding mask.
//
if (Extension->RXHolding & SERIAL_RX_RTS) {
SerialDump(
SERFLOW,
("SERIAL: TOGGLE Clearing rts block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_RTS;
}
//
// We have to place the rts value into the Extension
// now so that the code that tests whether the
// rts line should be lowered will find that we
// are "still" doing transmit toggling. The code
// for lowering can be invoked later by a timer so
// it has to test whether it still needs to do its
// work.
//
Extension->HandFlow.FlowReplace &= ~SERIAL_RTS_MASK;
Extension->HandFlow.FlowReplace |= SERIAL_TRANSMIT_TOGGLE;
//
// The order of the tests is very important below.
//
// If there is a break then we should turn on the RTS.
//
// If there isn't a break but there are characters in
// the hardware, then turn on the RTS.
//
// If there are writes pending that aren't being held
// up, then turn on the RTS.
//
if ((Extension->TXHolding & SERIAL_TX_BREAK) ||
((SerialProcessLSR(Extension) & (SERIAL_LSR_THRE |
SERIAL_LSR_TEMT)) !=
(SERIAL_LSR_THRE |
SERIAL_LSR_TEMT)) ||
(Extension->CurrentWriteIrp || Extension->TransmitImmediate ||
(!IsListEmpty(&Extension->WriteQueue)) &&
(!Extension->TXHolding))) {
SerialSetRTS(Extension);
} else {
//
// This routine will check to see if it is time
// to lower the RTS because of transmit toggle
// being on. If it is ok to lower it, it will,
// if it isn't ok, it will schedule things so
// that it will get lowered later.
//
Extension->CountOfTryingToLowerRTS++;
SerialPerhapsLowerRTS(Extension);
}
} else {
//
// The end result here will be that RTS is cleared.
//
// We first need to check whether reception is being held
// up because of previous RTS flow control. If it is then
// we should clear that reason in the RXHolding mask.
//
if (Extension->RXHolding & SERIAL_RX_RTS) {
SerialDump(
SERFLOW,
("SERIAL: Clearing rts block of reception for %x\n",
Extension->Controller)
);
Extension->RXHolding &= ~SERIAL_RX_RTS;
}
SerialClrRTS(Extension);
}
}
//
// We now take care of automatic receive flow control.
// We only do work if things have changed.
//
if ((!Extension->DeviceIsOpened) ||
((Extension->HandFlow.FlowReplace & SERIAL_AUTO_RECEIVE) !=
(New.FlowReplace & SERIAL_AUTO_RECEIVE))) {
if (New.FlowReplace & SERIAL_AUTO_RECEIVE) {
//
// We wouldn't be here if it had been on before.
//
// We should check to see whether we exceed the turn
// off limits.
//
// Note that since we are following the OS/2 flow
// control rules we will never send an xon if
// when enabling xon/xoff flow control we discover that
// we could receive characters but we are held up do
// to a previous Xoff.
//
if ((Extension->BufferSize - New.XoffLimit) <=
Extension->CharsInInterruptBuffer) {
//
// Cause the Xoff to be sent.
//
Extension->RXHolding |= SERIAL_RX_XOFF;
SerialProdXonXoff(
Extension,
FALSE
);
}
} else {
//
// The app has disabled automatic receive flow control.
//
// If transmission was being held up because of
// an automatic receive Xoff, then we should
// cause an Xon to be sent.
//
if (Extension->RXHolding & SERIAL_RX_XOFF) {
Extension->RXHolding &= ~SERIAL_RX_XOFF;
//
// Cause the Xon to be sent.
//
SerialProdXonXoff(
Extension,
TRUE
);
}
}
}
//
// We now take care of automatic transmit flow control.
// We only do work if things have changed.
//
if ((!Extension->DeviceIsOpened) ||
((Extension->HandFlow.FlowReplace & SERIAL_AUTO_TRANSMIT) !=
(New.FlowReplace & SERIAL_AUTO_TRANSMIT))) {
if (New.FlowReplace & SERIAL_AUTO_TRANSMIT) {
//
// We wouldn't be here if it had been on before.
