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/** Functions related to TeleCommand acceptance.
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*
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* @file
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* @author P. LEROY
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*
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* A group of functions to handle TeleCommands parsing.\n
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*
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*/
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#include "tc_acceptance.h"
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unsigned int lookUpTableForCRC[256];
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//**********************
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// GENERAL USE FUNCTIONS
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unsigned int Crc_opt( unsigned char D, unsigned int Chk)
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{
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/** This function generate the CRC for one byte and returns the value of the new syndrome.
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*
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* @param D is the current byte of data.
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* @param Chk is the current syndrom value.
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*
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* @return the value of the new syndrome on two bytes.
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*
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*/
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return(((Chk << 8) & 0xff00)^lookUpTableForCRC [(((Chk >> 8)^D) & 0x00ff)]);
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}
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void initLookUpTableForCRC( void )
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{
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/** This function is used to initiates the look-up table for fast CRC computation.
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*
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* The global table lookUpTableForCRC[256] is initiated.
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*
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*/
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unsigned int i;
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unsigned int tmp;
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for (i=0; i<256; i++)
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{
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tmp = 0;
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if((i & 1) != 0) {
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tmp = tmp ^ 0x1021;
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}
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if((i & 2) != 0) {
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tmp = tmp ^ 0x2042;
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}
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if((i & 4) != 0) {
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tmp = tmp ^ 0x4084;
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}
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if((i & 8) != 0) {
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tmp = tmp ^ 0x8108;
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}
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if((i & 16) != 0) {
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tmp = tmp ^ 0x1231;
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}
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if((i & 32) != 0) {
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tmp = tmp ^ 0x2462;
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}
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if((i & 64) != 0) {
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tmp = tmp ^ 0x48c4;
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}
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if((i & 128) != 0) {
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tmp = tmp ^ 0x9188;
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}
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lookUpTableForCRC[i] = tmp;
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}
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}
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void GetCRCAsTwoBytes(unsigned char* data, unsigned char* crcAsTwoBytes, unsigned int sizeOfData)
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{
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/** This function calculates a two bytes Cyclic Redundancy Code.
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*
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* @param data points to a buffer containing the data on which to compute the CRC.
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* @param crcAsTwoBytes points points to a two bytes buffer in which the CRC is stored.
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* @param sizeOfData is the number of bytes of *data* used to compute the CRC.
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*
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* The specification of the Cyclic Redundancy Code is described in the following document: ECSS-E-70-41-A.
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*
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*/
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unsigned int Chk;
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int j;
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Chk = 0xffff; // reset the syndrom to all ones
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for (j=0; j<sizeOfData; j++) {
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Chk = Crc_opt(data[j], Chk);
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}
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crcAsTwoBytes[0] = (unsigned char) (Chk >> 8);
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crcAsTwoBytes[1] = (unsigned char) (Chk & 0x00ff);
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}
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//*********************
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// ACCEPTANCE FUNCTIONS
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int tc_parser(ccsdsTelecommandPacket_t * TCPacket, unsigned int TC_LEN_RCV, unsigned char *computed_CRC)
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{
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/** This function parses TeleCommands.
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*
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* @param TC points to the TeleCommand that will be parsed.
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* @param TC_LEN_RCV is the received packet length.
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*
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* @return Status code of the parsing.
