tests: add test_vtimer_msg_diff

This test sets three timers and renews them periodically, showing the
difference they accumulate.

tests/test_vtimer_msg_diff/Makefile

@@ -0,0 +1,6 @@
+export PROJECT = test_vtimer_msg_diff
+include ../Makefile.tests_common
+
+USEMODULE += vtimer
+
+include $(RIOTBASE)/Makefile.include

tests/test_vtimer_msg_diff/main.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2013 INRIA
+ * Copyright (C) 2014 Kaspar Schleiser
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup tests
+ * @{
+ *
+ * @file
+ * @brief Thread test application
+ *
+ * @author      Oliver Hahm <oliver.hahm@inria.fr>
+ * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+#include <time.h>
+
+#include "vtimer.h"
+#include "thread.h"
+#include "msg.h"
+
+#define MAXCOUNT 20
+#define MAXDIFF 500
+
+char timer_stack[KERNEL_CONF_STACKSIZE_PRINTF];
+
+struct timer_msg {
+    vtimer_t timer;
+    timex_t interval;
+    char *msg;
+    timex_t start;
+    int count;
+};
+
+timex_t now;
+
+struct timer_msg msg_a = { .interval = { .seconds = 2, .microseconds = 0}, .msg = "T1", .start={0}, .count=0 };
+struct timer_msg msg_b = { .interval = { .seconds = 3, .microseconds = 0}, .msg = "T2", .start={0}, .count=0 };
+struct timer_msg msg_c = { .interval = { .seconds = 5, .microseconds = 0}, .msg = "T3", .start={0}, .count=0 };
+
+void timer_thread(void)
+{
+    printf("This is thread %d\n", thread_getpid());
+
+    msg_t msgq[16];
+    msg_init_queue(msgq, sizeof msgq);
+
+    while (1) {
+        msg_t m;
+        msg_receive(&m);
+        struct timer_msg *tmsg = (struct timer_msg *) m.content.ptr;
+
+        vtimer_now(&now);
+
+        if (tmsg->start.seconds==0 && tmsg->start.microseconds == 0) {
+            printf("Initializing \"%s\".\n", tmsg->msg);
+            tmsg->start = now;
+        } else {
+            tmsg->count++;
+        }
+
+        uint64_t should = timex_uint64(tmsg->interval)*tmsg->count+timex_uint64(tmsg->start);
+        int64_t diff = should - timex_uint64(now);
+
+        printf("now=%02" PRIu32 ":%02" PRIu32 " -> every %" PRIu32 ".%" PRIu32 "s: %s diff=%" PRId64 "\n",
+               now.seconds,
+               now.microseconds,
+               tmsg->interval.seconds,
+               tmsg->interval.microseconds,
+               tmsg->msg, diff);
+
+        if (diff > MAXDIFF || diff < -MAXDIFF) {
+            printf("WARNING: timer difference %" PRId64 "us exceeds MAXDIFF(%d)!\n", diff, MAXDIFF);
+        }
+
+        if (vtimer_set_msg(&tmsg->timer, tmsg->interval, thread_getpid(), tmsg) != 0) {
+            puts("something went wrong setting a timer");
+        }
+
+        if (tmsg->count >= MAXCOUNT) {
+            printf("Maximum count reached. (%d) Exiting.\n", MAXCOUNT);
+            break;
+        }
+    }
+}
+
+int main(void)
+{
+    msg_t m;
+    int pid = thread_create(
+                  timer_stack,
+                  sizeof timer_stack,
+                  PRIORITY_MAIN - 1,
+                  CREATE_STACKTEST,
+                  timer_thread,
+                  "timer");
+
+    puts("sending 1st msg");
+    m.content.ptr = (char *) &msg_a;
+    msg_send(&m, pid, false);
+
+    puts("sending 2nd msg");
+    m.content.ptr = (char *) &msg_b;
+    msg_send(&m, pid, false);
+    
+    puts("sending 3nd msg");
+    m.content.ptr = (char *) &msg_c;
+    msg_send(&m, pid, false);
+
+    return 0;
+}