1 files changed, 71 insertions, 0 deletions
diff --git a/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.c b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.c
new file mode 100644
index 0000000000..bc909eb78d
--- /dev/null
+++ b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.c
@@ -0,0 +1,71 @@
+/*++
+
+Copyright (c) 2006, Intel Corporation                                                         
+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.             
+
+Module Name:
+
+  RShiftU64.c
+
+Abstract:
+
+  64-bit right shift function for IA-32
+
+--*/
+
+#include "Tiano.h"
+
+UINT64
+RShiftU64 (
+  IN UINT64   Operand,
+  IN UINTN    Count
+  )
+/*++
+
+Routine Description:
+  This routine allows a 64 bit value to be right shifted by 32 bits and returns the 
+  shifted value.
+  Count is valid up 63. (Only Bits 0-5 is valid for Count)
+Arguments:
+  Operand - Value to be shifted
+  Count   - Number of times to shift right.
+ 
+Returns:
+
+  Value shifted right identified by the Count.
+
+--*/
+{
+  __asm {
+  
+    mov    eax, dword ptr Operand[0]
+    mov    edx, dword ptr Operand[4]
+  
+    ;
+    ; CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EDX is not touched
+    ; For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later. 
+    ;
+    mov    ecx, Count
+    and    ecx, 63
+    shrd   eax, edx, cl
+    shr    edx, cl
+
+    cmp    ecx, 32
+    jc     short _RShiftU64_Done
+
+    ;
+    ; Since Count is 32 - 63, edx will have been shifted  by 0 - 31                                                     
+    ; If shifted by 32 or more, set upper 32 bits to zero.
+    ;
+    mov    eax, edx
+    xor    edx, edx
+
+_RShiftU64_Done:
+  }
+}