1 /** @file 2 Math worker functions. 3 4 Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR> 5 This program and the accompanying materials 6 are licensed and made available under the terms and conditions of the BSD License 7 which accompanies this distribution. The full text of the license may be found at 8 http://opensource.org/licenses/bsd-license.php. 9 10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 12 13 **/ 14 15 16 17 18 #include "BaseLibInternals.h" 19 20 /** 21 Returns the bit position of the lowest bit set in a 64-bit value. 22 23 This function computes the bit position of the lowest bit set in the 64-bit 24 value specified by Operand. If Operand is zero, then -1 is returned. 25 Otherwise, a value between 0 and 63 is returned. 26 27 @param Operand The 64-bit operand to evaluate. 28 29 @retval 0..63 The lowest bit set in Operand was found. 30 @retval -1 Operand is zero. 31 32 33 **/ 34 INTN 35 EFIAPI 36 LowBitSet64 ( 37 IN UINT64 Operand 38 ) 39 { 40 INTN BitIndex; 41 42 if (Operand == 0) { 43 return -1; 44 } 45 46 for (BitIndex = 0; 47 (Operand & 1) == 0; 48 BitIndex++, Operand = RShiftU64 (Operand, 1)); 49 return BitIndex; 50 } 51
