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 8372a7f1361594ff413134c574edb82d4c83d26e..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
@@ -33,8 +36,9 @@ GetPowerOfTwo64 (
   IN      UINT64                    Operand\r
   )\r
 {\r
-  INTN                              BitPos;\r
+  if (Operand == 0) {\r
+    return 0;\r
+  }\r
 \r
-  BitPos = HighBitSet64 (Operand);\r
-  return BitPos >= 0 ? LShiftU64 (1, BitPos) : 0;\r
+  return LShiftU64 (1, HighBitSet64 (Operand));\r
 }\r