initial commit

LICENSE

+MIT License
+
+Copyright (c) 2011 PJRC.COM, LLC 
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

+elapsedMillis 
+=============
+
+Paul Stoffregen's elapsedMillis and elapsedMicros.
+
+https://www.pjrc.com/teensy/td_timing_elaspedMillis.html

elapsedMillis.h

+/* Elapsed time types - for easy-to-use measurements of elapsed time
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef elapsedMillis_h
+#define elapsedMillis_h
+#ifdef __cplusplus
+
+#if ARDUINO >= 100
+#include "Arduino.h"
+#else
+#include "WProgram.h"
+#endif
+
+class elapsedMillis
+{
+private:
+	unsigned long ms;
+public:
+	elapsedMillis(void) { ms = millis(); }
+	elapsedMillis(unsigned long val) { ms = millis() - val; }
+	elapsedMillis(const elapsedMillis &orig) { ms = orig.ms; }
+	operator unsigned long () const { return millis() - ms; }
+	elapsedMillis & operator = (const elapsedMillis &rhs) { ms = rhs.ms; return *this; }
+	elapsedMillis & operator = (unsigned long val) { ms = millis() - val; return *this; }
+	elapsedMillis & operator -= (unsigned long val)      { ms += val ; return *this; }
+	elapsedMillis & operator += (unsigned long val)      { ms -= val ; return *this; }
+	elapsedMillis operator - (int val) const           { elapsedMillis r(*this); r.ms += val; return r; }
+	elapsedMillis operator - (unsigned int val) const  { elapsedMillis r(*this); r.ms += val; return r; }
+	elapsedMillis operator - (long val) const          { elapsedMillis r(*this); r.ms += val; return r; }
+	elapsedMillis operator - (unsigned long val) const { elapsedMillis r(*this); r.ms += val; return r; }
+	elapsedMillis operator + (int val) const           { elapsedMillis r(*this); r.ms -= val; return r; }
+	elapsedMillis operator + (unsigned int val) const  { elapsedMillis r(*this); r.ms -= val; return r; }
+	elapsedMillis operator + (long val) const          { elapsedMillis r(*this); r.ms -= val; return r; }
+	elapsedMillis operator + (unsigned long val) const { elapsedMillis r(*this); r.ms -= val; return r; }
+};
+
+class elapsedMicros
+{
+private:
+	unsigned long us;
+public:
+	elapsedMicros(void) { us = micros(); }
+	elapsedMicros(unsigned long val) { us = micros() - val; }
+	elapsedMicros(const elapsedMicros &orig) { us = orig.us; }
+	operator unsigned long () const { return micros() - us; }
+	elapsedMicros & operator = (const elapsedMicros &rhs) { us = rhs.us; return *this; }
+	elapsedMicros & operator = (unsigned long val) { us = micros() - val; return *this; }
+	elapsedMicros & operator -= (unsigned long val)      { us += val ; return *this; }
+	elapsedMicros & operator += (unsigned long val)      { us -= val ; return *this; }
+	elapsedMicros operator - (int val) const           { elapsedMicros r(*this); r.us += val; return r; }
+	elapsedMicros operator - (unsigned int val) const  { elapsedMicros r(*this); r.us += val; return r; }
+	elapsedMicros operator - (long val) const          { elapsedMicros r(*this); r.us += val; return r; }
+	elapsedMicros operator - (unsigned long val) const { elapsedMicros r(*this); r.us += val; return r; }
+	elapsedMicros operator + (int val) const           { elapsedMicros r(*this); r.us -= val; return r; }
+	elapsedMicros operator + (unsigned int val) const  { elapsedMicros r(*this); r.us -= val; return r; }
+	elapsedMicros operator + (long val) const          { elapsedMicros r(*this); r.us -= val; return r; }
+	elapsedMicros operator + (unsigned long val) const { elapsedMicros r(*this); r.us -= val; return r; }
+};
+
+#endif // __cplusplus
+#endif // elapsedMillis_h