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*
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* The parsing checks:
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* - process id
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* - category
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* - length: a global check is performed and a per subtype check also
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* - type
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* - subtype
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* - crc
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*
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*/
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int status;
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int status_crc;
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unsigned char pid;
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unsigned char category;
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unsigned int length;
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unsigned char packetType;
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unsigned char packetSubtype;
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unsigned char sid;
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status = CCSDS_TM_VALID;
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// APID check *** APID on 2 bytes
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pid = ((TCPacket->packetID[0] & 0x07)<<4) + ( (TCPacket->packetID[1]>>4) & 0x0f ); // PID = 11 *** 7 bits xxxxx210 7654xxxx
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category = (TCPacket->packetID[1] & 0x0f); // PACKET_CATEGORY = 12 *** 4 bits xxxxxxxx xxxx3210
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length = (TCPacket->packetLength[0] * 256) + TCPacket->packetLength[1];
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packetType = TCPacket->serviceType;
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packetSubtype = TCPacket->serviceSubType;
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sid = TCPacket->sourceID;
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if ( pid != CCSDS_PROCESS_ID ) // CHECK THE PROCESS ID
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{
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status = ILLEGAL_APID;
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}
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if (status == CCSDS_TM_VALID) // CHECK THE CATEGORY
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{
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if ( category != CCSDS_PACKET_CATEGORY )
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{
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status = ILLEGAL_APID;
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}
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}
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if (status == CCSDS_TM_VALID) // CHECK THE PACKET LENGTH FIELD AND THE ACTUAL LENGTH COMPLIANCE
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{
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if (length != TC_LEN_RCV ) {
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status = WRONG_LEN_PKT;
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}
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}
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if (status == CCSDS_TM_VALID) // CHECK THAT THE PACKET DOES NOT EXCEED THE MAX SIZE
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{
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if ( length >= CCSDS_TC_PKT_MAX_SIZE ) {
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status = WRONG_LEN_PKT;
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}
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}
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if (status == CCSDS_TM_VALID) // CHECK THE TYPE
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{
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status = tc_check_type( packetType );
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}
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if (status == CCSDS_TM_VALID) // CHECK THE SUBTYPE
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{
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status = tc_check_subtype( packetSubtype );
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}
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if (status == CCSDS_TM_VALID) // CHECK THE SID
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{
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status = tc_check_sid( sid );
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}
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if (status == CCSDS_TM_VALID) // CHECK THE SUBTYPE AND LENGTH COMPLIANCE
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{
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status = tc_check_length( packetSubtype, length );
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}
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status_crc = tc_check_crc( TCPacket, length, computed_CRC );
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if (status == CCSDS_TM_VALID ) // CHECK CRC
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{
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status = status_crc;
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}
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return status;
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}
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int tc_check_type( unsigned char packetType )
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{
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/** This function checks that the type of a TeleCommand is valid.
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*
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* @param packetType is the type to check.
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*
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* @return Status code CCSDS_TM_VALID or ILL_TYPE.
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*
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*/
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int status;
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if ( (packetType == TC_TYPE_GEN) || (packetType == TC_TYPE_TIME))
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{
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status = CCSDS_TM_VALID;
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}
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else
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{
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status = ILL_TYPE;
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}
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return status;
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}
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int tc_check_subtype( unsigned char packetSubType )
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{
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/** This function checks that the subtype of a TeleCommand is valid.
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*
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* @param packetSubType is the subtype to check.
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*
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* @return Status code CCSDS_TM_VALID or ILL_SUBTYPE.
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*
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*/
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int status;
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if ( (packetSubType == TC_SUBTYPE_RESET)
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|| (packetSubType == TC_SUBTYPE_LOAD_COMM)
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|| (packetSubType == TC_SUBTYPE_LOAD_NORM) || (packetSubType == TC_SUBTYPE_LOAD_BURST)
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|| (packetSubType == TC_SUBTYPE_LOAD_SBM1) || (packetSubType == TC_SUBTYPE_LOAD_SBM2)
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|| (packetSubType == TC_SUBTYPE_DUMP)
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|| (packetSubType == TC_SUBTYPE_ENTER)
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|| (packetSubType == TC_SUBTYPE_UPDT_INFO) || (packetSubType == TC_SUBTYPE_UPDT_TIME)
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|| (packetSubType == TC_SUBTYPE_EN_CAL) || (packetSubType == TC_SUBTYPE_DIS_CAL) )
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{
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status = CCSDS_TM_VALID;
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}
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else
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{
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status = ILL_SUBTYPE;
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}
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return status;
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}
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int tc_check_sid( unsigned char sid )
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{
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/** This function checks that the sid of a TeleCommand is valid.
