Leaked source code of windows server 2003
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/***
*testfdiv.c - routine to test for correct operation of x86 FDIV instruction.
*
* Copyright (c) 1994-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Detects early steppings of Pentium with incorrect FDIV tables using
* 'official' Intel test values. Returns 1 if flawed Pentium is detected,
* 0 otherwise.
*
*Revision History:
* 12-19-94 JWM file added
* 12-22-94 JWM Now safe for TNT, et al
* 01-13-95 JWM underscores added for ANSI compatibility
* 12-12-95 SKS Skip redundant Pentium test on uni-processor systems
* 12-13-95 SKS Call LoadLibrary() rather than GetModuleHandle()
* since "kernel32.dll" is always going to be present.
* 01-18-96 JWM Now handles possible failure of SetThreadAffinityMask(),
* incorporating various suggestions of MarkL.
* 05-29-96 JWM No longer loops through affinity mask; instead, uses MarkL's
* new IsProcessorFeaturePresent() API if possible, only tests
* 1st processor if not.
*
*******************************************************************************/
#include <windows.h>
int _ms_p5_test_fdiv(void)
{
double dTestDivisor = 3145727.0;
double dTestDividend = 4195835.0;
double dRslt;
_asm {
fld qword ptr [dTestDividend]
fdiv qword ptr [dTestDivisor]
fmul qword ptr [dTestDivisor]
fsubr qword ptr [dTestDividend]
fstp qword ptr [dRslt]
}
return (dRslt > 1.0);
}
/*
* Multiprocessor Pentium test: returns 1 if any processor is a flawed
* Pentium, 0 otherwise.
*/
int _ms_p5_mp_test_fdiv(void)
{
#define PF_FLOATING_POINT_PRECISION_ERRATA 0
HINSTANCE LibInst;
FARPROC pIsProcessorFeaturePresent;
if ((LibInst = GetModuleHandle("KERNEL32")) &&
(pIsProcessorFeaturePresent = GetProcAddress(LibInst, "IsProcessorFeaturePresent")))
return (*pIsProcessorFeaturePresent)(PF_FLOATING_POINT_PRECISION_ERRATA);
else
return _ms_p5_test_fdiv();
}