376 lines
8.4 KiB
C++
376 lines
8.4 KiB
C++
//++
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//
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// Copyright (c) Microsoft Corporation
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//
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// Module Name:
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//
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// blcom.cpp
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//
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// Abstract:
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//
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// This module implements COM port support for the boot loader.
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//
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//--
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#include "bl.h"
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#define COM1_ADDRESS 0x3F8
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#define COM2_ADDRESS 0x2F8
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#define COM3_ADDRESS 0x3E8
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#define COM4_ADDRESS 0x2E8
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const UINT16 BlComBasePort[COM_MAX_PORT + 1] = {
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0,
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COM1_ADDRESS,
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COM2_ADDRESS,
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COM3_ADDRESS,
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COM4_ADDRESS
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};
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#define COM_DATA_REGISTER 0x0000
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#define COM_INTERRUPT_ENABLE_REGISTER 0x0001
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#define COM_INTERRUPT_IDENTIFICATION_REGISTER 0x0002
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#define COM_FIFO_CONTROL_REGISTER 0x0002
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#define COM_LINE_CONTROL_REGISTER 0x0003
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#define COM_MODEM_CONTROL_REGISTER 0x0004
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#define COM_LINE_STATUS_REGISTER 0x0005
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#define COM_MODEM_STATUS_REGISTER 0x0006
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#define COM_SCRATCH_REGISTER 0x0007
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#define COM_DIVISOR_LATCH_REGISTER_LOW 0x0000
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#define COM_DIVISOR_LATCH_REGISTER_HIGH 0x0001
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#define COM_CLOCK_RATE 0x1C200
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#define COM_LINE_CONTROL_8BITS_1STOP 0x03
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#define COM_LINE_CONTROL_DIVISOR_ACCESS 0x80
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#define COM_MODEM_CONTROL_DATA_TERMINAL_READY 0x01
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#define COM_MODEM_CONTROL_REQUEST_TO_SEND 0x02
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#define COM_LINE_STATUS_DATA_READY 0x01
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#define COM_LINE_STATUS_OVERRUN_ERROR 0x02
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#define COM_LINE_STATUS_PARITY_ERROR 0x04
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#define COM_LINE_STATUS_FRAMING_ERROR 0x08
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#define COM_LINE_STATUS_SEND_BUFFER_EMPTY 0x20
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BOOLEAN
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BlComInitialize(
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UINT8 PortNumber,
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UINT32 BaudRate
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)
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//++
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//
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// Routine Description:
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//
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// This function initializes the specified COM port.
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//
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// Arguments:
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//
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// PortNumber - Supplies the number of the port to initialize.
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//
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// BaudRate - Supplies the baud rate.
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//
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// Return Value:
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//
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// TRUE, if initialization was successful.
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// FALSE, otherwise.
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//
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//--
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{
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UINT16 Base;
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UINT16 Divisor;
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UINT8 Index;
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UINT8 Status;
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BLASSERT((PortNumber >= 1) && (PortNumber <= COM_MAX_PORT));
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BLASSERT(BaudRate != 0);
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BLASSERT(BaudRate <= COM_CLOCK_RATE);
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BLASSERT((COM_CLOCK_RATE % BaudRate) == 0);
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BLASSERT((COM_CLOCK_RATE / BaudRate) <= 0x10000);
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Base = BlComBasePort[PortNumber];
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BlRtlWritePort8(Base + COM_LINE_CONTROL_REGISTER, 0);
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BlRtlWritePort8(Base + COM_INTERRUPT_ENABLE_REGISTER, 0);
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BlRtlWritePort8(Base + COM_MODEM_CONTROL_REGISTER, COM_MODEM_CONTROL_DATA_TERMINAL_READY | COM_MODEM_CONTROL_REQUEST_TO_SEND);
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Divisor = (UINT16) (COM_CLOCK_RATE / BaudRate);
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BlRtlWritePort8(Base + COM_LINE_CONTROL_REGISTER, COM_LINE_CONTROL_DIVISOR_ACCESS);
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BlRtlWritePort8(Base + COM_DIVISOR_LATCH_REGISTER_LOW, (UINT8) (Divisor & 0xFF));
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BlRtlWritePort8(Base + COM_DIVISOR_LATCH_REGISTER_HIGH, (UINT8) (Divisor >> 8));
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BlRtlWritePort8(Base + COM_LINE_CONTROL_REGISTER, COM_LINE_CONTROL_8BITS_1STOP);
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Index = 0;
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do {
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BlRtlWritePort8(Base + COM_SCRATCH_REGISTER, Index);
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if (BlRtlReadPort8(Base + COM_SCRATCH_REGISTER) != Index) {
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return FALSE;
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}
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Index += 1;
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} while (Index != 0);
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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if (Status == 0xFF) {
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return FALSE;
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}
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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return TRUE;
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}
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BOOLEAN
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BlComSendByte(
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UINT8 PortNumber,
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UINT8 Byte
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)
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//++
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//
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// Routine Description:
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//
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// This function sends a byte to the specified COM port.
