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/*
* This file is part of SerialPundit.
*
* Copyright (C) 2014-2016, Rishi Gupta. All rights reserved.
*
* The SerialPundit is DUAL LICENSED. It is made available under the terms of the GNU Affero
* General Public License (AGPL) v3.0 for non-commercial use and under the terms of a commercial
* license for commercial use of this software.
*
* The SerialPundit is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/
package com.serialpundit.serial.ftp;
import java.io.File;
import java.io.FileInputStream;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import com.serialpundit.core.util.SerialComCRCUtil;
import com.serialpundit.core.SerialComPlatform;
import com.serialpundit.core.SerialComTimeOutException;
import com.serialpundit.core.SerialComException;
import com.serialpundit.serial.SerialComManager;
/**
* Implements YMODEM-1K file transfer protocol state machine in Java.
*
* @author Rishi Gupta
*/
public final class SerialComYModem1K {
private final byte SOH = 0x01; // Start of header character
private final byte STX = 0x02; // Start of text character
private final byte EOT = 0x04; // End-of-transmission character
private final byte ACK = 0x06; // Acknowledge byte character
private final byte NAK = 0x15; // Negative-acknowledge character
private final byte CAN = 0x18; // Cancel
private final byte SUB = 0x1A; // Substitute/CTRL+Z
private final byte C = 0x43; // ASCII capital C character
private final byte CR = 0x0D; // Carriage return
private final byte LF = 0x0A; // Line feed
private final byte BS = 0X08; // Back space
private final byte SPACE = 0x20; // Space
private final SerialComManager scm;
private final long handle;
private File[] filesToSend;
private String currentlySendingFileName;
private long lengthOfFileToSend;
private File filesToReceive;
private final boolean textMode;
private final ISerialComYmodemProgress progressListener;
private final SerialComFTPCMDAbort transferState;
private final int osType;
private int blockNumber;
private byte[] block = new byte[1029]; // 1029 bytes ymodem info or data block/packet
private byte[] block0 = null;
private BufferedInputStream inStream; // sent file from local to remote system
private BufferedOutputStream outStream; // received file from remote to local system
private boolean noMoreData;
private boolean isFirstDataBytePending = false;
private boolean isSecondDataBytePending = false;
private boolean isThirdDataBytePending = false;
private boolean isLineFeedPending = false;
private boolean isCarriageReturnPending = false;
private byte firstPendingDataByte;
private byte secondPendingDataByte;
private byte thirdPendingDataByte;
private boolean alreadySentEOFchar = false;
private byte[] tmpSendBuffer = new byte[2048];
private byte[] tmpReceiveBuffer = new byte[2526];
private int mark = -1;
private int limit = -1;
private boolean lastCharacterReceivedWasLF = false;
private boolean lastCharacterReceivedWasCR = false;
private boolean unprocessedByteInReceivedDataExist = false;
private byte unprocessedByteInLastReceivedBlock;
private byte data0 = 0;
private byte data1 = 0;
private long numberOfBlocksSent = 0; // track how many blocks have been sent till now.
private long numberOfBlocksReceived = 0; // track how many blocks have been received till now.
private boolean lastCharacterReceivedWasCAN = false;
private int currentlyProcessingFilenumber = 0;
private final byte ABORT_CMD[] = new byte[] { CAN, CAN, CAN, CAN, CAN, BS, BS, BS, BS, BS };
private final SerialComCRCUtil crcCalculator = new SerialComCRCUtil();
/**
* Allocates a new SerialComYModem1K object with given details and associate it with the given
* instance of SerialComManager class. This is used for sending files.
*
* @param scm SerialComManager instance associated with this handle.
* @param handle of the port on which file is to be communicated.
* @param filesToSend all the files to be sent to the receiver end.
* @param textMode if true file will be sent as text file (ASCII mode), if false file will be sent
* as binary file.
* @param progressListener object of class which implements ISerialComYmodemProgress interface and is
* interested in knowing how many blocks have been sent/received till now.
* @param transferState if application wish to abort sending/receiving file at instant of time due to
* any reason, it can call abortTransfer method on this object. It can be null if application
* does not wish to abort sending/receiving file explicitly.
* @param osType operating system on which this application is running.
*/
public SerialComYModem1K(SerialComManager scm, long handle, File[] filesToSend, boolean textMode,
ISerialComYmodemProgress progressListener, SerialComFTPCMDAbort transferState, int osType) {
this.scm = scm;
this.handle = handle;
this.filesToSend = filesToSend;
this.textMode = textMode;
this.progressListener = progressListener;
this.transferState = transferState;
this.osType = osType;
}
/**
* Allocates a new SerialComYModem1K object with given details and associate it with the given
* instance of SerialComManager class. This is used for receiving files.
*
* @param scm SerialComManager instance associated with this handle.
* @param handle of the port on which file is to be communicated.
* @param filesToReceive folder in which all files received will be placed.
* @param textMode if true file will be sent as text file (ASCII mode), if false file will be sent
* as binary file.
* @param progressListener object of class which implements ISerialComYmodemProgress interface and is
* interested in knowing how many blocks have been sent/received till now.
* @param transferState if application wish to abort sending/receiving file at instant of time due to
* any reason, it can call abortTransfer method on this object. It can be null if application
* does not wish to abort sending/receiving file explicitly.
* @param osType operating system on which this application is running.
*/
public SerialComYModem1K(SerialComManager scm, long handle, File filesToReceive, boolean textMode,
ISerialComYmodemProgress progressListener, SerialComFTPCMDAbort transferState, int osType) {
this.scm = scm;
this.handle = handle;
this.filesToReceive = filesToReceive;
this.textMode = textMode;
this.progressListener = progressListener;
this.transferState = transferState;
this.osType = osType;
}
/**
* Represents actions to execute in state machine to implement ymodem-1k protocol
* for sending files.
