[SOLVED] pulsein (unimplemented)

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(led, OUTPUT);
  pinMode(led2, OUTPUT);
  Serial.begin (115200);

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
*/

#include "Arduino.h"
#include "wiring_private.h"

/* 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. */
extern uint32_t pulseIn( uint32_t pin, uint32_t state, uint32_t timeout )
{
// cache the port and bit of the pin in order to speed up the
// pulse width measuring loop and achieve finer resolution. calling
// digitalRead() instead yields much coarser resolution.
PinDescription p = g_APinDescription[pin];
uint32_t width = 0; // keep initialization out of time critical area

// convert the timeout from microseconds to a number of times through
// the initial loop; it takes 22 clock cycles per iteration.
uint32_t numloops = 0;
uint32_t maxloops = microsecondsToClockCycles(timeout) / 22;

// wait for any previous pulse to end
while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) == state)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to start
while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) != state)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to stop
while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) == state) {
if (numloops++ == maxloops)
return 0;
width++;
}

// convert the reading to microseconds. The loop has been determined
// to be 52 clock cycles long and have about 16 clocks between the edge
// and the start of the loop. There will be some error introduced by
// the interrupt handlers.
return clockCyclesToMicroseconds(width * 52 + 16);
}

/* 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. */
uint32_t pulseIn( uint32_t pin, uint32_t state, uint32_t timeout )
{
// cache the port and bit of the pin in order to speed up the
// pulse width measuring loop and achieve finer resolution. calling
// digitalRead() instead yields much coarser resolution.

gpio_dev *dev=PIN_MAP[pin].gpio_device;
uint32_t bit = (1U << PIN_MAP[pin].gpio_bit);

uint32_t width = 0; // keep initialization out of time critical area

// convert the timeout from microseconds to a number of times through
// the initial loop; it takes 22 clock cycles per iteration.
uint32_t numloops = 0;
uint32_t maxloops = microsecondsToClockCycles(timeout) / 22;

// wait for any previous pulse to end
while ( (dev->regs->IDR & bit) == state)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to start
while ((dev->regs->IDR & bit) != state)
if (numloops++ == maxloops)
return 0;

// wait for the pulse to stop
while ((dev->regs->IDR & bit) == state) {
if (numloops++ == maxloops)
return 0;
width++;
}

// convert the reading to microseconds. The loop has been determined
// to be 52 clock cycles long and have about 16 clocks between the edge
// and the start of the loop. There will be some error introduced by
// the interrupt handlers.
return clockCyclesToMicroseconds(width * 52 + 16);
}