Aiken Harris
d7552f1dce
The static local variable RingFlag in HlComPortReadLsr caused shared state across multiple calls and ports, leading to race conditions and incorrect behavior.
290 lines
7.9 KiB
C
290 lines
7.9 KiB
C
/**
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* PROJECT: ExectOS
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* COPYRIGHT: See COPYING.md in the top level directory
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* FILE: xtoskrnl/hl/cport.c
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* DESCRIPTION: Serial (COM) port support
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* DEVELOPERS: Rafal Kupiec <belliash@codingworkshop.eu.org>
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*/
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#include <xtos.h>
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/**
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* This routine gets a byte from serial port.
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*
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* @param Port
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* Address of port object describing a port settings.
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*
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* @param Byte
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* Address of variable where to store the result.
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*
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* @param Wait
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* Specifies whether to wait for a data or not.
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*
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* @param Poll
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* Indicates whether to only poll, not reading the data.
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*
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* @return This routine returns a status code.
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*
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* @since XT 1.0
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*/
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XTCDECL
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XTSTATUS
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HlComPortGetByte(IN PCPPORT Port,
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OUT PUCHAR Byte,
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IN BOOLEAN Wait,
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IN BOOLEAN Poll)
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{
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UCHAR Lsr;
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ULONG Retry;
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/* Make sure the port has been initialized */
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if(Port->Address == 0)
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{
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return STATUS_DEVICE_NOT_READY;
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}
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/* Retry getting data if allowed to wait */
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Retry = Wait ? COMPORT_WAIT_TIMEOUT : 1;
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while(Retry--)
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{
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/* Get LSR for data ready */
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Lsr = HlComPortReadLsr(Port, COMPORT_LSR_DR);
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if((Lsr & COMPORT_LSR_DR) == COMPORT_LSR_DR)
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{
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/* Check for errors */
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if(Lsr & (COMPORT_LSR_FE | COMPORT_LSR_OE | COMPORT_LSR_PE))
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{
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/* Framing, parity or overrun error occurred */
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*Byte = 0;
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return STATUS_IO_DEVICE_ERROR;
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}
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/* Check if only polling */
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if(Poll)
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{
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/* Only polling, return success */
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return STATUS_SUCCESS;
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}
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/* Read the byte from serial port */
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*Byte = HlIoPortInByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_RBR));
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/* Check if in modem control mode */
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if(Port->Flags & COMPORT_FLAG_MC)
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{
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/* Handle Carrier Detected (CD) */
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if((HlIoPortInByte(PtrToShort(Port->Address + (ULONG)COMPORT_REG_MSR)) & COMPORT_MSR_DCD) == 0)
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{
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/* Skip byte if no CD present */
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continue;
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}
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}
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return STATUS_SUCCESS;
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}
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}
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/* Reset LSR and return that no data found */
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HlComPortReadLsr(Port, 0);
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return STATUS_NOT_FOUND;
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}
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/**
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* This routine writes a byte to the serial port.
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*
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* @param Port
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* Address of port object describing a port settings.
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*
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* @param Byte
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* Data to be written.
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*
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* @return This routine returns a status code.
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*
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* @since XT 1.0
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*/
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XTCDECL
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XTSTATUS
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HlComPortPutByte(IN PCPPORT Port,
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IN UCHAR Byte)
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{
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UCHAR Lsr, Msr;
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/* Make sure the port has been initialized */
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if(Port->Address == 0)
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{
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return STATUS_DEVICE_NOT_READY;
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}
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/* Check if port is in modem control */
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while(Port->Flags & COMPORT_FLAG_MC)
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{
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/* Get the Modem Status Register (MSR) */
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Msr = HlIoPortInByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_MSR)) & COMPORT_MSR_DSRCTSCD;
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if(Msr != COMPORT_MSR_DSRCTSCD)
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{
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/* Take character, if CD is not set */
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Lsr = HlComPortReadLsr(Port, 0);
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if((Msr & COMPORT_MSR_DCD) == 0 && (Lsr & COMPORT_LSR_DR) == COMPORT_LSR_DR)
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{
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/* Eat the character */
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HlIoPortInByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_RBR));
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}
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}
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else
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{
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/* CD, CTS and DSR are set, we can continue */
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break;
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}
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}
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/* Wait for busy port */
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while((HlComPortReadLsr(Port, COMPORT_LSR_THRE) & COMPORT_LSR_THRE) == 0);
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/* Send byte to the port */
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HlIoPortOutByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_THR), Byte);
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return STATUS_SUCCESS;
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}
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/**
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* Reads LSR from specified serial port.
