1 /*++ 2 3 Copyright (c) 2004 - 2006, Intel Corporation. All rights reserved.<BR> 4 This program and the accompanying materials 5 are licensed and made available under the terms and conditions of the BSD License 6 which accompanies this distribution. The full text of the license may be found at 7 http://opensource.org/licenses/bsd-license.php 8 9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 11 12 13 Module Name: 14 15 HighBitSet32.c 16 17 Abstract: 18 19 Math worker functions. 20 21 --*/ 22 23 #include "BaseLibInternals.h" 24 25 /** 26 Returns the bit position of the highest bit set in a 32-bit value. Equivalent 27 to log2(x). 28 29 This function computes the bit position of the highest bit set in the 32-bit 30 value specified by Operand. If Operand is zero, then -1 is returned. 31 Otherwise, a value between 0 and 31 is returned. 32 33 @param Operand The 32-bit operand to evaluate. 34 35 @return Position of the highest bit set in Operand if found. 36 @retval -1 Operand is zero. 37 38 **/ 39 INTN 40 EFIAPI 41 HighBitSet32 ( 42 IN UINT32 Operand 43 ) 44 { 45 INTN BitIndex; 46 47 if (Operand == 0) { 48 return - 1; 49 } 50 for (BitIndex = 31; (INT32)Operand > 0; BitIndex--, Operand <<= 1); 51 return BitIndex; 52 } 53
