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--- projects:high_altitude_slug:software:protocol [2006/07/08 10:44] – (old revision restored) 127.0.0.1
+++ projects:high_altitude_slug:software:protocol [2008/07/19 23:33] (current) – external edit 127.0.0.1
@@ Line 6: / Line 6: @@
 ===== Commands =====
-We have a 16 unsigned integer for commands:
+We have a 16 bit unsigned integer for commands:
 ==== Human messages (0 - 9) ====
-  * [0 - 9] CMD_MESSAGE_[0-9] string - Human messages. 0 is lowest priority, 9 is highest.
+  * [0 - 9] CMD_MESSAGE_[0-9] char - Human messages. 0 is lowest priority, 9 is highest.
-==== All processes (10 - 4999) ====
+==== All processes ====
+  * 10 CMD_ERROR int - Error occured
+==== GPS reader ====
+  * 5000 CMD_GPS_DATA struct gps_data - GPS data
-==== GPS reader (5000 - 5999) ====
+==== Thermopile reader ====
+  * 5500 CMD_THERMOPILE_DATA struct thermopile_data - Thermopile data
 ==== Flight management (6000 - 6999) ====
+  * 6000 CMD_STATUS int - Status of flight has changed, one of:
+    * 0 - Flight not started
+    * 1 - Ascent
+    * 2 - Descent
+    * 3 - Descent with parachute released
+    * 4 - Landed
+  * 6001 CMD_PARACHUTE bool - Parachute released if size > 0, else a request to release
+  * 6003 CMD_CUTDOWN bool - Glider has been cutdown if size > 0, else a request to release
+  * 6005 CMD_DESIRED_HEADING double - The desired heading calculated by the flight management.
+  * 6006 CMD_ALT_DROP_POSITION int - 0 - not in altitude drop, 1-4, position from north clockwise
+  * 6007 CMD_FINAL_WAYPOINT waypoint_t - The final waypoint, generally the launch point
-==== Roll control (7000 - 7999) ====
+==== Roll control ====
-  * 7000 CMD_DESIRED_HEADING double - The desired heading calculated by the flight management.
+==== Pitch control ====
-==== Pitch control (8000 - 8999) ====
+==== Configuration ====
+See configuration files for descriptions and categorisation.
-===== Client Library Functions =====
+  * 10000 CMD_CONFIG_...
-==== client_init ====
+to be finished
-The ''client_init'' function should be called before any other client related functions and connects to ''serverAddr'' (probably ''localhost'') on port ''port''. Both of these values should be #defined in ''config.h'' as SERVER and PORT respectively. The function is prototyped as:
-  int client_init (char *serverAddr, unsigned short port);
-in client.h
-On success ''client_init'' function returns the socket file descriptor of the server that it has connected to which should be passed to all client-related functions. On failure the function returns -1 and makes a note in the client error log.
-==== client_recv_packet ====
-The ''client_recv_packet'' function is used to read packets of data from the server. It reads a single packet of data from ''serverFD'' (the servers network file descriptor returned by ''client_init'') and then places the packet into ''packet'' which should be a pointer to a ''client_packet'' structure. It is prototyped as:
-  int client_recv_packet (unsigned short serverFD, struct client_packet *packet);
-in client.h
-The ''client_recv_packet'' function will automatically perform byte-conversions on ''packet->command'' and ''packet->len'' using the ''ntohs'' function.
-First of all the function will read 4 bytes of data from the ''serverFD'', convert them to the host byte order and then use the ''packet->len'' variable to work out the length of the data segment of the packet. Next, ''malloc'' is used to allocate enough memory to store the data segment of the packet and the null byte (''packet->len + 1''), before going onto reading the data segment into the newly allocated string and then setting the last byte to ''\0''.
-**Please note the the data segment of the packet (''packet->data'') is made up of memory allocated off of the heap, and so needs to be ''free()'''ed when no longer needed to prevent a memory leak!**
-On success this function will return 0 while on failure this function will return -1 and will make a note in the error log about exactly what went wrong.
-==== client_recv_packets ====
-The ''client_recv_packets'' function is very similar to the ''client_recv_packet'' function, except that it will return all of the packets in the buffer and will allocate memory as required. Unlike ''client_recv_packet'' the ''client_recv_packets'' function is non-blocking and will return if there is nothing in the buffer. It is prototyped as:
-  struct client_packet *client_recv_packets(unsigned short serverFD, int *npackets);
-in client.h
-Since this function makes calls to the ''client_recv_packet'' function to actually read the data from the buffer it also performs byte-conversions on ''command'' and ''len'' member variables.
-On success this function returns a pointer to a ''client_packet'' structure and places the number of items read from the server into ''npackes''. On failure, ''NULL'' is returned and ''npackets'' is set to 0.
-==== client_send_packet ====
-The ''client_send_packet'' function should be used to send a packet of information to the server (aka the 'party line'). It sends ''packet'' to ''serverFD'' (which is the servers file descriptor) and is prototyped as:
-  int client_send_packet (unsigned short serverFD, struct client_packet *packet);
-in client.h
-Like the ''client_recv_packet'' function the ''client_send_packet'' function will automatically perform byte-conversions on both ''packet->command'' and ''packet->len'' to convert them to the network byte order using ''htons'' function.
-On success the function will return 0 otherwise, on failure, will return -1 and make a note in the error log about what went  wrong.
-==== client_close ====
-The ''client_close'' function simply closes ''serverFD'' by calling the ''close'' function (which it is no more than a wrapper over) and is prototyped as:
-  void client_close (unsigned short serverFD)
-in client.h
-''client_close'' should be called when the connection to the server ('party line') is no longer needed.
-===== Example Application =====
-Here is a simple application that demonstrates the use of these functions. The program basically forks (creates a copy of) itself. Both of the processes then connect to the server, once a connection has been established the child process will then wait for 0.25 seconds, giving the parent process time to send two packets of data to the party line at which point the parent process then exits. After the child processes 0.25 second wait has elapsed it will call the ''client_recv_packets'' function to read all of the packets from the server (which should be the two that the parent sent) and then prints them out to the terminal before ''free()''ing all of the memory allocated by the ''client_recv_packets'' function and exiting.