*
* @return true on success, false if application instructed to abort.
* @throws SecurityException if unable to read from file to be sent.
* @throws IOException if any I/O error occurs.
* @throws SerialComException if any I/0 error on serial port communication occurs.
*/
public boolean sendFileY() throws IOException {
// Finite state machine's states.
final int CONNECT = 0x01;
final int BLOCK0SEND = 0x02;
final int BEGINSEND = 0x03;
final int WAITACK = 0x04;
final int RESEND = 0x05;
final int SENDNEXT = 0x06;
final int ENDTX = 0x07;
final int ABORT = 0x08;
final int FINISHTX = 0x09;
boolean cReceived = false;
boolean eotAckReceptionTimerInitialized = false;
boolean needToSendBlock0 = true;
boolean waitForBlock0ACK = true;
boolean waitForFinalBlockACK = false;
String errMsg = null;
int retryCount = 0;
int state = -1;
byte[] data = null;
long responseWaitTimeOut = 0;
long eotAckWaitTimeOutValue = 0;
int percentOfBlocksSent = 0;
boolean finAckReceptionTimerInitialized = false;
long finAckWaitTimeOutValue = 0;
boolean showSentProgress = false;
currentlySendingFileName = filesToSend[currentlyProcessingFilenumber].getName();
lengthOfFileToSend = filesToSend[currentlyProcessingFilenumber].length();
inStream = new BufferedInputStream(new FileInputStream(filesToSend[currentlyProcessingFilenumber]));
state = CONNECT;
while(true) {
switch(state) {
case CONNECT:
cReceived = false;
responseWaitTimeOut = System.currentTimeMillis() + 60000;
while(cReceived != true) {
try {
data = scm.readBytes(handle, 1024);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
if((data != null) && (data.length > 0)) {
/* Instead of purging receive buffer and then waiting for C, receive all data because
* this approach might be faster. The other side might have opened first time and may
* have flushed garbage data. So receive buffer may contain garbage + C character. */
for(int x=0; x < data.length; x++) {
if(data[x] == C) {
cReceived = true;
if(needToSendBlock0 == true) {
state = BLOCK0SEND;
}else {
state = BEGINSEND;
}
break;
}
}
}else {
try {
Thread.sleep(100); // delay before next attempt to check C character reception.
} catch (InterruptedException e) {
}
// abort if timed-out while waiting for C character.
if((cReceived != true) && (System.currentTimeMillis() >= responseWaitTimeOut)) {
errMsg = "Timedout while waiting for file receiver to initiate connection setup !";
state = ABORT;
break;
}
}
// check if application (file sender) wish to cancel sending file.
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
inStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
}
break;
case BLOCK0SEND:
if(retryCount > 10) {
errMsg = "Maximum number of retries reached while sending block 0 to receiver end !";
state = ABORT;
break;
}
assembleBlock0();
try {
scm.writeBytes(handle, block0, 0);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
needToSendBlock0 = false;
waitForBlock0ACK = true;
showSentProgress = false;
state = WAITACK;
break;
case BEGINSEND:
block0 = null; // free memory
blockNumber = 1; // Block numbering starts from 1 for the first data block sent.
assembleBlock();
// if the file is empty goto ENDTX state.
if(noMoreData == true) {
state = ENDTX;
break;
}
try {
scm.writeBytes(handle, block, 0);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
showSentProgress = true;
state = WAITACK;
break;
case RESEND:
if(retryCount > 10) {
errMsg = "Maximum number of retries reached while sending same data block !";
state = ABORT;
break;
}
try {
scm.writeBytes(handle, block, 0);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
showSentProgress = true;
state = WAITACK;
break;
case WAITACK:
responseWaitTimeOut = System.currentTimeMillis() + 60000; // 1 minute.
while(true) {
// check if application (file sender) wish to cancel sending file.
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
inStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
// delay before next attempt to read from serial port
try {
if(noMoreData != true) {
Thread.sleep(120);
}else {
// give sufficient time to remote end to close file resources and be able to
// acknowledge us happily.
Thread.sleep(250);
}
} catch (InterruptedException e) {
}
// try to read data from serial port
try {
data = scm.readBytes(handle, 1);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
/* if data received process it. if long timeout occurred abort otherwise retry reading from serial port.
* if nothing received at all abort. */
if((data != null) && (data.length > 0)) {
break;
}else {
if(noMoreData == true) {
state = ENDTX;
break;
}
if(System.currentTimeMillis() >= responseWaitTimeOut) {
if(noMoreData == true) {
errMsg = "Timedout while waiting for EOT reception acknowledgement from file receiver !";
}else if(waitForBlock0ACK == true) {
errMsg = "Timedout while waiting for block0 reception acknowledgement from file receiver !";
}else {
errMsg = "Timedout while waiting for block reception acknowledgement from file receiver !";
}
state = ABORT;
break;
}
}
}
if(state == WAITACK) {
if(noMoreData != true) {
if(data[0] == ACK) {
if(lastCharacterReceivedWasCAN == true) {
// is invalid sequence.
if(waitForBlock0ACK != true) {
retryCount++;
state = RESEND;
}else {
retryCount++;
state = BLOCK0SEND;
}
break;
}
if(waitForBlock0ACK != true) {
state = SENDNEXT;
}else {
state = CONNECT;
waitForBlock0ACK = false;
}
}else if(data[0] == NAK) {
// indicates both only and sequence reception.
if(waitForBlock0ACK != true) {
retryCount++;
state = RESEND;
}else {
retryCount++;
state = BLOCK0SEND;
}
}else if(data[0] == CAN) {
if(data.length >= 2) {
if(data[1] == CAN) {
errMsg = "Received abort command from file receiving end !";
state = ABORT;
break;
}else {
// probably it is noise, so re-send block.
