/* $Id$ */

#include "stdafx.h"

#undef RDTSC_AVAILABLE

/* rdtsc for MSC_VER, uses simple inline assembly, or _rdtsc

 * from external win64.asm because VS2005 does not support inline assembly */

#if defined(_MSC_VER) && !defined(RDTSC_AVAILABLE)

# if defined (_M_AMD64)

extern uint64 _rdtsc(void);

#	else

uint64 _declspec(naked) _rdtsc(void)

{

	_asm {

		rdtsc

		ret

	}

}

# endif

# define RDTSC_AVAILABLE

#endif

/* rdtsc for OS/2. Hopefully this works, who knows */

#if defined (__WATCOMC__) && !defined(RDTSC_AVAILABLE)

unsigned __int64 _rdtsc( void);

# pragma aux _rdtsc = 0x0F 0x31 value [edx eax] parm nomemory modify exact [edx eax] nomemory;

# define RDTSC_AVAILABLE

#endif

/* rdtsc for all other *nix-en (hopefully). Use GCC syntax */

#if defined(__i386__) || defined(__x86_64__) && !defined(RDTSC_AVAILABLE)

uint64 _rdtsc(void)

{

	uint32 high, low;

	__asm__ __volatile__ ("rdtsc" : "=a" (low), "=d" (high));

	return ((uint64)high << 32) | low;

}

# define RDTSC_AVAILABLE

#endif

/* rdtsc for PPC which has this not */

#if defined(__POWERPC__) && !defined(RDTSC_AVAILABLE)

uint64 _rdtsc(void)

{

	uint32 high = 0, high2 = 0, low;

	/* PPC does not have rdtsc, so we cheat by reading the two 32-bit time-counters

	 * it has, 'Move From Time Base (Upper)'. Since these are two reads, in the

	 * very unlikely event that the lower part overflows to the upper part while we

	 * read it; we double-check and reread the registers */

	asm volatile (

				  "mftbu %0\n"

				  "mftb %1\n"

				  "mftbu %2\n"

				  "cmpw %3,%4\n"

				  "bne- $-16\n"

				  : "=r" (high), "=r" (low), "=r" (high2)

				  : "0" (high), "2" (high2)

				  );

	return ((uint64)high << 32) | low;

}

# define RDTSC_AVAILABLE

#endif

/* In all other cases we have no support for rdtsc. No major issue,

 * you just won't be able to profile your code with TIC()/TOC() */

#if !defined(RDTSC_AVAILABLE)

#warning "OS has no support for rdtsc()"

uint64 _rdtsc(void) {return 0;}

#endif