mirror of https://github.com/acidanthera/audk.git
72 lines
1.9 KiB
C
72 lines
1.9 KiB
C
/*++
|
|
|
|
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"
|
|
|
|
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 {
|
|
|
|
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 EDX is not touched
|
|
; For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later.
|
|
;
|
|
mov ecx, Count
|
|
and ecx, 63
|
|
shrd eax, edx, cl
|
|
shr edx, cl
|
|
|
|
cmp ecx, 32
|
|
jc short _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.
|
|
;
|
|
mov eax, edx
|
|
xor edx, edx
|
|
|
|
_RShiftU64_Done:
|
|
}
|
|
}
|