if(waitForBlock0ACK != true) {
retryCount++;
state = RESEND;
}else {
retryCount++;
state = BLOCK0SEND;
}
}
}
if(lastCharacterReceivedWasCAN == true) {
errMsg = "Received abort command from file receiving end !";
state = ABORT;
break;
}
lastCharacterReceivedWasCAN = true;
}else {
errMsg = "Invalid data byte : " + data[0] + " received from file receiver !";
state = ABORT;
break;
}
// update GUI that a block has been sent if application has provided a listener
// for this purpose.
if(showSentProgress == true) {
if(progressListener != null) {
numberOfBlocksSent++;
if(lengthOfFileToSend != 0) {
percentOfBlocksSent = (int) ((102400 * numberOfBlocksSent) / lengthOfFileToSend);
}else {
percentOfBlocksSent = 100;
}
if(percentOfBlocksSent >= 100) {
percentOfBlocksSent = 100;
}
progressListener.onYmodemSentProgressUpdate(currentlySendingFileName, numberOfBlocksSent, percentOfBlocksSent);
}
}
}else {
// if there is no more data to be sent, we are looking for ACK after sending EOT.
if(data[0] == ACK) {
if(waitForFinalBlockACK == true) {
// successfully sent all files, let's go back home happily.
return true;
}else {
inStream.close();
currentlyProcessingFilenumber++;
if(currentlyProcessingFilenumber >= filesToSend.length) {
state = FINISHTX;
break;
}
// send next file, reset all stuff
lengthOfFileToSend = filesToSend[currentlyProcessingFilenumber].length();
inStream = new BufferedInputStream(new FileInputStream(filesToSend[currentlyProcessingFilenumber]));
cReceived = false;
eotAckReceptionTimerInitialized = false;
retryCount = 0;
responseWaitTimeOut = 0;
eotAckWaitTimeOutValue = 0;
percentOfBlocksSent = 0;
needToSendBlock0 = true;
noMoreData = false;
alreadySentEOFchar = false;
isFirstDataBytePending = false;
isSecondDataBytePending = false;
isThirdDataBytePending = false;
isLineFeedPending = false;
isCarriageReturnPending = false;
mark = -1;
limit = -1;
lastCharacterReceivedWasLF = false;
lastCharacterReceivedWasCR = false;
unprocessedByteInReceivedDataExist = false;
lastCharacterReceivedWasCAN = false;
data0 = 0;
data1 = 0;
state = CONNECT;
}
break;
}else if(data[0] == CAN) {
// receiver might have sent us abort command while we were sending EOT to it.
errMsg = "Received abort command from file receiving end !";
state = ABORT;
break;
}else {
if(waitForFinalBlockACK != true) {
if(System.currentTimeMillis() >= eotAckWaitTimeOutValue) {
errMsg = "Timedout while waiting for EOT reception acknowledgement !";
state = ABORT;
}else {
// re-send EOT (try more times), this also handles the NAK received case.
state = ENDTX;
}
}else {
if(System.currentTimeMillis() >= finAckWaitTimeOutValue) {
errMsg = "Timedout while waiting for final ymodem null block reception acknowledgement !";
state = ABORT;
}else {
// re-send ymodem final null block (try more times), this also handles the NAK received case.
state = FINISHTX;
}
}
}
}
}
else {
}
break;
case SENDNEXT:
retryCount = 0; // reset
blockNumber++;
assembleBlock();
// indicates there is no more data to be sent.
if(noMoreData == true) {
state = ENDTX;
break;
}
// reaching here means there is data to be sent to receiver.
try {
scm.writeBytes(handle, block, 0);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
showSentProgress = true;
state = WAITACK;
break;
case ENDTX:
if(eotAckReceptionTimerInitialized != true) {
eotAckWaitTimeOutValue = System.currentTimeMillis() + 60000; // 1 minute
eotAckReceptionTimerInitialized = true;
}
try {
scm.writeSingleByte(handle, EOT);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
numberOfBlocksSent = 0; // reset
showSentProgress = false;
state = WAITACK;
break;
case FINISHTX:
if(finAckReceptionTimerInitialized != true) {
finAckWaitTimeOutValue = System.currentTimeMillis() + 60000; // 1 minute
finAckReceptionTimerInitialized = true;
assembleFinalBlock();
}
try {
scm.writeBytes(handle, block, 0);
} catch (SerialComException exp) {
inStream.close();
throw exp;
}
waitForFinalBlockACK = true;
showSentProgress = false;
state = WAITACK;
break;
case ABORT:
/* if any exception occurs, control will not reach here instead exception would
* have been already thrown. This state is entered explicitly to abort executing
* actions in state machine. */
inStream.close();
throw new SerialComTimeOutException(errMsg);
default:
break;
}
}
}
/*
* Prepares ymodem/crc block 0 of 133/1029 bytes in total using CRC-16-CCITT as given below :
* [SOH/STX][0x00][0xFF][file name\0][file length][space][file modification info][space][file mode][space][padding][2 byte CRC]
*/
private void assembleBlock0() throws IOException {
int g = 0;
int k = 0;
int blockCRCval = 0;
byte[] lenfm = null;
// file name (null terminated)
currentlySendingFileName = filesToSend[currentlyProcessingFilenumber].getName();
byte[] nameb = currentlySendingFileName.getBytes();
// file length in bytes
long fileLength = filesToSend[currentlyProcessingFilenumber].length();
String lenstr = String.valueOf(fileLength);
byte[] lenb = lenstr.getBytes();
// file modification date information
long filemoddate = filesToSend[currentlyProcessingFilenumber].lastModified();
String fmdstr = Long.toOctalString(filemoddate);
byte[] lenfmd = fmdstr.getBytes();
// file mode if os is unix-like
if(osType != SerialComPlatform.OS_WINDOWS) {
String fmstr = Long.toOctalString(0x8000);
lenfm = fmstr.getBytes();
}
if(lenfm == null) {
g = 3 + nameb.length + 1 + lenb.length + 1 + lenfmd.length + 2;
}else {
g = 3 + nameb.length + 1 + lenb.length + 1 + lenfmd.length + 1 + lenfm.length + 2;
}
// populate information gathered about file
if(g <= 133) {
block0 = new byte[133];
block0[0] = SOH;
}else {
block0 = new byte[1029];
block0[0] = STX;
}
block0[1] = (byte) 0x00;
block0[2] = (byte) 0xFF;
g = 3;
for(k=0; k < nameb.length; k++) {
block0[g] = nameb[k];
g++;
}
block0[g] = '\0';
g++;
for(k=0; k < lenb.length; k++) {
block0[g] = lenb[k];
g++;
}
block0[g] = SPACE;
g++;
for(k=0; k < lenfmd.length; k++) {
block0[g] = lenfmd[k];
g++;
}
block0[g] = SPACE;
g++;
if(lenfm != null) {
for(k=0; k < lenfm.length; k++) {
block0[g] = lenfm[k];
g++;
}
}else {
block0[g] = (byte) 0x00;
g++;
}
block0[g] = SPACE;
g++;
// padding
for(k=g; k <= (block0.length - 3); k++) {
block0[k] = (byte) 0x00;
}
// append 2 byte CRC value.