//
// BUG BUG ??? There is some belief that if autotransmit
// was just enabled, I should go look in what we
// already received, and if we find the xoff character
// then we should stop transmitting. I think this
// is an application bug. For now we just care about
// what we see in the future.
//
;
} else {
//
// The app has disabled automatic transmit flow control.
//
// If transmission was being held up because of
// an automatic transmit Xoff, then we should
// cause an Xon to be sent.
//
if (Extension->TXHolding & SERIAL_TX_XOFF) {
Extension->TXHolding &= ~SERIAL_TX_XOFF;
//
// Cause the Xon to be sent.
//
SerialProdXonXoff(
Extension,
TRUE
);
}
}
}
//
// At this point we can simply make sure that entire
// handflow structure in the extension is updated.
//
Extension->HandFlow = New;
return FALSE;
}
VOID
SerialPutChar(
IN PSERIAL_DEVICE_EXTENSION Extension,
IN UCHAR CharToPut
)
/*++
Routine Description:
This routine, which only runs at device level, takes care of
placing a character into the typeahead (receive) buffer.
Arguments:
Extension - The serial device extension.
Return Value:
None.
--*/
{
PREQUEST_CONTEXT reqContext = NULL;
//
// If we have dsr sensitivity enabled then
// we need to check the modem status register
// to see if it has changed.
//
if (Extension->HandFlow.ControlHandShake &
SERIAL_DSR_SENSITIVITY) {
SerialHandleModemUpdate(
Extension,
FALSE
);
if (Extension->RXHolding & SERIAL_RX_DSR) {
//
// We simply act as if we haven't
// seen the character if we have dsr
// sensitivity and the dsr line is low.
//
return;
}
}
//
// If the xoff counter is non-zero then decrement it.
// If the counter then goes to zero, complete that request.
//
if (Extension->CountSinceXoff) {
Extension->CountSinceXoff--;
if (!Extension->CountSinceXoff) {
reqContext = SerialGetRequestContext(Extension->CurrentXoffRequest);
reqContext->Status = STATUS_SUCCESS;
reqContext->Information = 0;
SerialInsertQueueDpc(
Extension->XoffCountCompleteDpc
);
}
}
//
// Check to see if we are copying into the
// users buffer or into the interrupt buffer.
//
// If we are copying into the user buffer
// then we know there is always room for one more.
// (We know this because if there wasn't room
// then that read would have completed and we
// would be using the interrupt buffer.)
//
// If we are copying into the interrupt buffer
// then we will need to check if we have enough
// room.
//
if (Extension->ReadBufferBase !=
Extension->InterruptReadBuffer) {
//
// Increment the following value so
// that the interval timer (if one exists
// for this read) can know that a character
// has been read.
//
Extension->ReadByIsr++;
//
// We are in the user buffer. Place the
// character into the buffer. See if the
// read is complete.
//
*Extension->CurrentCharSlot = CharToPut;
if (Extension->CurrentCharSlot ==
Extension->LastCharSlot) {
//
// We've filled up the users buffer.
// Switch back to the interrupt buffer
// and send off a DPC to Complete the read.
//
// It is inherent that when we were using
// a user buffer that the interrupt buffer
// was empty.
//
Extension->ReadBufferBase =
Extension->InterruptReadBuffer;
Extension->CurrentCharSlot =
Extension->InterruptReadBuffer;
Extension->FirstReadableChar =
Extension->InterruptReadBuffer;
Extension->LastCharSlot =
Extension->InterruptReadBuffer +
(Extension->BufferSize - 1);
Extension->CharsInInterruptBuffer = 0;
reqContext = SerialGetRequestContext(Extension->CurrentReadRequest);
reqContext->Information = reqContext->Length;
SerialInsertQueueDpc(
Extension->CompleteReadDpc
);
} else {
//
// Not done with the users read.
//
Extension->CurrentCharSlot++;
}
} else {
//
// We need to see if we reached our flow
// control threshold. If we have then
// we turn on whatever flow control the
// owner has specified. If no flow
// control was specified, well..., we keep
// trying to receive characters and hope that
// we have enough room. Note that no matter
// what flow control protocol we are using, it
// will not prevent us from reading whatever
// characters are available.
