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Diffstat (limited to 'EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.S')
| -rw-r--r-- | EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.S | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.S b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.S new file mode 100644 index 0000000000..7eba91298a --- /dev/null +++ b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/RShiftU64.S @@ -0,0 +1,80 @@ +#/*++ +# +#Copyright (c) 2006, Intel Corporation +#All rights reserved. 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 + |