Import of the contiki-2.x development code from the SICS internal CVS server

doc/example-program.c

@@ -0,0 +1,89 @@
+/*
+ * This file contains an example of how a Contiki program looks.
+ *
+ * The program opens a UDP broadcast connection and sends one packet
+ * every second.
+ */
+
+#include "contiki.h"
+#include "contiki-net.h"
+
+/*
+ * All Contiki programs must have a process, and we declare it here.
+ */
+PROCESS(example_program_process, "Example process");
+
+/*
+ * To make the program send a packet once every second, we use an
+ * event timer (etimer).
+ */
+static struct etimer timer;
+
+/*---------------------------------------------------------------------------*/
+/*
+ * Here we implement the process. The process is run whenever an event
+ * occurs, and the parameters "ev" and "data" will we set to the event
+ * type and any data that may be passed along with the event.
+ */
+PROCESS_THREAD(example_program_process, ev, data)
+{
+  /*
+   * Declare the UDP connection. Note that this *MUST* be declared
+   * static, or otherwise the contents may be destroyed. The reason
+   * for this is that the process runs as a protothread, and
+   * protothreads do not support stack variables.
+   */
+  static struct uip_udp_conn *c;
+  
+  /*
+   * A process thread starts with PROCESS_BEGIN() and ends with
+   * PROCESS_END().
+   */  
+  PROCESS_BEGIN();
+
+  /*
+   * We create the UDP connection to port 4321. We don't want to
+   * attach any special data to the connection, so we pass it a NULL
+   * parameter.
+   */
+  c = udp_broadcast_new(HTONS(4321), NULL);
+  
+  /*
+   * Loop for ever.
+   */
+  while(1) {
+
+    /*
+     * We set a timer that wakes us up once every second. 
+     */
+    etimer_set(&timer, CLOCK_SECOND);
+    PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&timer));
+
+    /*
+     * Now, this is a the tricky bit: in order for us to send a UDP
+     * packet, we must call upon the uIP TCP/IP stack process to call
+     * us. (uIP works under the Hollywood principle: "Don't call us,
+     * we'll call you".) We use the function tcpip_poll_udp() to tell
+     * uIP to call us, and then we wait for the uIP event to come.
+     */
+    tcpip_poll_udp(c);
+    PROCESS_WAIT_EVENT_UNTIL(ev == tcpip_event);
+
+    /*
+     * We can now send our packet.
+     */
+    uip_send("Hello", 5);
+
+    /*
+     * We're done now, so we'll just loop again.
+     */
+  }
+
+  /*
+   * The process ends here. Even though our program sits is a while(1)
+   * loop, we must put the PROCESS_END() at the end of the process, or
+   * else the program won't compile.
+   */
+  PROCESS_END();
+}
+/*---------------------------------------------------------------------------*/