| #/*++ | |
| # | |
| #Copyright (c) 2006, 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. | |
| # | |
| #Module Name: | |
| # | |
| # GetPowerOfTwo.c | |
| # | |
| #Abstract: | |
| # | |
| # Calculates the largest integer that is both | |
| # a power of two and less than Input | |
| # | |
| #--*/ | |
| #include "EfiBind.h" | |
| #--------------------------------------------------------------------------- | |
| .686: | |
| #.MODEL flat,C | |
| .code: | |
| #--------------------------------------------------------------------------- | |
| .globl ASM_PFX(GetPowerOfTwo) | |
| #UINT64 | |
| #GetPowerOfTwo ( | |
| # IN UINT64 Input | |
| # ) | |
| #/*++ | |
| # | |
| #Routine Description: | |
| # | |
| # Calculates the largest integer that is both | |
| # a power of two and less than Input | |
| # | |
| #Arguments: | |
| # | |
| # Input - value to calculate power of two | |
| # | |
| #Returns: | |
| # | |
| # the largest integer that is both a power of | |
| # two and less than Input | |
| # | |
| #--*/ | |
| ASM_PFX(GetPowerOfTwo): | |
| xorl %eax, %eax | |
| movl %eax, %edx | |
| movl 8(%esp), %ecx # dword ptr Input[4] | |
| jecxz _F | |
| bsrl %ecx, %ecx | |
| btsl %ecx, %edx | |
| jmp _Exit | |
| _F: | |
| movl 4(%esp), %ecx # dword ptr Input[0] | |
| jecxz _Exit | |
| bsrl %ecx, %ecx | |
| btsl %ecx, %eax | |
| _Exit: | |
| ret | |
| #GetPowerOfTwo ENDP | |