From dd0f707410eea7f843df4a7ff99c41d6ca00d65a Mon Sep 17 00:00:00 2001
From: Antoine Drouin <poinix@gmail.com>
Date: Mon, 14 Jun 2010 16:34:42 +0000
Subject: [PATCH] support for periodic event for overo ( using a high priority
 forked process and signals )

---
 sw/airborne/fms/fms_periodic.c | 108 +++++++++++++++++++++++++++++++++
 sw/airborne/fms/fms_periodic.h |  31 ++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 sw/airborne/fms/fms_periodic.c
 create mode 100644 sw/airborne/fms/fms_periodic.h

diff --git a/sw/airborne/fms/fms_periodic.c b/sw/airborne/fms/fms_periodic.c
new file mode 100644
index 0000000000..d20fc18843
--- /dev/null
+++ b/sw/airborne/fms/fms_periodic.c
@@ -0,0 +1,108 @@
+/*
+ * $Id$
+ *  
+ * Copyright (C) 2010 Antoine Drouin <poinix@gmail.com>
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA. 
+ *
+ */
+
+#include "fms_periodic.h"
+
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <time.h>
+
+#include "fms_debug.h"
+
+static void fms_periodic_run(void);
+static void fms_periodic_delete(void);
+
+struct FmsPeriodic {
+  pid_t ap_pid;
+};
+
+
+int fms_periodic_init(void(*periodic_handler)(int) ) {
+  
+  pid_t my_pid = fork();
+  if (my_pid == -1) {
+    TRACE(TRACE_ERROR,"fms_periodic : unable to fork : %s (%d)\n", strerror(errno), errno);
+    return -1;
+  }
+  /* child process                 */
+  else if  (my_pid == 0) {
+    fms_periodic_run();
+  }
+  /* succesful fork parent process */
+  
+  /* install signal handler */
+  struct sigaction my_sigaction = {.sa_handler = periodic_handler };
+  if (sigaction(SIGUSR1, &my_sigaction, NULL)) {
+    TRACE(TRACE_ERROR,"fms_periodic : unable to install signal handler : %s (%d)\n", strerror(errno), errno);
+    return -1;
+  }
+  
+  /* set main process priority */
+  struct sched_param param;
+  param.sched_priority = 49;
+  if (sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
+    TRACE(TRACE_ERROR,"fms_periodic : hs sched_setscheduler failed : %s (%d)\n", strerror(errno), errno);
+  }
+
+  return 0;
+}
+
+static void fms_periodic_delete(void) {
+
+}
+
+
+#define NS_PER_SEC         1000000000
+#define PERIODIC_DT_NSEC  (NS_PER_SEC/(2*FMS_PERIODIC_FREQ))
+
+static void fms_periodic_run(void) {
+
+  struct sched_param param;
+  param.sched_priority = 95;
+  if (sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
+    TRACE(TRACE_ERROR,"fms_periodic : hs sched_setscheduler failed : %s (%d)\n", strerror(errno), errno);
+  }
+
+  pid_t father_pid = getppid();
+
+  struct timespec periodic_next;
+  clock_gettime(CLOCK_MONOTONIC, &periodic_next);
+
+  while (1) {
+    periodic_next.tv_nsec += PERIODIC_DT_NSEC;
+    while (periodic_next.tv_nsec > NS_PER_SEC) {
+      periodic_next.tv_nsec -= NS_PER_SEC;
+      periodic_next.tv_sec++;
+    }
+    clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &periodic_next, NULL);
+    kill(father_pid, SIGUSR1);
+  }
+  
+  _exit(EXIT_SUCCESS);
+  
+}
diff --git a/sw/airborne/fms/fms_periodic.h b/sw/airborne/fms/fms_periodic.h
new file mode 100644
index 0000000000..64606e89ec
--- /dev/null
+++ b/sw/airborne/fms/fms_periodic.h
@@ -0,0 +1,31 @@
+/*
+ * $Id$
+ *  
+ * Copyright (C) 2010 Antoine Drouin <poinix@gmail.com>
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA. 
+ *
+ */
+
+
+#ifndef FMS_PERIODIC_H
+#define FMS_PERIODIC_H
+
+extern int fms_periodic_init( void(*periodic_handler)(int) );
+
+#endif /* FMS_PERIODIC_H */