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/* $Id$ */

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/** @file os_timer.cpp */

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#include "stdafx.h"

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#undef RDTSC_AVAILABLE

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

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

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

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# if _MSC_VER >= 1400

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#include <intrin.h>

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uint64 _rdtsc()

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{

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	return __rdtsc();

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}

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#	else

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uint64 _declspec(naked) _rdtsc()

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{

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	_asm {

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		rdtsc

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		ret

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	}

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}

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# endif

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# define RDTSC_AVAILABLE

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#endif

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

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

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unsigned __int64 _rdtsc();

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

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# define RDTSC_AVAILABLE

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#endif

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

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

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uint64 _rdtsc()

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{

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	uint32 high, low;

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

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

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}

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# define RDTSC_AVAILABLE

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#endif

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/* rdtsc for PPC which has this not */

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

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uint64 _rdtsc()

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{

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	uint32 high = 0, high2 = 0, low;

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

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

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

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

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	asm volatile (

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				  "mftbu %0\n"

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				  "mftb %1\n"

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				  "mftbu %2\n"

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				  "cmpw %3,%4\n"

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				  "bne- $-16\n"

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

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

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				  );

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

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}

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# define RDTSC_AVAILABLE

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#endif

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

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

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#if !defined(RDTSC_AVAILABLE)

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/* MSVC (in case of WinCE) can't handle #warning */

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# if !defined(_MSC_VER)

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#warning "(non-fatal) No support for rdtsc(), you won't be able to profile with TIC/TOC"

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# endif

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uint64 _rdtsc() {return 0;}

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#endif