00001 /*************************************************************************** 00002 ** 00003 ** This file is part of GpCoreTools. 00004 ** 00005 ** This file may be distributed and/or modified under the terms of the 00006 ** GNU General Public License version 2 or 3 as published by the Free 00007 ** Software Foundation and appearing in the file LICENSE.GPL included 00008 ** in the packaging of this file. 00009 ** 00010 ** This file is distributed in the hope that it will be useful, but WITHOUT 00011 ** ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00012 ** FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 00013 ** more details. 00014 ** 00015 ** You should have received a copy of the GNU General Public License 00016 ** along with this program. If not, see <http://www.gnu.org/licenses/>. 00017 ** 00018 ** See http://www.geopsy.org for more information. 00019 ** 00020 ** Created: 2009-06-26 00021 ** Authors: 00022 ** Marc Wathelet 00023 ** Marc Wathelet (LGIT, Grenoble, France) 00024 ** 00025 ***************************************************************************/ 00026 00027 #ifndef MESSAGECLASSIDHEADER_H 00028 #define MESSAGECLASSIDHEADER_H 00029 00030 #include "ByteOrder.h" 00031 #include "Log.h" 00032 #include "FletcherChecksum.h" 00033 #include "GpCoreToolsDLLExport.h" 00034 00035 namespace GpCoreTools { 00036 00037 #pragma pack(1) /* set alignment to 1 byte boundary */ 00038 00039 class GPCORETOOLS_EXPORT MessageClassIdHeader 00040 { 00041 public: 00042 MessageClassIdHeader() {} 00043 inline MessageClassIdHeader(unsigned char msgClass, unsigned char msgId, unsigned int length); 00044 inline MessageClassIdHeader(const MessageClassIdHeader& o); 00045 00046 enum {SynchronizationSize=2, HeaderSize=4, CheckSumSize=2}; 00047 00048 bool isValid() const {return _sync[0]==0xB5 && _sync[1]==0x62;} 00049 inline bool isValid(const FletcherChecksum& cksum, const char * payload=0, 00050 unsigned short payloadLength=0) const; 00051 00052 unsigned char messageClass() const {return _values.messageClass;} 00053 unsigned char messageId() const {return _values.messageId;} 00054 00055 inline void littleEndianValues(); 00056 inline void bigEndianValues(); 00057 00058 unsigned int lengthLittleEndian() const {return ByteOrder::littleEndianToNative(_values.length);} 00059 unsigned int lengthBigEndian() const {return ByteOrder::bigEndianToNative(_values.length);} 00060 00061 const char * header() const {return _bytes;} 00062 protected: 00063 unsigned char _sync[2]; 00064 union { 00065 struct { 00066 unsigned char messageClass; 00067 unsigned char messageId; 00068 unsigned short length; 00069 } _values; 00070 char _bytes[HeaderSize]; 00071 }; 00072 }; 00073 00074 inline MessageClassIdHeader::MessageClassIdHeader(unsigned char msgClass, unsigned char msgId, unsigned int length) 00075 { 00076 _sync[0]=0xB5; 00077 _sync[1]=0x62; 00078 _values.messageClass=msgClass; 00079 _values.messageId=msgId; 00080 _values.length=length; 00081 } 00082 00083 inline MessageClassIdHeader::MessageClassIdHeader(const MessageClassIdHeader& o) 00084 { 00085 _sync[0]=o._sync[0]; 00086 _sync[1]=o._sync[1]; 00087 _values.messageClass=o._values.messageClass; 00088 _values.messageId=o._values.messageId; 00089 _values.length=o._values.length; 00090 } 00091 00092 inline void MessageClassIdHeader::bigEndianValues() 00093 { 00094 #if BYTE_ORDER==LITTLE_ENDIAN 00095 ByteOrder::swap(_bytes[2], _bytes[3]); 00096 #endif 00097 } 00098 00099 inline void MessageClassIdHeader::littleEndianValues() 00100 { 00101 #if BYTE_ORDER==BIG_ENDIAN 00102 ByteOrder::swap(_bytes[2], _bytes[3]); 00103 #endif 00104 } 00105 00106 inline bool MessageClassIdHeader::isValid(const FletcherChecksum& cksum, const char * payload, 00107 unsigned short payloadLength) const 00108 { 00109 FletcherChecksum mycs; 00110 mycs.add(reinterpret_cast<const char *>(header()), HeaderSize); 00111 if(payload) { 00112 mycs.add(payload, payloadLength); 00113 } 00114 if(cksum==mycs) { 00115 return true; 00116 } else { 00117 Log::write(5, "bad checksum 0x%02hhX 0x%02hhX (in message) instead of 0x%02hhX 0x%02hhX (computed)\n", cksum.a(), cksum.b(), mycs.a(), mycs.b()); 00118 return false; 00119 } 00120 } 00121 00122 #pragma pack() // restore original alignment 00123 00124 } // namespace GpCoreTools 00125 00126 #endif // MESSAGECLASSIDHEADER_H
