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author | bbahnsen <bbahnsen@6f19259b-4bc3-4df7-8a09-765794883524> | 2006-04-21 22:54:32 +0000 |
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committer | bbahnsen <bbahnsen@6f19259b-4bc3-4df7-8a09-765794883524> | 2006-04-21 22:54:32 +0000 |
commit | 878ddf1fc3540a715f63594ed22b6929e881afb4 (patch) | |
tree | c56c44dac138137b510e1fba7c3efe5e4d84bea2 /MdePkg/Library/BaseLib/HighBitSet64.c | |
download | edk2-platforms-878ddf1fc3540a715f63594ed22b6929e881afb4.tar.xz |
Initial import.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@3 6f19259b-4bc3-4df7-8a09-765794883524
Diffstat (limited to 'MdePkg/Library/BaseLib/HighBitSet64.c')
-rw-r--r-- | MdePkg/Library/BaseLib/HighBitSet64.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseLib/HighBitSet64.c b/MdePkg/Library/BaseLib/HighBitSet64.c new file mode 100644 index 0000000000..50889777b5 --- /dev/null +++ b/MdePkg/Library/BaseLib/HighBitSet64.c @@ -0,0 +1,43 @@ +/** @file
+ Math worker functions.
+
+ Copyright (c) 2006, Intel Corporation<BR>
+ 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.
+
+**/
+
+#include "BaseLibInternals.h"
+
+/**
+ Returns the bit position of the highest bit set in a 64-bit value. Equivalent
+ to log2(x).
+
+ This function computes the bit position of the highest bit set in the 64-bit
+ value specified by Operand. If Operand is zero, then -1 is returned.
+ Otherwise, a value between 0 and 63 is returned.
+
+ @param Operand The 64-bit operand to evaluate.
+
+ @return Position of the highest bit set in Operand if found.
+ @retval -1 Operand is zero.
+
+**/
+INTN
+EFIAPI
+HighBitSet64 (
+ IN UINT64 Operand
+ )
+{
+ INTN BitIndex;
+
+ for (BitIndex = -1;
+ Operand != 0;
+ BitIndex++, Operand = RShiftU64 (Operand, 1));
+ return BitIndex;
+}
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