//
// send byte
//
VOID CpPutByte(__in PCPPORT Port,__in UCHAR Byte)
{
//
// if modem control, make sure DSR, CTS and CD are all set before sending any data.
//
UCHAR msr;
while((Port->Flags & PORT_MODEMCONTROL) && (msr = READ_UCHAR(Port->Address + COM_MSR) & MS_DSRCTSCD) != MS_DSRCTSCD)
{
//
// if no CD, and there's a charactor ready, eat it
//
if((msr & MS_CD) == 0 && (CpReadLsr(Port,0) & COM_DATRDY) == COM_DATRDY)
READ_UCHAR(Port->Address + COM_DAT);
}
//
// wait for port to not be busy
//
while(!(CpReadLsr(Port, COM_OUTRDY) & COM_OUTRDY));
//
// send the byte
//
WRITE_UCHAR(Port->Address + COM_DAT, Byte);
}
//
// fetch a byte
//
ULONG CpGetByte(__in PCPPORT Port,__out PUCHAR Byte,__in BOOLEAN WaitForByte,__in BOOLEAN CheckOnly)
{
//
// check to make sure the CPPORT we were passed has been initialized.
//
if(!Port->Address)
return CP_GET_NODATA;
ULONG LimitCount = WaitForByte ? 204800 : 1;
while(LimitCount)
{
LimitCount -= 1;
//
// check data ready
//
UCHAR lsr = CpReadLsr(Port,COM_DATRDY);
if((lsr & COM_DATRDY) == COM_DATRDY)
{
//
// check for errors
//
if(lsr & (COM_FE | COM_PE | COM_OE))
{
*Byte = 0;
return CP_GET_ERROR;
}
//
// check data ready only
//
if(CheckOnly)
return CP_GET_SUCCESS;
//
// fetch the byte
//
UCHAR value = READ_PORT_UCHAR(Port->Address + COM_DAT);
if(Port->Flags & PORT_MODEMCONTROL)
{
//
// using modem control. if no CD, then skip this byte.
//
if((READ_UCHAR(Port->Address + COM_MSR) & MS_CD) == 0)
continue;
}
*Byte = value & 0xff;
return CP_GET_SUCCESS;
}
}
CpReadLsr(Port,0);
return CP_GET_NODATA;
}
USHORT
NTAPI
CpGetByte(IN PCPPORT Port,
IN PUCHAR Byte,
IN BOOLEAN Wait,
IN BOOLEAN Poll)
{
UCHAR Lsr;
ULONG i;
/* Handle early read-before-init */
if (!Port->Address) return CP_GET_NODATA;
/* If "wait" mode enabled, spin many times, otherwise attempt just once */
i = Wait ? 204800 : 1;
while (i--)
{
/* Read LSR for data ready */
Lsr = CpReadLsr(Port, SERIAL_LSR_DR);
if ((Lsr & SERIAL_LSR_DR) == SERIAL_LSR_DR)
{
/* If an error happened, clear the byte and fail */
if (Lsr & (SERIAL_LSR_FE | SERIAL_LSR_PE))
{
*Byte = 0;
return CP_GET_ERROR;
}
/* If only polling was requested by caller, return now */
if (Poll) return CP_GET_SUCCESS;
/* Otherwise read the byte and return it */
*Byte = READ_PORT_UCHAR(Port->Address + RECEIVE_BUFFER_REGISTER);
/* Handle CD if port is in modem control mode */
if (Port->Flags & CPPORT_FLAG_MODEM_CONTROL)
{
/* Not implemented yet */
DPRINT1("CP: CPPORT_FLAG_MODEM_CONTROL unexpected\n");
}
/* Byte was read */
return CP_GET_SUCCESS;
}
}
/* Reset LSR, no data was found */
CpReadLsr(Port, 0);
return CP_GET_NODATA;
}
VOID
NTAPI
CpPutByte(IN PCPPORT Port,
IN UCHAR Byte)
{
/* Check if port is in modem control to handle CD */
while (Port->Flags & CPPORT_FLAG_MODEM_CONTROL)
{
/* Not implemented yet */
DPRINT1("CP: CPPORT_FLAG_MODEM_CONTROL unexpected\n");
}
/* Wait for LSR to say we can go ahead */
while (!(CpReadLsr(Port, SERIAL_LSR_THRE) & SERIAL_LSR_THRE));
/* Send the byte */
WRITE_PORT_UCHAR(Port->Address + RECEIVE_BUFFER_REGISTER, Byte);
}
VOID
NTAPI
CpPutByte(IN PCPPORT Port,
IN UCHAR Byte)
{
/* Check if port is in modem control to handle CD */
// while (Port->Flags & CPPORT_FLAG_MODEM_CONTROL) // Commented for the moment.
if (Port->Flags & CPPORT_FLAG_MODEM_CONTROL) // To be removed when this becomes implemented.
{
/* Not implemented yet */
// DPRINT1("CP: CPPORT_FLAG_MODEM_CONTROL unexpected\n");
}
/* Wait for LSR to say we can go ahead */
while ((CpReadLsr(Port, SERIAL_LSR_THRE) & SERIAL_LSR_THRE) == 0x00);
/* Send the byte */
WRITE_PORT_UCHAR(Port->Address + TRANSMIT_HOLDING_REGISTER, Byte);
}
