1/** @file
2  64-bit logical right shift function for IA-32
3
4  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
5  This program and the accompanying materials
6  are licensed and made available under the terms and conditions of the BSD License
7  which accompanies this distribution.  The full text of the license may be found at
8  http://opensource.org/licenses/bsd-license.php.
9
10  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13**/
14
15
16
17
18/**
19  Shifts a 64-bit integer right between 0 and 63 bits. This high bits
20  are filled with zeros. The shifted value is returned.
21
22  This function shifts the 64-bit value Operand to the right by Count bits. The
23  high Count bits are set to zero. The shifted value is returned.
24
25  @param  Operand The 64-bit operand to shift right.
26  @param  Count   The number of bits to shift right.
27
28  @return Operand >> Count
29
30**/
31UINT64
32EFIAPI
33InternalMathRShiftU64 (
34  IN      UINT64                    Operand,
35  IN      UINTN                     Count
36  )
37{
38  _asm {
39    mov     cl, byte ptr [Count]
40    xor     edx, edx
41    mov     eax, dword ptr [Operand + 4]
42    test    cl, 32
43    jnz     L0
44    mov     edx, eax
45    mov     eax, dword ptr [Operand + 0]
46L0:
47    shrd    eax, edx, cl
48    shr     edx, cl
49  }
50}
51
52