blockCRCval = crcCalculator.getCRC16CCITTValue(block0, 3, (block0.length - 3));
block0[block0.length - 2] = (byte) (blockCRCval >>> 8); // CRC high byte
block0[block0.length - 1] = (byte) blockCRCval; // CRC low byte
}
/*
* Prepares ymodem/crc block indicating that the sender has sent all the files.
* [SOH][0x00][0xFF][128 times 0x00][2 byte CRC]
*/
private void assembleFinalBlock() throws IOException {
int blockCRCval = 0;
block[0] = SOH;
block[1] = (byte) 0x00;
block[2] = (byte) 0xFF;
for(int d=0; d<128; d++) {
block[d+3] = (byte) 0x00;
}
blockCRCval = crcCalculator.getCRC16CCITTValue(block, 3, 130);
block[131] = (byte) (blockCRCval >>> 8);
block[132] = (byte) blockCRCval;
}
/*
* Prepares ymodem-1k block of 1029 bytes in total using CRC-16-CCITT as given below :
* [SOH][blk #][255-blk #][1024 data bytes][2 byte CRC]
*
* For text mode transfer, lines are terminated by CR+LF, EOF will be indicate
* by one or more ^Z. If the data ends exactly on a 1024-byte boundary, i.e.
* CR in 1023, and LF in 1024, a subsequent sector containing the ^Z EOF character(s)
* will be sent. This method handles text/ascii mode in operating system independent
* way.
*
* This algorithm for processing assumes that a text file may contain following combinations
* of character sequence with the corresponding data bytes sent to receiving end. The X
* is a data byte other than CR and LF.
*
* CR LF (send CR LF)
* CR CR (send CR LF CR LF)
* CR X (send CR LF X)
* LF CR (send CR LF)
* LF LF (send CR LF CR LF)
* LF X (send CR LF X)
* X X (send X X)
* X LF (send X CR LF)
* X CR (send X CR LF)
*
* This algorithm algorithm takes 2 bytes at a time into consideration and check it against the
* above combination. Based on cases above, it will add/remove CR and LF etc characters if
* required.
*
* For text mode data is first read into tmpSendBuffer and then parsed.
* mark - points to current byte which needs to be sent to other end
* limit - refers to number of bytes currently available in tmpSendBuffer
*
* If we need to add extra LF or CR characters, it may be added in current block if there
* is space or it will be added in next block if current block is full.
*
* @throws IOException if any I/O error occurs.
*/
private void assembleBlock() throws IOException {
int x = 0;
int numBytesRead = 0;
int blockCRCval = 0;
// starts at 01 increments by 1, and wraps 0FFH to 00H (not to 01).
if(blockNumber > 0xFF) {
blockNumber = 0x00;
}
block[0] = STX;
block[1] = (byte) blockNumber;
block[2] = (byte) ~blockNumber;
if(textMode == true) {
/* file is to be send as a text file. */
// set index at which first data byte will be saved to send.
x = 3;
if(isFirstDataBytePending == true) {
block[x] = firstPendingDataByte;
x++;
isFirstDataBytePending = false; // reset
if(isSecondDataBytePending == true) {
block[x] = secondPendingDataByte;
x++;
isSecondDataBytePending = false; // reset
if(isThirdDataBytePending == true) {
block[x] = thirdPendingDataByte;
x++;
isThirdDataBytePending = false; // reset
}
}
}
while(x < 1027) {
// entering into this loop means that at-least one byte
// of space exist in block[] array.
if((mark == limit) || (mark == -1)) {
// indicates we need to read more data from file as all data bytes in
// tmpSendBuffer has been sent to file receiver end.
limit = inStream.read(tmpSendBuffer, 0, 2048);
mark = 0; // reset mark.
if(limit < 0) {
// 0 bytes; EOF reached.
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = -1;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = -1;
}else {
data0 = -1;
data1 = -1;
}
}else if(limit == 1) {
// 1 byte (last byte) of data in file.
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else {
data0 = tmpSendBuffer[mark];
mark++;
data1 = -1;
}
}else {
// 2 or more data bytes are there in file.
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else {
data0 = tmpSendBuffer[mark];
mark++;
data1 = tmpSendBuffer[mark];
mark++;
}
}
}else if(mark == (limit - 1)) {
// indicates mark is at last byte of tmpSendBuffer and therefore
// 1 more data byte is needed (to be placed in data1 variable).
