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git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@10405 6f19259b-4bc3-4df7-8a09-765794883524
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/** @file
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Math worker functions.
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Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include "BaseLibInternals.h"
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/**
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Returns the bit position of the highest bit set in a 64-bit value. Equivalent
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to log2(x).
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This function computes the bit position of the highest bit set in the 64-bit
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value specified by Operand. If Operand is zero, then -1 is returned.
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Otherwise, a value between 0 and 63 is returned.
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@param Operand The 64-bit operand to evaluate.
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@retval 0..63 Position of the highest bit set in Operand if found.
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@retval -1 Operand is zero.
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**/
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INTN
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EFIAPI
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HighBitSet64 (
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IN UINT64 Operand
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)
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{
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if (Operand == (UINT32)Operand) {
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//
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// Operand is just a 32-bit integer
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//
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return HighBitSet32 ((UINT32)Operand);
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}
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//
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// Operand is really a 64-bit integer
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//
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if (sizeof (UINTN) == sizeof (UINT32)) {
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return HighBitSet32 (((UINT32*)&Operand)[1]) + 32;
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} else {
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return HighBitSet32 ((UINT32)RShiftU64 (Operand, 32)) + 32;
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}
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}
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