// Copyright 2018 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

#include <pthread.h>
#include <cassert>
#include <emscripten.h>
#include <emscripten/threading.h>
#include <math.h>
#include <stdio.h>

volatile int threadStarted = 0;
volatile int timeReceived = 0;
volatile double mainThreadTime;

void wait(volatile int *address)
{
	int state = emscripten_atomic_load_u32((void*)address);
	while(state == 0)
		state = emscripten_atomic_load_u32((void*)address);
}

void wake(volatile int *address)
{
	emscripten_atomic_store_u32((void*)address, 1);
}

void *thread_main(void *arg)
{
	wake(&threadStarted);
	wait(&timeReceived);
	double pthreadTime = emscripten_get_now();
	double timeDifference = pthreadTime - mainThreadTime;
	printf("Time difference between pthread and main thread is %f msecs.\n", timeDifference);

	// The time difference here should be well less than 1 msec, but test against 200msecs to be super-sure.
	assert(fabs(timeDifference) < 200);
	emscripten_force_exit(0);
	return 0;
}

void busy_sleep(double msecs)
{
	double end = emscripten_get_now() + msecs;
	while(emscripten_get_now() < end)
		;
}

int main()
{
	// Cause a one second delay between main() and pthread start that might have a chance to drift the wallclocks on emscripten_get_now().
	busy_sleep(1000);

	pthread_t thread;
	pthread_create(&thread, NULL, thread_main, NULL);
	wait(&threadStarted);
	mainThreadTime = emscripten_get_now();
	wake(&timeReceived);

	emscripten_exit_with_live_runtime();
}