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else {
data0 = tmpSendBuffer[mark];
mark++;
limit = inStream.read(tmpSendBuffer, 0, 1024);
mark = 0; // reset mark.
if(limit < 0) {
data1 = -1;
}else {
data1 = tmpSendBuffer[mark];
mark++;
}
}
}else if((mark == 0) && (limit == -1)) {
// indicates there is no more data to be sent.
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = -1;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = -1;
}else {
data0 = -1;
data1 = -1;
}
}else {
// indicates mark is at position from where 2 bytes in tmpSendBuffer
// are available to be analyzed.
if(isLineFeedPending == true) {
data0 = LF;
isLineFeedPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else if(isCarriageReturnPending == true) {
data0 = CR;
isCarriageReturnPending = false; // reset
data1 = tmpSendBuffer[mark];
mark++;
}else {
data0 = tmpSendBuffer[mark];
mark++;
data1 = tmpSendBuffer[mark];
mark++;
}
}
// When control reached here, both data0 and data1 will have valid values.
// so algorithm will work with 2 given bytes. The data0/data1 may contain
// a printable character which can have negative value therefore allow data0
// and data1 to contain anything other than -1.
if(data0 == -1) {
// indicates EOF reached.
if(alreadySentEOFchar == true) {
// EOF have been sent already in last block.
noMoreData = true;
return;
}else {
// assemble last block with ^Z padding. if x == 3,
// whole block will contain ^Z only as data bytes.
for(x = x + 0; x < 1027; x++) {
block[x] = SUB;
}
alreadySentEOFchar = true;
}
}else if((data0 != -1) && (data1 == -1)) {
// indicates last byte of data in file.
if((data0 == LF) || (data0 == CR)) {
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
}else {
// now LF character will be sent in next block
isFirstDataBytePending = true;
firstPendingDataByte = LF;
}
}else {
block[x] = data0;
x++;
}
}else {
// indicates 2 bytes of data are there and need to be processed.
if((data0 != LF) && (data0 != CR)) {
if((data1 != LF) && (data1 != CR)) {
// indicates XX case.
block[x] = data0;
x++;
if(x < 1027) {
block[x] = data1;
x++;
}else {
isFirstDataBytePending = true;
firstPendingDataByte = data1;
}
}else if(data1 == LF) {
// indicates XLF case.
block[x] = data0;
x++;
isLineFeedPending = true;
}else {
// indicates XCR case.
block[x] = data0;
x++;
isCarriageReturnPending = true;
}
}else if(((data0 == CR) && (data1 == LF)) || ((data0 == LF) && (data1 == CR))) {
// indicates LFCR or CRLF case.
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
}else {
isFirstDataBytePending = true;
firstPendingDataByte = LF;
}
}else if((data0 == LF) && (data1 != CR) && (data1 != LF)) {
// indicates LFX case.
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
if(x < 1027) {
block[x] = data1;
x++;
}else {
isFirstDataBytePending = true;
firstPendingDataByte = data1;
}
}else {
isFirstDataBytePending = true;
firstPendingDataByte = LF;
isSecondDataBytePending = true;
secondPendingDataByte = data1;
}
}else if((data0 == CR) && (data1 != CR) && (data1 != LF)) {
// indicates CRX case.
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
if(x < 1027) {
block[x] = data1;
x++;
}else {
isFirstDataBytePending = true;
firstPendingDataByte = data1;
}
}else {
isFirstDataBytePending = true;
firstPendingDataByte = LF;
isSecondDataBytePending = true;
secondPendingDataByte = data1;
}
}else if(((data0 == LF) && (data1 == LF)) || ((data0 == CR) && (data1 == CR))) {
// indicates LFLF or CRCR case.
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
if(x < 1027) {
block[x] = CR;
x++;
if(x < 1027) {
block[x] = LF;
x++;
}else {
isFirstDataBytePending = true;
firstPendingDataByte = LF;
}
}else {
isFirstDataBytePending = true;
firstPendingDataByte = CR;
isSecondDataBytePending = true;
secondPendingDataByte = LF;
}
}else {
isFirstDataBytePending = true;
firstPendingDataByte = LF;
isSecondDataBytePending = true;
secondPendingDataByte = CR;
isThirdDataBytePending = true;
thirdPendingDataByte = LF;
}
}else {
}
}
} // end while loop
}else {
/* file is to be send as a binary file. */
// read data from the file to be sent.
numBytesRead = inStream.read(block, 3, 1024);
if(numBytesRead == 1024) {
}else if(numBytesRead > 0) {
// assembling last block with padding.
for(x = numBytesRead + 3; x < 1027; x++) {
block[x] = SUB;
}
}else {
// EOF encountered.
noMoreData = true;
return;
}
}
// append 2 byte CRC value.
blockCRCval = crcCalculator.getCRC16CCITTValue(block, 3, 1026);
block[1027] = (byte) (blockCRCval >>> 8); // CRC high byte
block[1028] = (byte) blockCRCval; // CRC low byte
}
/**
* Represents actions to execute in state machine to implement ymodem-1k protocol for
* receiving files.
*
* @return true on success, false if application instructed to abort.
* @throws IOException if any I/O error occurs.
* @throws SerialComException if any I/0 error on serial port communication occurs.
