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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:
LShiftU64.c
Abstract:
64-bit left shift function for IA-32
--*/
#include "Tiano.h"
UINT64
LShiftU64 (
IN UINT64 Operand,
IN UINTN Count
)
/*++
Routine Description:
This routine allows a 64 bit value to be left 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 left.
Returns:
Value shifted left identified by the Count.
--*/
{
__asm {
mov eax, dword ptr Operand[0]
mov edx, dword ptr Operand[4]
;
; CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EAX is not touched
; For CL of 32 - 63, it will be shifted 0 - 31 so we will move eax to edx later.
;
mov ecx, Count
and ecx, 63
shld edx, eax, cl
shl eax, cl
;
; Since Count is 32 - 63, eax will have been shifted by 0 - 31
; If shifted by 32 or more, set lower 32 bits to zero.
;
cmp ecx, 32
jc short _LShiftU64_Done
mov edx, eax
xor eax, eax
_LShiftU64_Done:
}
}
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