sys: shell: mersenne: adapt to xtimer

sys/shell/commands/sc_mersenne.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 Freie Universität Berlin
+ *               2015 Kaspar Schleiser <kaspar@schleiser.de>
  *
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License v2.1. See the file LICENSE in the top level
@@ -14,7 +15,7 @@
  * @brief       Shell commands for mersenne twister
  *
  * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
- *
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
  * @}
  */
 
@@ -23,7 +24,10 @@
 #include <string.h>
 #include <inttypes.h>
 
-#include "hwtimer.h"
+#ifdef MODULE_XTIMER
+#include "xtimer.h"
+#endif
+
 #include "random.h"
 
 int _mersenne_init(int argc, char **argv)
@@ -31,8 +35,13 @@ int _mersenne_init(int argc, char **argv)
     int initval;
 
     if (argc == 1) {
-        initval = hwtimer_now();
+#ifdef MODULE_XTIMER
+        initval = xtimer_now();
         printf("PRNG initialized to current time: %d\n", initval);
+#else
+        (void)initval;
+        printf("xtimer module not compiled in, can't initialize by time.\n");
+#endif
     }
     else {
         initval = atoi(argv[1]);