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#/*++
#
#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
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