text: /*
    Copyright (c) 2011 Arduino.  All right reserved.
  
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
  
    This library 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 Lesser General Public License for more details.
  
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    
    Modified 7 Feb 2017 by Ajay Bhargav <ajay.bhargav@waybyte.in>
  */
  
  #include "Arduino.h"
  #include "wiring_private.h"
  
  static unsigned long pulseInCommon(uint8_t pin, uint8_t state, unsigned long timeout)
  {
  	int ioHandle = g_ioHandles[pin];
  	int stateMask = state ? GPIO_LEVEL_HIGH : GPIO_LEVEL_LOW;
  
  	unsigned long startMicros = micros();
  
  	// wait for any previous pulse to end
  	while (gpio_read(ioHandle) == stateMask) {
  		if (micros() - startMicros > timeout)
  			return 0;
  	}
  
  	// wait for the pulse to start
  	while (gpio_read(ioHandle) != stateMask) {
  		if (micros() - startMicros > timeout)
  			return 0;
  	}
  
  	unsigned long start = micros();
  
  	// wait for the pulse to stop
  	while (gpio_read(ioHandle) == stateMask) {
  		if (micros() - startMicros > timeout)
  			return 0;
  	}
  	return micros() - start;
  }
  
  /* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
   * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
   * to 3 minutes in length, but must be called at least a few dozen microseconds
   * before the start of the pulse.
   *
   * ATTENTION:
   * This function performs better with short pulses in noInterrupt() context
   */
  uint32_t pulseIn( uint32_t pin, uint32_t state, uint32_t timeout )
  {
  	return pulseInCommon(pin, state, timeout);
  }
  
  /* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
   * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
   * to 3 minutes in length, but must be called at least a few dozen microseconds
   * before the start of the pulse.
   *
   * ATTENTION:
   * this function relies on micros() so cannot be used in noInterrupt() context
   */
  uint32_t pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout)
  {
  	return pulseInCommon(pin, state, timeout);
  }
  