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/** @file
AsmCpuid function.
Copyright (c) 2006 - 2007, Intel Corporation<BR>
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
//
// Include common header file for this module.
//
/**
Retrieves CPUID information.
Executes the CPUID instruction with EAX set to the value specified by Index.
This function always returns Index.
If Eax is not NULL, then the value of EAX after CPUID is returned in Eax.
If Ebx is not NULL, then the value of EBX after CPUID is returned in Ebx.
If Ecx is not NULL, then the value of ECX after CPUID is returned in Ecx.
If Edx is not NULL, then the value of EDX after CPUID is returned in Edx.
This function is only available on IA-32 and X64.
@param Index The 32-bit value to load into EAX prior to invoking the CPUID
instruction.
@param Eax Pointer to the 32-bit EAX value returned by the CPUID
instruction. This is an optional parameter that may be NULL.
@param Ebx Pointer to the 32-bit EBX value returned by the CPUID
instruction. This is an optional parameter that may be NULL.
@param Ecx Pointer to the 32-bit ECX value returned by the CPUID
instruction. This is an optional parameter that may be NULL.
@param Edx Pointer to the 32-bit EDX value returned by the CPUID
instruction. This is an optional parameter that may be NULL.
@return Index
**/
UINT32
EFIAPI
AsmCpuid (
IN UINT32 Index,
OUT UINT32 *RegisterEax, OPTIONAL
OUT UINT32 *RegisterEbx, OPTIONAL
OUT UINT32 *RegisterEcx, OPTIONAL
OUT UINT32 *RegisterEdx OPTIONAL
)
{
_asm {
mov eax, Index
cpuid
push ecx
mov ecx, RegisterEax
jecxz SkipEax
mov [ecx], eax
SkipEax:
mov ecx, RegisterEbx
jecxz SkipEbx
mov [ecx], ebx
SkipEbx:
pop eax
mov ecx, RegisterEcx
jecxz SkipEcx
mov [ecx], eax
SkipEcx:
mov ecx, RegisterEdx
jecxz SkipEdx
mov [ecx], edx
SkipEdx:
mov eax, Index
}
}
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