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69 lines
2.2 KiB
C
69 lines
2.2 KiB
C
/** @file
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AsmCpuid function.
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Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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/**
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Retrieves CPUID information.
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Executes the CPUID instruction with EAX set to the value specified by Index.
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This function always returns Index.
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If Eax is not NULL, then the value of EAX after CPUID is returned in Eax.
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If Ebx is not NULL, then the value of EBX after CPUID is returned in Ebx.
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If Ecx is not NULL, then the value of ECX after CPUID is returned in Ecx.
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If Edx is not NULL, then the value of EDX after CPUID is returned in Edx.
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This function is only available on IA-32 and x64.
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@param Index The 32-bit value to load into EAX prior to invoking the CPUID
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instruction.
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@param RegisterEax A pointer to the 32-bit EAX value returned by the CPUID
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instruction. This is an optional parameter that may be NULL.
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@param RegisterEbx A pointer to the 32-bit EBX value returned by the CPUID
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instruction. This is an optional parameter that may be NULL.
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@param RegisterEcx A pointer to the 32-bit ECX value returned by the CPUID
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instruction. This is an optional parameter that may be NULL.
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@param RegisterEdx A pointer to the 32-bit EDX value returned by the CPUID
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instruction. This is an optional parameter that may be NULL.
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@return Index.
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**/
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UINT32
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EFIAPI
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AsmCpuid (
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IN UINT32 Index,
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OUT UINT32 *RegisterEax, OPTIONAL
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OUT UINT32 *RegisterEbx, OPTIONAL
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OUT UINT32 *RegisterEcx, OPTIONAL
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OUT UINT32 *RegisterEdx OPTIONAL
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)
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{
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_asm {
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mov eax, Index
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cpuid
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push ecx
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mov ecx, RegisterEax
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jecxz SkipEax
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mov [ecx], eax
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SkipEax:
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mov ecx, RegisterEbx
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jecxz SkipEbx
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mov [ecx], ebx
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SkipEbx:
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pop eax
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mov ecx, RegisterEcx
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jecxz SkipEcx
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mov [ecx], eax
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SkipEcx:
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mov ecx, RegisterEdx
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jecxz SkipEdx
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mov [ecx], edx
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SkipEdx:
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mov eax, Index
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}
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}
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