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*
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* @param sid is the sid to check.
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*
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* @return Status code CCSDS_TM_VALID or CORRUPTED.
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*
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*/
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int status;
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if ( (sid == SID_TC_GROUND)
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|| (sid == SID_TC_MISSION_TIMELINE) || (sid == SID_TC_TC_SEQUENCES) || (sid == SID_TC_RECOVERY_ACTION_CMD)
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|| (sid == SID_TC_BACKUP_MISSION_TIMELINE)
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|| (sid == SID_TC_DIRECT_CMD) || (sid == SID_TC_SPARE_GRD_SRC1) || (sid == SID_TC_SPARE_GRD_SRC2)
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|| (sid == SID_TC_OBCP) || (sid == SID_TC_SYSTEM_CONTROL) || (sid == SID_TC_AOCS)
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|| (sid == SID_TC_RPW_INTERNAL))
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{
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status = CCSDS_TM_VALID;
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}
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else
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{
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status = WRONG_SRC_ID;
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}
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return status;
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}
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int tc_check_length( unsigned char packetSubType, unsigned int length )
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{
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/** This function checks that the subtype and the length are compliant.
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*
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* @param packetSubType is the subtype to check.
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* @param length is the length to check.
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*
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* @return Status code CCSDS_TM_VALID or ILL_TYPE.
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*
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*/
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int status;
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status = LFR_SUCCESSFUL;
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switch(packetSubType)
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{
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case TC_SUBTYPE_RESET:
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if (length!=(TC_LEN_RESET-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_LOAD_COMM:
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if (length!=(TC_LEN_LOAD_COMM-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_LOAD_NORM:
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if (length!=(TC_LEN_LOAD_NORM-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_LOAD_BURST:
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if (length!=(TC_LEN_LOAD_BURST-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_LOAD_SBM1:
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if (length!=(TC_LEN_LOAD_SBM1-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_LOAD_SBM2:
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if (length!=(TC_LEN_LOAD_SBM2-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_DUMP:
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if (length!=(TC_LEN_DUMP-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_ENTER:
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if (length!=(TC_LEN_ENTER-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_UPDT_INFO:
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if (length!=(TC_LEN_UPDT_INFO-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_EN_CAL:
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if (length!=(TC_LEN_EN_CAL-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_DIS_CAL:
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if (length!=(TC_LEN_DIS_CAL-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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case TC_SUBTYPE_UPDT_TIME:
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if (length!=(TC_LEN_UPDT_TIME-CCSDS_TC_TM_PACKET_OFFSET)) {
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status = WRONG_LEN_PKT;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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break;
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default: // if the subtype is not a legal value, return ILL_SUBTYPE
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status = ILL_SUBTYPE;
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break ;
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}
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return status;
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}
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int tc_check_crc( ccsdsTelecommandPacket_t * TCPacket, unsigned int length, unsigned char *computed_CRC )
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{
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/** This function checks the CRC validity of the corresponding TeleCommand packet.
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*
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* @param TCPacket points to the TeleCommand packet to check.
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* @param length is the length of the TC packet.
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*
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* @return Status code CCSDS_TM_VALID or INCOR_CHECKSUM.
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*
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*/
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int status;
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unsigned char * CCSDSContent;
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CCSDSContent = (unsigned char*) TCPacket->packetID;
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GetCRCAsTwoBytes(CCSDSContent, computed_CRC, length + CCSDS_TC_TM_PACKET_OFFSET - 2); // 2 CRC bytes removed from the calculation of the CRC
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if (computed_CRC[0] != CCSDSContent[length + CCSDS_TC_TM_PACKET_OFFSET -2]) {
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status = INCOR_CHECKSUM;
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}
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else if (computed_CRC[1] != CCSDSContent[length + CCSDS_TC_TM_PACKET_OFFSET -1]) {
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status = INCOR_CHECKSUM;
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}
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else {
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status = CCSDS_TM_VALID;
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}
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return status;
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}
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