CTX_scp.c File Reference

CTX service callback ("spacecraft" specific). More...

#include <string.h>
#include <PBS/MBA.h>
#include <MSG/MSG_pubdefs.h>
#include <CCSDS/CCSDS_pkt.h>
#include <CTDB/CTDB_config.h>
#include <CTDB/CTDB_bc.h>
#include <ITC/ITC_apidefs.h>
#include <ITC/ITC_drvdefs.h>
#include <ITC/ITC_pubdefs.h>
#include <ITC/ITC_msgs.h>
#include <CTS/CTS_pubdefs.h>
#include <CTS/CTS_msgs.h>
#include <CTS_prvdefs.h>

Functions
static void	CTX_freePacket (void *pkt, void *prm)
	Free a queue item.
unsigned int	CTX_createService (ITC_TaskID tid, unsigned int nim, ITC_cb_Memory *rtn, void *prm)
	Initialize an CTX service control block.
unsigned int	CTX_sendCmd (void *prm, const ITC_QueueItem *qitem, void *pay, unsigned int len)
	Callback for service task sending telecommands to LAT.

---

Detailed Description

CTX service callback ("spacecraft" specific).

CVS $Id: CTX_scp.c,v 1.6 2011/03/28 23:55:14 apw Exp $

Author:

A.P.Waite

---

Function Documentation

unsigned int CTX_createService	(	ITC_TaskID	tid,
		unsigned int	nim,
		ITC_cb_Memory *	rtn,
		void *	prm
	)

Initialize an CTX service control block.

Parameters:

	tid	(in) ITC task ID for this service
	nim	(in) Mask of ITC nodes served by this service (not implemented)
	rtn	(in) Memory allocator for diagnostic stream
	prm	(in) Memory allocator for diagnostic stream - parameter

Return values:

	CTS_SUCCESS	Success
	CTS_QCREATE	Cannot create queue

CTX_createService() creates and intializes an CTX service control block

References _CTS_Control::cnt, CTS_ccb, CTS_CTL_INITIALIZED, CTS_ctl_states, _CTS_Control::ctx, CTX_createQ(), CTX_deleteQ(), CTX_sendCmd(), CTX_SVC_INITIALIZED, _CTS_Control::mtx, and _CTS_Control::state.

Referenced by CTS_configure().

static void CTX_freePacket	(	void *	pkt,
		void *	prm
	)			[static]

Free a queue item.

Parameters:

	pkt	Packet to free (unused)
	prm	User context parameter (queue item)

Referenced by CTX_sendCmd().

unsigned int CTX_sendCmd	(	void *	prm,
		const ITC_QueueItem *	qitem,
		void *	pay,
		unsigned int	len
	)

Callback for service task sending telecommands to LAT.

Parameters:

	prm	(in) User context parameter
	qitem	(in) Queue item
	pay	(in) Queue item payload pointer
	len	(in) Queue item payload length

CTX_sendCmd() reads one ITC queue, ITC_QID_CMD, looking for commands that spacecraft side applications want to send to the LAT. Commands are expected to be valid CCSDS packets contained in ITC protocol (though CTX_sendCmd() will check CCSDS integrity, see below).

Warning:

Byte ordering:

• CTX_sendCmd() requires that incoming packets have their CCSDS header in machine-local byte order.
• Because the CTDB driver expects the packet in network (big-endian) order, CTX_sendCmd() will perform any necessary byte-swapping on CCSDS headers and checksum fields only. (A service layer routine such as CTX_sendCmd() has no basis to perform CCSDS packet payload byte-swapping).

If any of the following conditions is true, the packet is dropped:

• Packet size is less than the sum of: a telecommand primary header, a telecommand secondary header, a telecommand checksum.
• Packet length is greater than a maximum size defined by CTDB_CONFIG_PKT_SIZE_CMD_RX.
• The packet is an odd number of bytes.
• The packet is not CCSDS version 1.
• Packet secondary header bit is clear.
• Packet command bit is clear.
• APID is outside the allowed range for telecommands from spacecraft to LAT.

For packets passing these tests, CTX_sendCmd() will:

• Insert the CCSDS header sequence number (maintained per APID).
• Calculate and insert the checksum.
• Do any necessary byte-swapping on headers and checksums.

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Return values:

	CTX_BADQUEU	CTX does not accept packets this queue
	CTX_CMDAPID	Telecommand APID not in valid range
	CTX_CMDBITC	Telecommand bit clear in telecommand packet
	CTX_CMDEVEN	Telecommand packet length not an even number of bytes
	CTX_CMDHEAD	Telecommand packet header verification failed
	CTX_CMDLEN	Telecommand packet length not in valid range
	CTX_CMDQUEU	Error queueing telecommmand packet to CTDB driver
	ITC_FORWARD	Service completed successfully, do not free packet

References _CTX_Service::cmd, CTS_getDevice(), and CTX_freePacket().

Referenced by CTX_createService().