kopia lustrzana https://github.com/SQ9MDD/TTGO-T-Beam-LoRa-APRS
Fix in KISS frame encoding
Fix in ax.25 address portion encoding KISS to TNC2 decodingpull/3/head
Łukasz Nidecki
rodzic
544db5b987
commit
20722282af
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@ -2,7 +2,14 @@
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bool validateTNC2Frame(const String &tnc2FormattedFrame);
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String encode_address_kiss(String tnc2Address, bool isLast);
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String encode_address_ax25(String tnc2Address);
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String decode_address_ax25(const String& ax25Address, bool &isLast);
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bool validateKISSFrame(const String &kissFormattedFrame);
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String encapsulateKISS(const String &ax25Frame);
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String decapsulateKISS(const String& frame);
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/*
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* https://ham.zmailer.org/oh2mqk/aprx/PROTOCOLS
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@ -33,36 +40,46 @@ String encode_kiss(const String& tnc2FormattedFrame) {
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if (validateTNC2Frame(tnc2FormattedFrame)){
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String address = "";
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for (int p=0;p<tnc2FormattedFrame.indexOf(':');p++){
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bool dst_addres_written = false;
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for (int p=0;p<=tnc2FormattedFrame.indexOf(':');p++){
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char currentChar = tnc2FormattedFrame.charAt(p);
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if (currentChar == ':' || currentChar == '>' || currentChar == ','){
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if (currentChar == '>'){
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if (!dst_addres_written && (currentChar == ',' || currentChar == ':')){
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// ax25 frame DST SRC
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// tnc2 frame SRC DST
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ax25Frame = encode_address_kiss(address, currentChar == ':') + ax25Frame;
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ax25Frame = encode_address_ax25(address) + ax25Frame;
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dst_addres_written = true;
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} else {
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ax25Frame += encode_address_kiss(address, currentChar == ':');
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ax25Frame += encode_address_ax25(address);
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}
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address = "";
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} else {
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address += currentChar;
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}
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}
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auto lastAddressChar = (uint8_t)ax25Frame.charAt(ax25Frame.length() - 1);
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ax25Frame.setCharAt(ax25Frame.length() - 1, (char)(lastAddressChar | IS_LAST_ADDRESS_POSITION_MASK));
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ax25Frame += (char)APRS_CONTROL_FIELD;
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ax25Frame += (char)APRS_INFORMATION_FIELD;
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ax25Frame += tnc2FormattedFrame.substring(tnc2FormattedFrame.indexOf(':')+1);
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}
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String kissFrame = encapsulateKISS(ax25Frame);
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return kissFrame;
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}
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String encapsulateKISS(const String &ax25Frame) {
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String kissFrame = "";
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kissFrame += (char)FEND; // start of frame
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kissFrame += (char)CMD_DATA; // TNC0, DATA
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for (int i = 0; i < ax25Frame.length(); ++i) {
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char currentChar = ax25Frame.charAt(i);
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if (currentChar == (char)FEND) {
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kissFrame += FESC;
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kissFrame += TFEND;
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if (currentChar == (char)FEND){
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kissFrame += (char)FESC;
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kissFrame += (char)TFEND;
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} else if (currentChar == (char)FESC){
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kissFrame += FESC;
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kissFrame += TFESC;
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kissFrame += (char)FESC;
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kissFrame += (char)TFESC;
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} else {
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kissFrame += currentChar;
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}
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@ -71,30 +88,107 @@ String encode_kiss(const String& tnc2FormattedFrame) {
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return kissFrame;
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}
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String decapsulateKISS(const String& frame) {
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String ax25Frame = "";
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for (int i = 2; i < frame.length() - 1; ++i) {
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char currentChar = frame.charAt(i);
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if (currentChar == (char)FESC){
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char nextChar = frame.charAt(i+1);
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if (nextChar == (char)TFEND){
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ax25Frame += (char)FEND;
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} else if (nextChar == (char)TFESC){
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ax25Frame += (char)FESC;
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}
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i++;
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} else {
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ax25Frame += currentChar;
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}
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}
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return ax25Frame;
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}
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String decode_kiss(const String& kissFormattedFrame) {
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String TNC2Frame = "";
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if (validateKISSFrame(kissFormattedFrame)){
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String ax25Frame = decapsulateKISS(kissFormattedFrame);