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//
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// Arguments:
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//
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// PortNumber - Supplies the number of the port to send to.
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//
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// Byte - Supplies the byte to send.
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//
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// Return Value:
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//
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// TRUE, if data was sent.
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// FALSE, otherwise.
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//
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//--
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{
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UINT16 Base;
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UINT8 Status;
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BLASSERT((PortNumber >= 1) && (PortNumber <= COM_MAX_PORT));
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Base = BlComBasePort[PortNumber];
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do {
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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} while ((Status & COM_LINE_STATUS_SEND_BUFFER_EMPTY) == 0);
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BlRtlWritePort8(Base + COM_DATA_REGISTER, Byte);
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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return TRUE;
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}
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BOOLEAN
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BlComDataAvailable(
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UINT8 PortNumber
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)
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//++
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//
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// Routine Description:
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//
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// This function checks if data is available at the specified COM port.
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//
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// Arguments:
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//
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// PortNumber - Supplies the number of the port to check.
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//
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// Return Value:
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//
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// TRUE, if data is available.
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// FALSE, otherwise.
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//
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//--
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{
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UINT16 Base;
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UINT8 Status;
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BLASSERT((PortNumber >= 1) && (PortNumber <= COM_MAX_PORT));
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Base = BlComBasePort[PortNumber];
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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return ((Status & COM_LINE_STATUS_DATA_READY) != 0);
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}
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UINT8
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BlComReceiveByte(
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UINT8 PortNumber
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)
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//++
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//
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// Routine Description:
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//
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// This function receives a byte from the specified COM port.
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//
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// Arguments:
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//
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// PortNumber - Supplies the number of the port to receive from.
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//
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// Return Value:
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//
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// Byte received from the specified COM port.
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//
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//--
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{
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UINT16 Base;
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UINT8 Byte;
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UINT8 Status;
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BLASSERT((PortNumber >= 1) && (PortNumber <= COM_MAX_PORT));
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Base = BlComBasePort[PortNumber];
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BlRtlReadPort8(Base + COM_MODEM_STATUS_REGISTER);
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do {
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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} while ((Status & COM_LINE_STATUS_DATA_READY) == 0);
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Byte = BlRtlReadPort8(Base + COM_DATA_REGISTER);
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Status = BlRtlReadPort8(Base + COM_LINE_STATUS_REGISTER);
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#if COM_VERBOSE
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if ((Status & COM_LINE_STATUS_OVERRUN_ERROR) != 0) {
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BlVideoPrintf("COM%u: Overrun error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_PARITY_ERROR) != 0) {
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BlVideoPrintf("COM%u: Parity error!\n", PortNumber);
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}
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if ((Status & COM_LINE_STATUS_FRAMING_ERROR) != 0) {
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BlVideoPrintf("COM%u: Framing error!\n", PortNumber);
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}
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#endif
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return Byte;
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}
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