Added period checking in RandomInput to reduce CPU load

linux/libio/RandomInput.cpp

@@ -23,13 +23,16 @@
  * ============================================================ */
 
 #include "RandomInput.h"
+#include "TimeUtils.h"
 #include <stdlib.h>
 #include <stdexcept>
+#include <unistd.h>
 
 namespace tactile {
 
-RandomInput::RandomInput(size_t noTaxels)
-   : InputInterface(noTaxels)
+RandomInput::RandomInput(size_t noTaxels, const uint64_t period)
+   : InputInterface(noTaxels),
+  period(period)
 {
 	// initialize smallest values
 	data[1] = 2048;
@@ -39,6 +42,7 @@ RandomInput::RandomInput(size_t noTaxels)
 void RandomInput::connect(const std::string &dummy)
 {
 	connected = true;
+	prev_time = getMicroseconds();
 }
 
 void RandomInput::disconnect()
@@ -49,7 +53,8 @@ void RandomInput::disconnect()
 const InputInterface::data_vector& RandomInput::readFrame()
 {
 	if (!connected) throw std::runtime_error("not connected");
-
+
+	// first prepare data (takes some time)
 	size_t idx = 0;
 	for (data_vector::iterator it=data.begin(), end=data.end(); it != end; ++it, ++idx) {
 		long int rndnumber = random();
@@ -60,6 +65,18 @@ const InputInterface::data_vector& RandomInput::readFrame()
 			if (idx == 14) *it = std::min<data_type>(*it + 3700, 0xFFF); // goniometer joint value
 		}
 	}
+	// then check time elapsed
+	uint64_t cur_time = getMicroseconds();
+	uint64_t time_diff_us = cur_time - prev_time;
+	//printf("time us %ld\n", time_diff_us);
+
+	// if required wait until period has passed
+	if (time_diff_us < period)
+	{
+		usleep(period - time_diff_us);
+	}
+
+	prev_time = getMicroseconds();  // store time when returning the data
 	return data;
 }
 

linux/libio/RandomInput.h

@@ -30,10 +30,18 @@ namespace tactile {
 class RandomInput : public InputInterface
 {
 public:
-	RandomInput(size_t noTaxels);
+	RandomInput(size_t noTaxels, const uint64_t period=1000);
 	void connect(const std::string &dummy);
 	void disconnect();
 	const data_vector& readFrame ();
+	void setPeriod(const uint64_t microseconds)  // set period in microseconds
+	{
+		period = microseconds;
+	};
+
+private:
+	uint64_t period;  // period in microseconds
+	uint64_t prev_time;
 };
 
 }

linux/libio/TimeUtils.cpp

@@ -0,0 +1,46 @@
+/* ============================================================
+ *
+ * Copyright (C) 2022 by Guillaume Walck <gwalck at techfak dot uni-bielefeld dot de>
+ *
+ * This file may be licensed under the terms of the
+ * GNU Lesser General Public License Version 3 (the "LGPL"),
+ * or (at your option) any later version.
+ *
+ * Software distributed under the License is distributed
+ * on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
+ * express or implied. See the LGPL for the specific language
+ * governing rights and limitations.
+ *
+ * You should have received a copy of the LGPL along with this
+ * program. If not, go to http://www.gnu.org/licenses/lgpl.html
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The development of this software was supported by:
+ *   CITEC, "Cognitive Interaction Technology" Excellence Cluster
+ *     Bielefeld University
+ *
+ * ============================================================ */
+#include "TimeUtils.h"
+
+/// Convert seconds to microseconds
+#define SEC_TO_US(sec) ((sec) * 1000000) 
+
+uint64_t getMicroseconds()
+{
+	uint64_t microseconds;
+	struct timespec ts;
+	int return_code = timespec_get(&ts, TIME_UTC);
+	if (return_code == 0)
+	{
+		printf("Failed to obtain timestamp.\n");
+		microseconds = UINT64_MAX; // use this to indicate error
+	}
+	else
+	{
+		// `ts` now contains your timestamp in seconds and nanoseconds! To 
+		// convert the whole struct to nanoseconds, do this:
+		microseconds = SEC_TO_US((uint64_t)ts.tv_sec) + ((uint64_t)ts.tv_nsec) / 1000;
+	}
+	return microseconds;
+}

linux/libio/TimeUtils.h

@@ -0,0 +1,31 @@
+/* ============================================================
+ *
+ * Copyright (C) 2022 by Guillaume Walck <gwalck at techfak dot uni-bielefeld dot de>
+ *
+ * This file may be licensed under the terms of the
+ * GNU Lesser General Public License Version 3 (the "LGPL"),
+ * or (at your option) any later version.
+ *
+ * Software distributed under the License is distributed
+ * on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
+ * express or implied. See the LGPL for the specific language
+ * governing rights and limitations.
+ *
+ * You should have received a copy of the LGPL along with this
+ * program. If not, go to http://www.gnu.org/licenses/lgpl.html
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The development of this software was supported by:
+ *   CITEC, "Cognitive Interaction Technology" Excellence Cluster
+ *     Bielefeld University
+ *
+ * ============================================================ */
+#pragma once
+
+#include <stdint.h>  // `UINT64_MAX`
+#include <unistd.h>
+#include <stdio.h>  // `printf()`
+#include <time.h>   // `timespec_get()`
+
+uint64_t getMicroseconds();