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 **/
31 UINT64
32 EFIAPI
InternalMathRShiftU64(IN UINT64 Operand,IN UINTN Count)33 InternalMathRShiftU64 (
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]
46 L0:
47     shrd    eax, edx, cl
48     shr     edx, cl
49   }
50 }
51 
52