*/
public boolean receiveFileY() throws IOException {
// Finite state machine's states.
final int CONNECT = 0x01;
final int BLOCK0RCV = 0x02;
final int PBLOCK0 = 0x03;
final int BEGINRCV = 0x04;
final int DATABLOCKRCV = 0x05;
final int VERIFY = 0x06;
final int REPLY = 0x07;
final int ABORT = 0x08;
int i = 0;
int x = 0;
int crcl = 0;
int state = -1;
int blockNumber = 1;
int blockCRCval = 0;
int block0Index = 0;
int dataBlockIndex = 0;
byte[] data = null;
String errMsg = null;
int spaceLeftInBlock0 = 0;
int spaceLeftInDataBlock = 0;
byte[] block133 = new byte[133];
long currentlyProcessingFileLength = 0;
long currentlyProcessingFileModifyInfo = 0;
long currentlyProcessingFileMode = 0;
boolean isFileOpen = false;
String nameOfFileBeingReceived = null;
final String receiverDirAbsolutePath = filesToReceive.getAbsolutePath();
boolean isCorrupted = false;
boolean isDuplicateBlock = false;
int duplicateBlockRetryCount = 0;
long totalNumberOfDataBytesReadTillNow = 0;
int percentOfBlocksReceived = 0;
// Clear receive buffer before start. Ymodem is fully receiver driven by design.
try {
scm.clearPortIOBuffers(handle, true, false);
} catch (SerialComException exp) {
outStream.close();
throw exp;
}
state = CONNECT; // entry point to state machine.
while(true) {
switch(state) {
case CONNECT:
// reset some globals
blockNumber = 1;
numberOfBlocksReceived = 0;
totalNumberOfDataBytesReadTillNow = 0;
lastCharacterReceivedWasLF = false;
lastCharacterReceivedWasCR = false;
unprocessedByteInReceivedDataExist = false;
for(x=0; x < 3; x++) {
try {
scm.writeSingleByte(handle, C);
} catch (SerialComException e) {
throw e;
}
try {
Thread.sleep(300);
} catch (InterruptedException e) {
}
try {
data = scm.readBytes(handle, 133);
} catch (IOException e) {
throw e;
}
if(data != null && data.length > 0) {
if(data[0] == EOT) {
// sender sent EOT again because he missed (noise) our acknowledgement of EOT previously sent.
try {
scm.writeSingleByte(handle, ACK);
continue;
} catch (IOException e) {
throw e;
}
}
break;
}
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
outStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
}
if(x >= 3) {
throw new SerialComTimeOutException("Timed out while connecting with file sender !");
}
state = BLOCK0RCV;
break;
case BLOCK0RCV:
for(x=0; x < 3; x++) {
if((data != null) && (data.length > 0)) {
if(data[0] == SOH) {
block0 = block133;
spaceLeftInBlock0 = 133;
crcl = 131;
break;
}else if(data[0] == STX) {
block0 = block;
spaceLeftInBlock0 = 1029;
crcl = 1027;
break;
}else {
// the sender might forget to flush his serial port buffers and therefore initial
// data may be garbage + block0.
try {
scm.writeSingleByte(handle, NAK);
} catch (IOException e) {
throw e;
}
try {
Thread.sleep(300);
} catch (InterruptedException e) {
}
try {
data = scm.readBytes(handle, 133);
} catch (IOException e) {
throw e;
}
}
}
}
if(x >= 3) {
throw new SerialComTimeOutException("Timed out while waiting for block 0 from file sender !");
}
for(x=0; x < data.length; x++) {
block0[x] = data[x];
spaceLeftInBlock0--;
}
if(spaceLeftInBlock0 > 0) {
block0Index = block0.length - spaceLeftInBlock0;
for(i = 0; i < 20; i++) {
// check if application (file receiver) wish to cancel receiving file.
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
outStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
// let the data arrive from other end, also minimize JNI transitions.
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
try {
data = scm.readBytes(handle, spaceLeftInBlock0);
} catch (IOException e) {
throw e;
}
if((data != null) && (data.length > 0)) {
for(x=0; x < data.length; x++) {
block0[block0Index] = data[x];
block0Index++;
spaceLeftInBlock0--;
}
}
if(spaceLeftInBlock0 <= 0) {
break;
}
}
}
if(i >= 20) {
throw new SerialComTimeOutException("Timed out while receiving block 0 from file sender !");
}
state = PBLOCK0;
break;
case PBLOCK0:
if((block0[1] != (byte)0x00) || (block0[2] != (byte)0xFF)) {
throw new SerialComException("Invalid information block 0 received !");
}
blockCRCval = crcCalculator.getCRC16CCITTValue(block0, 3, (crcl - 1));
if((block0[crcl] != (byte)(blockCRCval >>> 8)) || (block0[crcl + 1] != (byte)blockCRCval)) {
throw new SerialComException("Invalid CRC (corrupted block 0 or final block received) !");
}
// While we were expecting block 0 file information block, sender might indicate end of session
// as there are no more files to be sent, so check it.
if((block0[crcl] == (byte)0x00) && (block0[crcl + 1] == (byte)0x00)) {
for(i=3; i < block0.length; i++) {
if(block0[i] != (byte)0x00) {
break;
}
}
if(i >= block0.length) {
// All file shave been received, let's go back home happily.
scm.writeSingleByte(handle, ACK);
return true;
}
}
// file name:
// The data bytes get flushed automatically to file system physically whenever
// BufferedOutputStream's internal buffer gets full and request to write more
// bytes have arrived.
for(x=3; x < block0.length; x++) {
if(block0[x] == '\0') {
break;
}
}
nameOfFileBeingReceived = new String(block0, 3, x-3);
if((nameOfFileBeingReceived == null) || (nameOfFileBeingReceived.length() == 0)) {
throw new SerialComException("Sender did not sent file name !");
}
File namefile = new File(receiverDirAbsolutePath, nameOfFileBeingReceived);
if(!namefile.exists()) {
namefile.createNewFile();
}
try {
outStream = new BufferedOutputStream(new FileOutputStream(namefile));
} catch (FileNotFoundException e) {
throw e;
}
isFileOpen = true;
// file length (number of data bytes):
x++;
for(i=x; i < block0.length; i++) {
if(block0[i] == SPACE) {
break;
}
}
currentlyProcessingFileLength = Long.valueOf(new String(block0, x, i - x)).longValue();
// file modification info:
i++;
for(x=i; x < block0.length; x++) {
if(block0[x] == SPACE) {
break;
}
}
currentlyProcessingFileModifyInfo = Long.valueOf(new String(block0, i, x - i), 8);
if(currentlyProcessingFileModifyInfo != 0) {
namefile.setLastModified(currentlyProcessingFileModifyInfo);
}
// file mode:
x++;
for(i=x; i < block0.length; i++) {
if(block0[i] == SPACE) {
break;
}
}
currentlyProcessingFileMode = Long.valueOf(new String(block0, x, i - x), 8);
if(currentlyProcessingFileMode != 0) {
// our translation decision is based on text or binary mode.
