| #/*++ | |
| # | |
| #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: | |
| # | |
| # RShiftU64.c | |
| # | |
| #Abstract: | |
| # | |
| # 64-bit right shift function for IA-32 | |
| # | |
| #--*/ | |
| # | |
| ##include "Tiano.h" | |
| # | |
| #include "EfiBind.h" | |
| #--------------------------------------------------------------------------- | |
| .686: | |
| #.MODEL flat,C | |
| .code: | |
| #--------------------------------------------------------------------------- | |
| .globl ASM_PFX(RShiftU64) | |
| #UINT64 | |
| #RShiftU64 ( | |
| # IN UINT64 Operand, | |
| # IN UINTN Count | |
| # ) | |
| #/*++ | |
| # | |
| #Routine Description: | |
| # This routine allows a 64 bit value to be right shifted by 32 bits and returns the | |
| # shifted value. | |
| # Count is valid up 63. (Only Bits 0-5 is valid for Count) | |
| #Arguments: | |
| # Operand - Value to be shifted | |
| # Count - Number of times to shift right. | |
| # | |
| #Returns: | |
| # | |
| # Value shifted right identified by the Count. | |
| # | |
| #--*/ | |
| ASM_PFX(RShiftU64): | |
| movl 4(%esp), %eax # dword ptr Operand[0] | |
| movl 8(%esp), %edx # dword ptr Operand[4] | |
| # | |
| # CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EDX is not touched | |
| # For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later. | |
| # | |
| movl 0xC(%esp), %ecx # Count | |
| andl $63, %ecx | |
| shrd %cl, %edx, %eax | |
| shrb %cl, %edx | |
| cmpl $32, %ecx | |
| jc _RShiftU64_Done | |
| # | |
| # Since Count is 32 - 63, edx will have been shifted by 0 - 31 | |
| # If shifted by 32 or more, set upper 32 bits to zero. | |
| # | |
| movl %edx, %eax | |
| xorl %edx, %edx | |
| _RShiftU64_Done: | |
| ret | |
| #RShiftU64 ENDP | |