[1429] | 1 | \
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[1310] | 2 | /* -------------------------------------------------------------------------
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| 3 | * BKG NTRIP Client
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| 4 | * -------------------------------------------------------------------------
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| 5 | *
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| 6 | * Class: gpssDecoder
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| 7 | *
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| 8 | * Purpose: Decode Data in GPSS Format
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| 9 | *
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| 10 | * Author: L. Mervart
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| 11 | *
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| 12 | * Created: 20-Dec-2008
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| 13 | *
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| 14 | * Changes:
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| 15 | *
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| 16 | * -----------------------------------------------------------------------*/
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| 17 |
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| 18 | #include "gpssDecoder.h"
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[1314] | 19 | #include "bncapp.h"
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[1310] | 20 |
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| 21 | using namespace std;
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| 22 |
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[1311] | 23 | typedef struct epochHeader {
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| 24 | double t_epoch;
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| 25 | int n_svs;
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| 26 | } EPOCHHEADER;
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| 27 |
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[1434] | 28 | // Cyclic Redundancy Check
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| 29 | ////////////////////////////////////////////////////////////////////////////
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[1435] | 30 | unsigned short cal_crc(unsigned char *buf, int num) {
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[1434] | 31 | unsigned short polynomial = 0x8408;
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| 32 | unsigned short crc = 0;
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| 33 | int i;
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| 34 | while ( num-- ) {
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| 35 | crc = ( crc & 0xFF00 ) | ( *buf++^( crc & 0x00FF ) );
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| 36 | for( i=0; i<8; i++ ){
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| 37 | if( crc & 0x0001 ){
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| 38 | crc >>= 1;
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| 39 | crc ^= polynomial;
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| 40 | }
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| 41 | else{
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| 42 | crc >>= 1;
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| 43 | }
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| 44 | }
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| 45 | }
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| 46 | return (crc);
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| 47 | }
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| 48 |
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[1310] | 49 | // Constructor
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| 50 | ////////////////////////////////////////////////////////////////////////////
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| 51 | gpssDecoder::gpssDecoder() : GPSDecoder() {
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[1314] | 52 | connect(this, SIGNAL(newGPSEph(gpsephemeris*)),
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[2545] | 53 | (bncApp*) qApp, SLOT(slotNewGPSEph(gpsephemeris*)),
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| 54 | Qt::DirectConnection);
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[1310] | 55 | }
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| 56 |
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| 57 | // Destructor
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| 58 | ////////////////////////////////////////////////////////////////////////////
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| 59 | gpssDecoder::~gpssDecoder() {
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| 60 | }
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| 61 |
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| 62 | //
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| 63 | ////////////////////////////////////////////////////////////////////////////
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[1311] | 64 | t_irc gpssDecoder::Decode(char* data, int dataLen, vector<string>& errmsg) {
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| 65 |
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[1310] | 66 | errmsg.clear();
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| 67 |
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[1429] | 68 | _buffer += QByteArray(data, dataLen);
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[1311] | 69 |
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[1438] | 70 | bool obsFound = false;
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| 71 | bool ephFound = false;
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[1429] | 72 | int iBeg;
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| 73 | while ( (iBeg = _buffer.indexOf(0x02)) != -1) {
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| 74 | _buffer = _buffer.mid(iBeg);
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[1311] | 75 |
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[1429] | 76 | int recordSize;
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[1430] | 77 | int crc;
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[1429] | 78 |
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| 79 | // Observations
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| 80 | // ------------
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[1438] | 81 | if (_buffer.length() > 0 && char(_buffer[1]) == 0x00) {
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[1431] | 82 |
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| 83 | int reqLength = 2 + sizeof(recordSize) + sizeof(EPOCHHEADER);
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| 84 |
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| 85 | if (_buffer.length() >= reqLength) {
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| 86 | EPOCHHEADER epochHdr;
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[1429] | 87 | memcpy(&epochHdr, _buffer.data() + 2 + sizeof(recordSize),
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| 88 | sizeof(epochHdr));
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[1431] | 89 |
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| 90 | reqLength += epochHdr.n_svs * sizeof(t_obsInternal) + sizeof(crc) + 1;
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[1311] | 91 |
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[1430] | 92 | if (_buffer.length() >= reqLength) {
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[1434] | 93 |
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| 94 | int checkLen = 2 + sizeof(recordSize) + sizeof(EPOCHHEADER) +
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| 95 | epochHdr.n_svs * sizeof(t_obsInternal);
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| 96 | memcpy(&crc, _buffer.data() + checkLen, sizeof(crc));
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[1436] | 97 | int crcCal = cal_crc((unsigned char*) _buffer.data(), checkLen);
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[1434] | 98 |
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[1436] | 99 | if (crc == crcCal) {
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| 100 | for (int is = 0; is < epochHdr.n_svs; is++) {
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[1438] | 101 | obsFound = true;
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[1436] | 102 | t_obs* obs = new t_obs();
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| 103 | memcpy(&(obs->_o), _buffer.data() + 2 + sizeof(recordSize) +
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| 104 | sizeof(epochHdr) + is * sizeof(t_obsInternal),
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| 105 | sizeof(t_obsInternal));
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| 106 | _obsList.push_back(obs);
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| 107 | }
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[1429] | 108 | }
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| 109 | }
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[1425] | 110 | }
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[1433] | 111 | _buffer = _buffer.mid(reqLength);
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[1425] | 112 | }
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[1311] | 113 |
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[1429] | 114 | // Ephemeris
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| 115 | // ---------
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[1438] | 116 | else if (_buffer.length() > 0 && char(_buffer[1]) == 0x01) {
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[1430] | 117 | int reqLength = 2 + sizeof(recordSize) + sizeof(gpsephemeris) +
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[1438] | 118 | sizeof(crc) + 1;
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[1431] | 119 |
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[1434] | 120 | if (_buffer.length() >= reqLength) {
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[1431] | 121 |
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[1434] | 122 | int checkLen = 2 + sizeof(recordSize) + sizeof(gpsephemeris);
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| 123 | memcpy(&crc, _buffer.data() + checkLen, sizeof(crc));
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[1436] | 124 | int crcCal = cal_crc((unsigned char*) _buffer.data(), checkLen);
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[1434] | 125 |
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[1436] | 126 | if (crc == crcCal) {
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[1438] | 127 | ephFound = true;
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[1436] | 128 | gpsephemeris* gpsEph = new gpsephemeris;
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| 129 | memcpy(gpsEph, _buffer.data() + 2 + sizeof(recordSize),
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| 130 | sizeof(gpsephemeris));
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| 131 | emit newGPSEph(gpsEph);
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| 132 | }
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[1426] | 133 | }
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[1433] | 134 | _buffer = _buffer.mid(reqLength);
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[1425] | 135 | }
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[1311] | 136 |
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[1425] | 137 | else {
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[1429] | 138 | _buffer == _buffer.mid(1);
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[1311] | 139 | }
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[1312] | 140 | }
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[1311] | 141 |
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[1438] | 142 | if (obsFound || ephFound) {
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| 143 | return success;
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| 144 | }
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| 145 | else {
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| 146 | return failure;
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| 147 | }
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[1310] | 148 | }
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