//
if ((Extension->HandFlow.ControlHandShake
& SERIAL_DTR_MASK) ==
SERIAL_DTR_HANDSHAKE) {
//
// If we are already doing a
// dtr hold then we don't have
// to do anything else.
//
if (!(Extension->RXHolding &
SERIAL_RX_DTR)) {
if ((Extension->BufferSize -
Extension->HandFlow.XoffLimit)
<= (Extension->CharsInInterruptBuffer+1)) {
Extension->RXHolding |= SERIAL_RX_DTR;
SerialClrDTR(Extension->WdfInterrupt, Extension);
}
}
}
if ((Extension->HandFlow.FlowReplace
& SERIAL_RTS_MASK) ==
SERIAL_RTS_HANDSHAKE) {
//
// If we are already doing a
// rts hold then we don't have
// to do anything else.
//
if (!(Extension->RXHolding &
SERIAL_RX_RTS)) {
if ((Extension->BufferSize -
Extension->HandFlow.XoffLimit)
<= (Extension->CharsInInterruptBuffer+1)) {
Extension->RXHolding |= SERIAL_RX_RTS;
SerialClrRTS(Extension->WdfInterrupt, Extension);
}
}
}
if (Extension->HandFlow.FlowReplace &
SERIAL_AUTO_RECEIVE) {
//
// If we are already doing a
// xoff hold then we don't have
// to do anything else.
//
if (!(Extension->RXHolding &
SERIAL_RX_XOFF)) {
if ((Extension->BufferSize -
Extension->HandFlow.XoffLimit)
<= (Extension->CharsInInterruptBuffer+1)) {
Extension->RXHolding |= SERIAL_RX_XOFF;
//
// If necessary cause an
// off to be sent.
//
SerialProdXonXoff(
Extension,
FALSE
);
}
}
}
if (Extension->CharsInInterruptBuffer <
Extension->BufferSize) {
*Extension->CurrentCharSlot = CharToPut;
Extension->CharsInInterruptBuffer++;
//
// If we've become 80% full on this character
// and this is an interesting event, note it.
//
if (Extension->CharsInInterruptBuffer ==
Extension->BufferSizePt8) {
if (Extension->IsrWaitMask &
SERIAL_EV_RX80FULL) {
Extension->HistoryMask |= SERIAL_EV_RX80FULL;
if (Extension->IrpMaskLocation) {
*Extension->IrpMaskLocation =
Extension->HistoryMask;
Extension->IrpMaskLocation = NULL;
Extension->HistoryMask = 0;
reqContext = SerialGetRequestContext(Extension->CurrentWaitRequest);
reqContext->Information = sizeof(ULONG);
SerialInsertQueueDpc(
Extension->CommWaitDpc
);
}
}
}
//
// Point to the next available space
// for a received character. Make sure
// that we wrap around to the beginning
// of the buffer if this last character
// received was placed at the last slot
// in the buffer.
//
if (Extension->CurrentCharSlot ==
Extension->LastCharSlot) {
Extension->CurrentCharSlot =
Extension->InterruptReadBuffer;
} else {
Extension->CurrentCharSlot++;
}
} else {
//
// We have a new character but no room for it.
//
Extension->PerfStats.BufferOverrunErrorCount++;
Extension->WmiPerfData.BufferOverrunErrorCount++;
Extension->ErrorWord |= SERIAL_ERROR_QUEUEOVERRUN;
if (Extension->HandFlow.FlowReplace &
SERIAL_ERROR_CHAR) {
//
// Place the error character into the last
// valid place for a character. Be careful!,
// that place might not be the previous location!
//
if (Extension->CurrentCharSlot ==
Extension->InterruptReadBuffer) {
*(Extension->InterruptReadBuffer+
(Extension->BufferSize-1)) =
Extension->SpecialChars.ErrorChar;
} else {
*(Extension->CurrentCharSlot-1) =
Extension->SpecialChars.ErrorChar;
}
}
//
// If the application has requested it, abort all reads
// and writes on an error.
//
if (Extension->HandFlow.ControlHandShake &
SERIAL_ERROR_ABORT) {
SerialInsertQueueDpc(
Extension->CommErrorDpc
);
}
}
}
}
