Fix the bug that if code is run above 4G, AsmDisablePaging64 will be failure.

[mirror_edk2.git] / MdePkg / Library / BaseLib / GetPowerOfTwo64.c

diff --git a/MdePkg/Library/BaseLib/GetPowerOfTwo64.c b/MdePkg/Library/BaseLib/GetPowerOfTwo64.c
index 9994fb8f12e29acd8cc6cf2bfbebc13deb1d5735..ae85b91180282886277326f0dd341771c52de2e6 100644 (file)
--- a/MdePkg/Library/BaseLib/GetPowerOfTwo64.c
+++ b/MdePkg/Library/BaseLib/GetPowerOfTwo64.c
@@ -1,7 +1,7 @@
 /** @file\r
   Math worker functions.\r
 \r
-  Copyright (c) 2006, Intel Corporation<BR>\r
+  Copyright (c) 2006 - 2008, Intel Corporation<BR>\r
   All rights reserved. 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
@@ -12,11 +12,14 @@
 \r
 **/\r
 \r
+\r
+\r
+\r
 #include "BaseLibInternals.h"\r
 \r
 /**\r
   Returns the value of the highest bit set in a 64-bit value. Equivalent to\r
-  1 << HighBitSet64(x).\r
+  1 << log2(x).\r
 \r
   This function computes the value of the highest bit set in the 64-bit value\r
   specified by Operand. If Operand is zero, then zero is returned.\r
@@ -33,7 +36,9 @@ GetPowerOfTwo64 (
   IN      UINT64                    Operand\r
   )\r
 {\r
-  INTN                              BitPos;\r
+  if (Operand == 0) {\r
+    return 0;\r
+  }\r
 \r
-  return (BitPos = HighBitSet64 (Operand)) > 0 ? LShiftU64 (1, BitPos) : 0;\r
+  return LShiftU64 (1, HighBitSet64 (Operand));\r
 }\r