Add comments at the beginning of client and server files

packet-exchange/src/client.c

-#define _GNU_SOURCE
-
+/*
+ * Real time packet sending thread
+ *
+ * Bash options:
+ *
+ *  -a          Run the real time thread on CPU1
+ *  -i USEC     Wake up the real time thread every USEC microseconds
+ *  -l N        Wake up the real time thread N times
+ *  -p PRIO     Run the real time thread at priority PRIO
+ *  -r USEC     Refresh the non real time main thread every USEC microseconds
+ *
+ */
 #include <errno.h>
 #include <error.h>
 #include <pthread.h>
@@ -13,6 +23,8 @@
 
 #include "send_packet.h"
 
+#define _GNU_SOURCE
+
 #define CLOCK_ID CLOCK_MONOTONIC
 #define NSEC_PER_SEC UINT64_C(1000000000)
 
@@ -46,7 +58,7 @@ static void *packet_sending_thread(void *p) {
   thread_param_t *param = (thread_param_t *)p;
   cpu_set_t mask;
 
-  if(param->enable_affinity) {
+  if (param->enable_affinity) {
     // Set thread CPU affinity
     CPU_ZERO(&mask);
     CPU_SET(1, &mask);

packet-exchange/src/server.c

-#define _GNU_SOURCE
+/*
+ * Real time packet receiving thread
+ *
+ * Bash options:
+ *
+ *  -a          Run the real time thread on CPU1
+ *  -p PRIO     Run the real time thread at priority PRIO
+ *  -r USEC     Refresh the non real time main thread every USEC microseconds
+ *
+ */
 
 #include <arpa/inet.h>
 #include <errno.h>
@@ -17,6 +26,8 @@
 #include <time.h>
 #include <unistd.h>
 
+#define _GNU_SOURCE
+
 #define NSEC_PER_SEC UINT64_C(1000000000)
 
 #define SERVER_PORT "50000"
@@ -69,7 +80,7 @@ static void *packet_receiving_thread(void *p) {
   stats->min_interval = UINT64_MAX;
   stats->max_interval = 0;
 
-  if(param->enable_affinity) {
+  if (param->enable_affinity) {
     // Set thread CPU affinity
     CPU_ZERO(&mask);
     CPU_SET(1, &mask);