}
scm.writeSingleByte(handle, ACK);
state = BEGINRCV;
break;
case BEGINRCV:
try {
scm.writeSingleByte(handle, C);
state = DATABLOCKRCV;
} catch (SerialComException e) {
throw e;
}
state = DATABLOCKRCV;
break;
case DATABLOCKRCV:
dataBlockIndex = 0; // reset
data = null; // reset
state = VERIFY;
i = 0;
while(true) {
try {
Thread.sleep(200);
} catch (InterruptedException e) {
}
try {
data = scm.readBytes(handle, 1);
} catch (IOException e) {
throw e;
}
if((data != null) && (data.length > 0)) {
if(data[0] == SOH) {
block[0] = SOH;
dataBlockIndex++;
spaceLeftInDataBlock = 132;
crcl = 131;
break;
}else if(data[0] == STX) {
block[0] = STX;
dataBlockIndex++;
spaceLeftInDataBlock = 1028;
crcl = 1027;
break;
}else if(data[0] == EOT) {
try {
scm.writeSingleByte(handle, ACK);
if(isFileOpen == true) {
outStream.flush();
outStream.close();
}
isFileOpen = false;
state = CONNECT;
} catch (IOException e) {
errMsg = e.getMessage();
state = ABORT;
}
break;
}else {
}
}
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
outStream.flush();
outStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
if(i > 5) {
break;
}
i++;
}
if(i > 5) {
errMsg = "Timed out while receiving data block from file sender !";
state = ABORT;
break;
}
data = null; // reset
for(i = 0; i < 10; i++) {
// check if application (file receiver) wish to cancel receiving file.
if((transferState != null) && (transferState.isTransferToBeAborted() == true)) {
outStream.close();
scm.writeBytes(handle, ABORT_CMD, 0);
return false;
}
// let the data arrive from other end, also minimize JNI transitions.
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
try {
data = scm.readBytes(handle, spaceLeftInDataBlock);
} catch (IOException e) {
throw e;
}
if((data != null) && (data.length > 0)) {
for(x=0; x < data.length; x++) {
block[dataBlockIndex] = data[x];
dataBlockIndex++;
spaceLeftInDataBlock--;
}
// sender might indicate end of transmission instead of sending next data block
if(block[0] == EOT) {
try {
scm.writeSingleByte(handle, ACK);
if(isFileOpen == true) {
outStream.flush();
outStream.close();
}
isFileOpen = false;
state = CONNECT;
} catch (IOException e) {
state = ABORT;
errMsg = e.getMessage();
}
break;
}
// sender might send transfer abort command instead of next data block
if(block[dataBlockIndex - 1] == CAN) {
if(dataBlockIndex > 1) {
if(block[dataBlockIndex - 2] == CAN) {
state = ABORT;
errMsg = "Abort command received from file sending application !";
break;
}
}
}
}
if(spaceLeftInDataBlock <= 0) {
break;
}
}
if((state == DATABLOCKRCV) && (i >= 10)) {
throw new SerialComTimeOutException("Timed out while receiving data block from file sender !");
}
break;
case VERIFY:
isCorrupted = false; // reset
isDuplicateBlock = false; // reset
state = REPLY;
// verify block start.
if(block[0] == STX) {
}else if(block[0] == SOH) {
}else {
isCorrupted = true;
break;
}
// check duplicate block.
if(block[1] == (byte)(blockNumber - 1)){
isDuplicateBlock = true;
duplicateBlockRetryCount++;
if(duplicateBlockRetryCount > 10) {
errMsg = "Maximum number of retries reached while receiving same data block !";
state = ABORT;
}
break;
}
// verify block number sequence and block number itself.
if((block[1] != (byte) blockNumber) || (block[2] != (byte) ~blockNumber)) {
isCorrupted = true;
break;
}
// verify CRC value.
blockCRCval = crcCalculator.getCRC16CCITTValue(block, 3, (crcl - 1));
if((block[crcl] != (byte)(blockCRCval >>> 8)) || (block[crcl + 1] != (byte)blockCRCval)){
isCorrupted = true;
}
break;
case REPLY:
try {
if(isCorrupted == false) {
// tell sender block has been successfully received
scm.writeSingleByte(handle, ACK);
x = crcl - 3;
totalNumberOfDataBytesReadTillNow = totalNumberOfDataBytesReadTillNow + x;
if(textMode == true) {
// for ASCII mode, parse and then flush.
processAndWrite(block, x);
}else {
// for binary mode, just flush data as is to file physically.
if(currentlyProcessingFileLength != 0) {
if(totalNumberOfDataBytesReadTillNow <= currentlyProcessingFileLength) {
outStream.write(block, 3, x);
}else {
outStream.write(block, 3, (int)(x - (totalNumberOfDataBytesReadTillNow - currentlyProcessingFileLength)));
}
}else {
outStream.write(block, 3, x);
}
}
// update GUI that a block has been received if application has provided
// a listener for this purpose.
