1 /** @file 2 AsmCpuid function. 3 4 Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR> 5 This program and the accompanying materials 6 are licensed and made available under the terms and conditions of the BSD License 7 which accompanies this distribution. The full text of the license may be found at 8 http://opensource.org/licenses/bsd-license.php. 9 10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 12 13 **/ 14 15 /** 16 Retrieves CPUID information. 17 18 Executes the CPUID instruction with EAX set to the value specified by Index. 19 This function always returns Index. 20 If Eax is not NULL, then the value of EAX after CPUID is returned in Eax. 21 If Ebx is not NULL, then the value of EBX after CPUID is returned in Ebx. 22 If Ecx is not NULL, then the value of ECX after CPUID is returned in Ecx. 23 If Edx is not NULL, then the value of EDX after CPUID is returned in Edx. 24 This function is only available on IA-32 and x64. 25 26 @param Index The 32-bit value to load into EAX prior to invoking the CPUID 27 instruction. 28 @param RegisterEax A pointer to the 32-bit EAX value returned by the CPUID 29 instruction. This is an optional parameter that may be NULL. 30 @param RegisterEbx A pointer to the 32-bit EBX value returned by the CPUID 31 instruction. This is an optional parameter that may be NULL. 32 @param RegisterEcx A pointer to the 32-bit ECX value returned by the CPUID 33 instruction. This is an optional parameter that may be NULL. 34 @param RegisterEdx A pointer to the 32-bit EDX value returned by the CPUID 35 instruction. This is an optional parameter that may be NULL. 36 37 @return Index. 38 39 **/ 40 UINT32 41 EFIAPI 42 AsmCpuid ( 43 IN UINT32 Index, 44 OUT UINT32 *RegisterEax, OPTIONAL 45 OUT UINT32 *RegisterEbx, OPTIONAL 46 OUT UINT32 *RegisterEcx, OPTIONAL 47 OUT UINT32 *RegisterEdx OPTIONAL 48 ) 49 { 50 _asm { 51 mov eax, Index 52 cpuid 53 push ecx 54 mov ecx, RegisterEax 55 jecxz SkipEax 56 mov [ecx], eax 57 SkipEax: 58 mov ecx, RegisterEbx 59 jecxz SkipEbx 60 mov [ecx], ebx 61 SkipEbx: 62 pop eax 63 mov ecx, RegisterEcx 64 jecxz SkipEcx 65 mov [ecx], eax 66 SkipEcx: 67 mov ecx, RegisterEdx 68 jecxz SkipEdx 69 mov [ecx], edx 70 SkipEdx: 71 mov eax, Index 72 } 73 } 74 75
