MdePkg/BaseLib: Preserve EBX register and fix stack offset to LinearAddress in AsmFlu...

[mirror_edk2.git] / MdePkg / Library / BaseLib / Ia32 / CpuId.c

diff --git a/MdePkg/Library/BaseLib/Ia32/CpuId.c b/MdePkg/Library/BaseLib/Ia32/CpuId.c
index 73f12bcaeeb1938a79cd2a2cdd0727e0cdc0753b..09487f77f273899bd3d0b0ff5fd72353c5df9b4e 100644 (file)
--- a/MdePkg/Library/BaseLib/Ia32/CpuId.c
+++ b/MdePkg/Library/BaseLib/Ia32/CpuId.c
@@ -1,22 +1,42 @@
 /** @file\r
   AsmCpuid function.\r
 \r
-  Copyright (c) 2006 - 2007, Intel Corporation<BR>\r
-  All rights reserved. This program and the accompanying materials\r
+  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>\r
+  This program and the accompanying materials\r
   are licensed and made available under the terms and conditions of the BSD License\r
   which accompanies this distribution.  The full text of the license may be found at\r
-  http://opensource.org/licenses/bsd-license.php\r
+  http://opensource.org/licenses/bsd-license.php.\r
 \r
   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
 \r
 **/\r
 \r
-//\r
-// Include common header file for this module.\r
-//\r
+/**\r
+  Retrieves CPUID information.\r
 \r
+  Executes the CPUID instruction with EAX set to the value specified by Index.\r
+  This function always returns Index.\r
+  If Eax is not NULL, then the value of EAX after CPUID is returned in Eax.\r
+  If Ebx is not NULL, then the value of EBX after CPUID is returned in Ebx.\r
+  If Ecx is not NULL, then the value of ECX after CPUID is returned in Ecx.\r
+  If Edx is not NULL, then the value of EDX after CPUID is returned in Edx.\r
+  This function is only available on IA-32 and x64.\r
 \r
+  @param  Index         The 32-bit value to load into EAX prior to invoking the CPUID\r
+                        instruction.\r
+  @param  RegisterEax   A pointer to the 32-bit EAX value returned by the CPUID\r
+                        instruction. This is an optional parameter that may be NULL.\r
+  @param  RegisterEbx   A pointer to the 32-bit EBX value returned by the CPUID\r
+                        instruction. This is an optional parameter that may be NULL.\r
+  @param  RegisterEcx   A pointer to the 32-bit ECX value returned by the CPUID\r
+                        instruction. This is an optional parameter that may be NULL.\r
+  @param  RegisterEdx   A pointer to the 32-bit EDX value returned by the CPUID\r
+                        instruction. This is an optional parameter that may be NULL.\r
+\r
+  @return Index.\r
+\r
+**/\r
 UINT32\r
 EFIAPI\r
 AsmCpuid (\r