if(progressListener != null) {
numberOfBlocksReceived++;
if(currentlyProcessingFileLength > 0) {
percentOfBlocksReceived = (int) ((x * numberOfBlocksReceived * 100) / currentlyProcessingFileLength);
}else {
percentOfBlocksReceived = 100;
}
if(percentOfBlocksReceived >= 100) {
percentOfBlocksReceived = 100;
}
progressListener.onYmodemReceiveProgressUpdate(nameOfFileBeingReceived, numberOfBlocksReceived, percentOfBlocksReceived);
}
if(isDuplicateBlock == false) {
blockNumber++;
if(blockNumber > 0xFF) {
blockNumber = 0x00;
}
duplicateBlockRetryCount = 0; // reset
}
}else {
scm.writeSingleByte(handle, NAK);
}
state = DATABLOCKRCV;
} catch (IOException e) {
throw e;
}
break;
case ABORT:
if(isFileOpen == true) {
outStream.flush();
outStream.close();
}
throw new SerialComException(errMsg);
default:
// never reached
}
}
}
/*
* This algorithm strip all ^Z characters from received data. Further it will add or remove
* CR and LF characters as needed based on operating system this application is running on.
* It process 2 consecutive bytes at a time and handle the following cases (where X represent
* any byte other than CR, LF and ^Z) :
*
* LF LF,
* LF CR,
* LF ^Z,
* LF X,
* CR CR,
* CR LF,
* CR ^Z,
* CR X,
* ^Z ^Z,
* ^Z CR,
* ^Z LF,
* ^Z X,
* X X,
* X CR,
* X LF,
* X ^Z
*
* It is possible that last data byte (130th or 1026th byte) in current block can not be processed
* because we have to analyze next data byte which will be available to us only in the next data
* block received. So we save that last byte and process it next time this method is called.
*
* @throws IOException if any I/O error occurs.
*/
private void processAndWrite(byte[] block, int dataSize) throws IOException {
mark = 3; // init + reset
int q = 0; // init + reset
int processTillIndex = -1;
if(dataSize == 1024) {
processTillIndex = 1025;
}else {
processTillIndex = 129;
}
while(mark <= processTillIndex) {
if(unprocessedByteInReceivedDataExist == false) {
if(lastCharacterReceivedWasLF) {
data0 = LF;
lastCharacterReceivedWasLF = false; // reset
}else if(lastCharacterReceivedWasCR) {
data0 = CR;
lastCharacterReceivedWasCR = false; // reset
}else {
data0 = block[mark];
mark++;
}
data1 = block[mark];
mark++;
}else {
// there was a pending byte from last block received to be tested against all cases.
data0 = unprocessedByteInLastReceivedBlock;
unprocessedByteInReceivedDataExist = false; // reset
data1 = block[mark];
mark++;
}
if(data0 == CR) {
if(data1 == LF) {
// represent CRLF case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
q = q + 1;
}else {
}
}else if(data1 == CR) {
// represent CRCR case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
tmpReceiveBuffer[q + 2] = CR;
tmpReceiveBuffer[q + 3] = LF;
q = q + 4;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else {
}
}else if(data1 == SUB) {
// represent CRSUB case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
q = q + 1;
}else {
}
}else {
// represent CRX case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
tmpReceiveBuffer[q + 2] = data1;
q = q + 3;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
tmpReceiveBuffer[q + 1] = data1;
q = q + 2;
}else {
}
}
}else if(data0 == LF) {
if(data1 == LF) {
// represent LFLF case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
tmpReceiveBuffer[q + 2] = CR;
tmpReceiveBuffer[q + 3] = LF;
q = q + 4;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else {
}
}else if(data1 == CR) {
// represent LFCR case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
q = q + 1;
}else {
}
}else if(data1 == SUB) {
// represent LFSUB case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
q = q + 2;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
q = q + 1;
}else {
}
}else {
// represent LFX case.
if(osType == SerialComPlatform.OS_WINDOWS) {
tmpReceiveBuffer[q] = CR;
tmpReceiveBuffer[q + 1] = LF;
tmpReceiveBuffer[q + 2] = data1;
q = q + 3;
}else if((osType == SerialComPlatform.OS_MAC_OS_X) || (osType == SerialComPlatform.OS_LINUX)) {
tmpReceiveBuffer[q] = LF;
tmpReceiveBuffer[q + 1] = data1;
q = q + 2;
}else {
}
}
}else if(data0 == SUB) {
if(data1 == LF) {
// represent SUBLF case.
// we need to check that whether next character is CR or LF and then only
// we can decide what to do with this LF. So make this LF as pending and
// let it process with next character in next iteration of this loop.
lastCharacterReceivedWasLF = true;
}else if(data1 == CR) {
// represent SUBCR case.
lastCharacterReceivedWasCR = true;
}else if(data1 == SUB) {
// represent SUBSUB case.
// do nothing, drop/strip this character.
}else {
// represent SUBX case.
tmpReceiveBuffer[q] = data1;
q = q + 1;
}
}else {
if(data1 == LF) {
// represent XLF case.
tmpReceiveBuffer[q] = data0;
q = q + 1;
lastCharacterReceivedWasLF = true;
}else if(data1 == CR) {
// represent XCR case.
tmpReceiveBuffer[q] = data0;
q = q + 1;
lastCharacterReceivedWasCR = true;
}else if(data1 == SUB) {
// represent XSUB case.
tmpReceiveBuffer[q] = data0;
q = q + 1;
}else {
// represent XX case.
tmpReceiveBuffer[q] = data0;
tmpReceiveBuffer[q + 1] = data1;
q = q + 2;
}
}
} // end while loop
// write processed data bytes to file in file system.
outStream.write(tmpReceiveBuffer, 0, q);
if((mark == 1026) || (mark == 130)) {
// indicates last byte in block array could not be processed as one more bytes was needed
// to test against all cases. so save this byte and process it next block of data received.
unprocessedByteInReceivedDataExist = true;
unprocessedByteInLastReceivedBlock = block[mark];
}
}
}