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bool isLast = false;
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String dst_addr = decode_address_ax25(ax25Frame.substring(0, 7), isLast);
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String src_addr = decode_address_ax25(ax25Frame.substring(7, 14), isLast);
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TNC2Frame = src_addr + ">" + dst_addr;
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int digi_info_index = 14;
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while (!isLast && digi_info_index + 7 < ax25Frame.length()){
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String digi_addr = decode_address_ax25(ax25Frame.substring(digi_info_index, digi_info_index+7), isLast);
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TNC2Frame += ',' + digi_addr;
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digi_info_index += 7;
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}
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TNC2Frame += ':';
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TNC2Frame += ax25Frame.substring(digi_info_index + 2);
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}
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return TNC2Frame;
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}
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/**
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* Encode adress in TNC2 monitor format to ax.25/kiss format
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* Encode adress in TNC2 monitor format to ax.25 format
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* @param tnc2Address
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* @param isLast
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* @return
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*/
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String encode_address_kiss(String tnc2Address, bool isLast) {
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String encode_address_ax25(String tnc2Address) {
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if (tnc2Address.indexOf('-') == -1){
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tnc2Address += "-0";
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}
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bool hasBeenDigipited = tnc2Address.indexOf('*') != -1;
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int ssid = tnc2Address.substring(tnc2Address.indexOf('-')+1).toInt();
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int separatorIndex = tnc2Address.indexOf('-');
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int ssid = tnc2Address.substring(separatorIndex + 1).toInt();
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// TODO: SSID should not be > 16
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String kissAddress = "";
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for (int i = 0; i < 6; ++i) {
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if (tnc2Address.length() > i){
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kissAddress += (char)(tnc2Address.charAt(i) << 1);
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char addressChar;
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if (tnc2Address.length() > i && i < separatorIndex){
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addressChar = tnc2Address.charAt(i);
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} else {
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kissAddress += ' ';
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addressChar = ' ';
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}
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kissAddress += (char)(addressChar << 1);
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}
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kissAddress += (char)((ssid << 1) | 0b01100000 | (isLast ? 1 : 0) | (hasBeenDigipited ? 0b10000000 : 0));
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kissAddress += (char)((ssid << 1) | 0b01100000 | (hasBeenDigipited ? HAS_BEEN_DIGIPITED_MASK : 0));
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return kissAddress;
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}
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/**
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* Decode address from ax.25 format to TNC2 monitor format
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* @param ax25Address
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* @return
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*/
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String decode_address_ax25(const String& ax25Address, bool &isLast) {
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String TNCAddress = "";
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for (int i = 0; i < 6; ++i) {
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uint8_t currentCharacter = ax25Address.charAt(i);
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currentCharacter >>= 1;
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if (currentCharacter != ' '){
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TNCAddress += (char)currentCharacter;
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}
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}
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auto ssid_char = (uint8_t) ax25Address.charAt(6);
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bool hasBeenDigipited = ssid_char & HAS_BEEN_DIGIPITED_MASK;
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isLast = ssid_char & IS_LAST_ADDRESS_POSITION_MASK;
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ssid_char >>= 1;
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int ssid = 0b1111 & ssid_char;
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if (ssid){
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TNCAddress += '-';
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TNCAddress += ssid;
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}
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if (hasBeenDigipited){
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TNCAddress += '*';
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}
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return TNCAddress;
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}
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bool validateTNC2Frame(const String &tnc2FormattedFrame) { return (tnc2FormattedFrame.indexOf(':') != -1) && (tnc2FormattedFrame.indexOf('>') != -1); }
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bool validateKISSFrame(const String &kissFormattedFrame) { return kissFormattedFrame.charAt(0) == (char)FEND && kissFormattedFrame.charAt(kissFormattedFrame.length() - 1) == (char)FEND; }
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@ -4,6 +4,9 @@
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#define APRS_CONTROL_FIELD 0x03
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#define APRS_INFORMATION_FIELD 0xf0
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#define HAS_BEEN_DIGIPITED_MASK 0b10000000
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#define IS_LAST_ADDRESS_POSITION_MASK 0b1
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String encode_kiss(const String& tnc2FormattedFrame);
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String decode_kiss(String kissFormattedFrame);
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String decode_kiss(const String& kissFormattedFrame);
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