Import some basic libraries instances for Mde Packages.

[mirror_edk2.git] / MdePkg / Library / BaseLib / HighBitSet32.c

diff --git a/MdePkg/Library/BaseLib/HighBitSet32.c b/MdePkg/Library/BaseLib/HighBitSet32.c
new file mode 100644 (file)
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+++ b/MdePkg/Library/BaseLib/HighBitSet32.c
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+/** @file\r
+  Math worker functions.\r
+\r
+  Copyright (c) 2006, 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
+  http://opensource.org/licenses/bsd-license.php\r
+\r
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+\r
+**/\r
+\r
+//\r
+// Include common header file for this module.\r
+//\r
+#include "CommonHeader.h"\r
+\r
+#include "BaseLibInternals.h"\r
+\r
+/**\r
+  Returns the bit position of the highest bit set in a 32-bit value. Equivalent\r
+  to log2(x).\r
+\r
+  This function computes the bit position of the highest bit set in the 32-bit\r
+  value specified by Operand. If Operand is zero, then -1 is returned.\r
+  Otherwise, a value between 0 and 31 is returned.\r
+\r
+  @param  Operand The 32-bit operand to evaluate.\r
+\r
+  @return Position of the highest bit set in Operand if found.\r
+  @retval -1  Operand is zero.\r
+\r
+**/\r
+INTN\r
+EFIAPI\r
+HighBitSet32 (\r
+  IN      UINT32                    Operand\r
+  )\r
+{\r
+  INTN                              BitIndex;\r
+\r
+  if (Operand == 0) {\r
+    return - 1;\r
+  }\r
+  for (BitIndex = 31; (INT32)Operand > 0; BitIndex--, Operand <<= 1);\r
+  return BitIndex;\r
+}\r