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