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