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
AsmCpuid(IN UINT32 Index,OUT UINT32 * RegisterEax,OPTIONAL OUT UINT32 * RegisterEbx,OPTIONAL OUT UINT32 * RegisterEcx,OPTIONAL OUT UINT32 * RegisterEdx OPTIONAL)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