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*
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* @param Port
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* Address of COM port.
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*
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* @param Byte
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* Value expected from the port.
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*
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* @return Byte read from COM port.
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*
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* @since XT 1.0
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*/
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XTCDECL
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UCHAR
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HlComPortReadLsr(IN PCPPORT Port,
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IN UCHAR Byte)
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{
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UCHAR Lsr, Msr;
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/* Read the Line Status Register (LSR) */
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Lsr = HlIoPortInByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_LSR));
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/* Check if expected byte is present */
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if((Lsr & Byte) == 0)
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{
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/* Check Modem Status Register (MSR) for ring indicator */
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Msr = HlIoPortInByte(PtrToUshort(Port->Address + (ULONG)COMPORT_REG_MSR));
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Port->Ring |= (Msr & COMPORT_MSR_RI) ? 1 : 2;
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if(Port->Ring == 3)
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{
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/* Ring indicator toggled, use modem control */
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Port->Flags |= COMPORT_FLAG_MC;
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}
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}
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/* Return byte read */
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return Lsr;
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}
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/**
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* This routine initializes the COM port.
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*
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* @param Port
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* Address of port object describing a port settings.
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*
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* @param PortNumber
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* Supplies a port number.
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*
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* @param PortAddress
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* Supplies an address of the COM port.
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*
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* @param BaudRate
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* Supplies an optional port baud rate.
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*
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* @return This routine returns a status code.
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*
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* @since XT 1.0
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*/
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XTCDECL
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XTSTATUS
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HlInitializeComPort(IN OUT PCPPORT Port,
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IN PUCHAR PortAddress,
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IN ULONG BaudRate)
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{
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USHORT Flags;
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UCHAR Byte;
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ULONG Mode;
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/* Initialize variables */
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Byte = 0;
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Flags = 0;
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/* Check if baud rate is set */
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if(BaudRate == 0)
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{
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/* Use default baud (clock) rate if not set */
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BaudRate = COMPORT_CLOCK_RATE;
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Flags |= COMPORT_FLAG_DBR;
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}
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/* Check whether this port is not already initialized */
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if((Port->Address == PortAddress) && (Port->Baud == BaudRate))
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{
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return STATUS_SUCCESS;
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}
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/* Test if chosen COM port exists */
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do
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{
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/* Check whether the 16450/16550 scratch register exists */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_SR), Byte);
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if(HlIoPortInByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_SR)) != Byte)
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{
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return STATUS_NOT_FOUND;
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}
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}
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while(++Byte != 0);
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/* Disable interrupts */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_LCR), COMPORT_LSR_DIS);
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_IER), COMPORT_LSR_DIS);
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/* Enable Divisor Latch Access Bit (DLAB) */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_LCR), COMPORT_LCR_DLAB);
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/* Set baud rate */
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Mode = COMPORT_CLOCK_RATE / BaudRate;
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_DIV_DLL), (UCHAR)(Mode & 0xFF));
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_DIV_DLM), (UCHAR)((Mode >> 8) & 0xFF));
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/* Set 8 data bits, 1 stop bits, no parity (8n1) */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_LCR),
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COMPORT_LCR_8DATA | COMPORT_LCR_1STOP | COMPORT_LCR_PARN);
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/* Enable DTR, RTS and OUT2 */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_MCR),
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COMPORT_MCR_DTR | COMPORT_MCR_RTS | COMPORT_MCR_OUT2);
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/* Enable FIFO */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_FCR),
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COMPORT_FCR_ENABLE | COMPORT_FCR_RCVR_RESET | COMPORT_FCR_TXMT_RESET);
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/* Mark port as fully initialized */
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Flags |= COMPORT_FLAG_INIT;
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/* Make sure port works in Normal Operation Mode (NOM) */
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HlIoPortOutByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_MCR), COMPORT_MCR_NOM);
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/* Read junk data out of the Receive Buffer Register (RBR) */
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HlIoPortInByte(PtrToUshort(PortAddress + (ULONG)COMPORT_REG_RBR));
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/* Store port details */
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Port->Address = PortAddress;
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Port->Baud = BaudRate;
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Port->Flags = Flags;
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Port->Ring = 0;
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/* Return success */
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return STATUS_SUCCESS;
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}
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