1 files changed, 67 insertions, 0 deletions
diff --git a/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm b/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm
new file mode 100644
index 0000000..9f0d962
--- /dev/null
+++ b/EDK/Foundation/Library/EfiCommonLib/Ia32/GetPowerOfTwo.asm
@@ -0,0 +1,67 @@
+      TITLE   GetPowerOfTwo.asm: Calculates the power of two value just below input
+
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2005 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:
+;
+;   GetPowerOfTwo.asm
+; 
+; Abstract:
+; 
+;   Calculates the largest integer that is both 
+;   a power of two and less than Input
+;
+;------------------------------------------------------------------------------
+
+  .686P
+  .XMM
+  .MODEL SMALL
+  .CODE
+  
+_GetPowerOfTwo  PROC
+;------------------------------------------------------------------------------
+; UINT32
+; _GetPowerOfTwo (
+;   IN UINT32   Input
+;   )
+;
+; Routine Description:
+;
+;   Calculates the largest integer that is both 
+;   a power of two and less than Input
+;
+; Arguments:
+;
+;   Input  - value to calculate power of two
+;
+; Returns:
+;
+;   the largest integer that is both  a power of 
+;   two and less than Input
+;------------------------------------------------------------------------------
+    xor     eax, eax
+    mov     edx, eax
+    mov     ecx, [esp + 8]
+    jecxz   @F
+    bsr     ecx, ecx
+    bts     edx, ecx
+    jmp     @Exit
+@@:
+    mov     ecx, [esp + 4]
+    jecxz   @Exit
+    bsr     ecx, ecx
+    bts     eax, ecx
+@Exit:
+    ret
+_GetPowerOfTwo  ENDP
+
+END