#ifdef GEN_INTELLISENSE_DIRECTIVES
#	pragma once
#	include "filesystem.cpp"
#endif

#pragma region Timing
GEN_API_C_BEGIN

#ifdef GEN_BENCHMARK
	#if defined( GEN_COMPILER_MSVC ) && ! defined( __clang__ )
	u64 read_cpu_time_stamp_counter( void )
	{
		return __rdtsc();
	}
	#elif defined( __i386__ )
	u64 read_cpu_time_stamp_counter( void )
	{
		u64 x;
		__asm__ volatile( ".byte 0x0f, 0x31" : "=A"( x ) );
		return x;
	}
	#elif defined( __x86_64__ )
	u64 read_cpu_time_stamp_counter( void )
	{
		u32 hi, lo;
		__asm__ __volatile__( "rdtsc" : "=a"( lo ), "=d"( hi ) );
		return scast( u64, lo ) | ( scast( u64, hi ) << 32 );
	}
	#elif defined( __powerpc__ )
	u64 read_cpu_time_stamp_counter( void )
	{
		u64 result = 0;
		u32 upper, lower, tmp;
		__asm__ volatile(
			"0:                   \n"
			"\tmftbu   %0         \n"
			"\tmftb    %1         \n"
			"\tmftbu   %2         \n"
			"\tcmpw    %2,%0      \n"
			"\tbne     0b         \n"
			: "=r"( upper ), "=r"( lower ), "=r"( tmp )
		);
		result = upper;
		result = result << 32;
		result = result | lower;

		return result;
	}
	#elif defined( GEN_SYSTEM_EMSCRIPTEN )
	u64 read_cpu_time_stamp_counter( void )
	{
		return ( u64 )( emscripten_get_now() * 1e+6 );
	}
	#elif defined( GEN_CPU_ARM ) && ! defined( GEN_COMPILER_TINYC )
	u64 read_cpu_time_stamp_counter( void )
	{
	#	if defined( __aarch64__ )
		int64_t r = 0;
		asm volatile( "mrs %0, cntvct_el0" : "=r"( r ) );
	#	elif ( __ARM_ARCH >= 6 )
		uint32_t r = 0;
		uint32_t pmccntr;
		uint32_t pmuseren;
		uint32_t pmcntenset;

		// Read the user mode perf monitor counter access permissions.
		asm volatile( "mrc p15, 0, %0, c9, c14, 0" : "=r"( pmuseren ) );
		if ( pmuseren & 1 )
		{    // Allows reading perfmon counters for user mode code.
			asm volatile( "mrc p15, 0, %0, c9, c12, 1" : "=r"( pmcntenset ) );
			if ( pmcntenset & 0x80000000ul )
			{    // Is it counting?
				asm volatile( "mrc p15, 0, %0, c9, c13, 0" : "=r"( pmccntr ) );
				// The counter is set up to count every 64th cycle
				return ( ( int64_t )pmccntr ) * 64;    // Should optimize to << 6
			}
		}
	#	else
	#		error "No suitable method for read_cpu_time_stamp_counter for this cpu type"
	#	endif

		return r;
	}
	#else
	u64 read_cpu_time_stamp_counter( void )
	{
		GEN_PANIC( "read_cpu_time_stamp_counter is not supported on this particular setup" );
		return -0;
	}
	#endif

	#if defined( GEN_SYSTEM_WINDOWS ) || defined( GEN_SYSTEM_CYGWIN )

	u64 time_rel_ms( void )
	{
		local_persist LARGE_INTEGER win32_perf_count_freq = {};
		u64                         result;
		LARGE_INTEGER               counter;
		local_persist LARGE_INTEGER win32_perf_counter = {};
		if ( ! win32_perf_count_freq.QuadPart )
		{
			QueryPerformanceFrequency( &win32_perf_count_freq );
			GEN_ASSERT( win32_perf_count_freq.QuadPart != 0 );
			QueryPerformanceCounter( &win32_perf_counter );
		}

		QueryPerformanceCounter( &counter );

		result = ( counter.QuadPart - win32_perf_counter.QuadPart ) * 1000 / ( win32_perf_count_freq.QuadPart );
		return result;
	}

	#else

	#	if defined( GEN_SYSTEM_LINUX ) || defined( GEN_SYSTEM_FREEBSD ) || defined( GEN_SYSTEM_OPENBSD ) || defined( GEN_SYSTEM_EMSCRIPTEN )
	u64 _unix_gettime( void )
	{
		struct timespec t;
		u64             result;

		clock_gettime( 1 /*CLOCK_MONOTONIC*/, &t );
		result = 1000 * t.tv_sec + 1.0e-6 * t.tv_nsec;
		return result;
	}
	#	endif

	u64 time_rel_ms( void )
	{
	#	if defined( GEN_SYSTEM_OSX )
		u64 result;

		local_persist u64 timebase  = 0;
		local_persist u64 timestart = 0;

		if ( ! timestart )
		{
			mach_timebase_info_data_t tb = { 0 };
			mach_timebase_info( &tb );
			timebase   = tb.numer;
			timebase  /= tb.denom;
			timestart  = mach_absolute_time();
		}

		// NOTE: mach_absolute_time() returns things in nanoseconds
		result = 1.0e-6 * ( mach_absolute_time() - timestart ) * timebase;
		return result;
	#	else
		local_persist u64 unix_timestart = 0.0;

		if ( ! unix_timestart )
		{
			unix_timestart = _unix_gettime();
		}

		u64 now = _unix_gettime();

		return ( now - unix_timestart );
	#	endif
	}
	#endif

	f64 time_rel( void )
	{
		return ( f64 )( time_rel_ms() * 1e-3 );
	}
#endif

GEN_API_C_END
#pragma endregion Timing