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 highest bit set in a 64-bit value. Equivalent 22 to log2(x). 23 24 This function computes the bit position of the highest bit set in the 64-bit 25 value specified by Operand. If Operand is zero, then -1 is returned. 26 Otherwise, a value between 0 and 63 is returned. 27 28 @param Operand The 64-bit operand to evaluate. 29 30 @retval 0..63 Position of the highest bit set in Operand if found. 31 @retval -1 Operand is zero. 32 33 **/ 34 INTN 35 EFIAPI 36 HighBitSet64 ( 37 IN UINT64 Operand 38 ) 39 { 40 if (Operand == (UINT32)Operand) { 41 // 42 // Operand is just a 32-bit integer 43 // 44 return HighBitSet32 ((UINT32)Operand); 45 } 46 47 // 48 // Operand is really a 64-bit integer 49 // 50 if (sizeof (UINTN) == sizeof (UINT32)) { 51 return HighBitSet32 (((UINT32*)&Operand)[1]) + 32; 52 } else { 53 return HighBitSet32 ((UINT32)RShiftU64 (Operand, 32)) + 32; 54 } 55 } 56
