source: ntrip/trunk/BNC/GPSS/gpssDecoder.cpp@ 1435

Last change on this file since 1435 was 1435, checked in by mervart, 15 years ago

* empty log message *
File size: 4.0 KB
Line 
1\
2/* -------------------------------------------------------------------------
3 * BKG NTRIP Client
4 * -------------------------------------------------------------------------
5 *
6 * Class: gpssDecoder
7 *
8 * Purpose: Decode Data in GPSS Format
9 *
10 * Author: L. Mervart
11 *
12 * Created: 20-Dec-2008
13 *
14 * Changes:
15 *
16 * -----------------------------------------------------------------------*/
17
18#include <iostream>
19
20#include "gpssDecoder.h"
21#include "bncapp.h"
22
23#define MODE_SEARCH 0
24#define MODE_TYPE 1
25#define MODE_EPOCH 2
26#define MODE_EPOCH_BODY 3
27#define MODE_EPOCH_CRC 4
28#define MODE_EPOCH_ETX 5
29#define MODE_EPH 6
30#define MODE_EPH_BODY 7
31#define MODE_EPH_CRC 8
32#define MODE_EPH_ETX 9
33
34using namespace std;
35
36typedef struct epochHeader {
37 double t_epoch;
38 int n_svs;
39} EPOCHHEADER;
40
41// Cyclic Redundancy Check
42////////////////////////////////////////////////////////////////////////////
43unsigned short cal_crc(unsigned char *buf, int num) {
44 unsigned short polynomial = 0x8408;
45 unsigned short crc = 0;
46 int i;
47 while ( num-- ) {
48 crc = ( crc & 0xFF00 ) | ( *buf++^( crc & 0x00FF ) );
49 for( i=0; i<8; i++ ){
50 if( crc & 0x0001 ){
51 crc >>= 1;
52 crc ^= polynomial;
53 }
54 else{
55 crc >>= 1;
56 }
57 }
58 }
59 return (crc);
60}
61
62// Constructor
63////////////////////////////////////////////////////////////////////////////
64gpssDecoder::gpssDecoder() : GPSDecoder() {
65 _mode = MODE_SEARCH;
66
67 connect(this, SIGNAL(newGPSEph(gpsephemeris*)),
68 (bncApp*) qApp, SLOT(slotNewGPSEph(gpsephemeris*)));
69}
70
71// Destructor
72////////////////////////////////////////////////////////////////////////////
73gpssDecoder::~gpssDecoder() {
74}
75
76//
77////////////////////////////////////////////////////////////////////////////
78t_irc gpssDecoder::Decode(char* data, int dataLen, vector<string>& errmsg) {
79
80 errmsg.clear();
81
82 _buffer += QByteArray(data, dataLen);
83
84 cout << "Decode: buffer length = " << _buffer.length() << endl;
85
86 int iBeg;
87 while ( (iBeg = _buffer.indexOf(0x02)) != -1) {
88 _buffer = _buffer.mid(iBeg);
89
90 int recordSize;
91 int crc;
92
93 // Observations
94 // ------------
95 if (char(_buffer[1]) == 0x00) {
96
97 int reqLength = 2 + sizeof(recordSize) + sizeof(EPOCHHEADER);
98
99 if (_buffer.length() >= reqLength) {
100 EPOCHHEADER epochHdr;
101 memcpy(&epochHdr, _buffer.data() + 2 + sizeof(recordSize),
102 sizeof(epochHdr));
103
104 reqLength += epochHdr.n_svs * sizeof(t_obsInternal) + sizeof(crc) + 1;
105
106 if (_buffer.length() >= reqLength) {
107
108 int checkLen = 2 + sizeof(recordSize) + sizeof(EPOCHHEADER) +
109 epochHdr.n_svs * sizeof(t_obsInternal);
110 memcpy(&crc, _buffer.data() + checkLen, sizeof(crc));
111 int crdCal = cal_crc((unsigned char*) _buffer.data(), checkLen);
112
113 cout << "Obs: " << crc << " " << crdCal << endl;
114
115 for (int is = 0; is < epochHdr.n_svs; is++) {
116 t_obs* obs = new t_obs();
117 memcpy(&(obs->_o), _buffer.data() + 2 + sizeof(recordSize) +
118 sizeof(epochHdr) + is * sizeof(t_obsInternal),
119 sizeof(t_obsInternal));
120 _obsList.push_back(obs);
121 }
122 }
123 }
124 _buffer = _buffer.mid(reqLength);
125 }
126
127 // Ephemeris
128 // ---------
129 else if (char(_buffer[1]) == 0x01) {
130 int reqLength = 2 + sizeof(recordSize) + sizeof(gpsephemeris) +
131 sizeof(crc) + 1;
132
133 if (_buffer.length() >= reqLength) {
134
135 int checkLen = 2 + sizeof(recordSize) + sizeof(gpsephemeris);
136 memcpy(&crc, _buffer.data() + checkLen, sizeof(crc));
137 int crdCal = cal_crc((unsigned char*) _buffer.data(), checkLen);
138
139 cout << "Eph: " << crc << " " << crdCal << endl;
140
141 gpsephemeris* gpsEph = new gpsephemeris;
142 memcpy(gpsEph, _buffer.data() + 2 + sizeof(recordSize),
143 sizeof(gpsephemeris));
144 emit newGPSEph(gpsEph);
145 }
146 _buffer = _buffer.mid(reqLength);
147 }
148
149 else {
150 _buffer == _buffer.mid(1);
151 }
152 }
153
154 return success;
155}
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