1 /** @file
2 AsmWriteDr4 function
3
4 Copyright (c) 2006 - 2008, 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 Writes a value to Debug Register 4 (DR4).
17
18 Writes and returns a new value to DR4. This function is only available on
19 IA-32 and x64. This writes a 32-bit value on IA-32 and a 64-bit value on x64.
20
21 @param Value The value to write to Dr4.
22
23 @return The value written to Debug Register 4 (DR4).
24
25 **/
26 UINTN
27 EFIAPI
AsmWriteDr4(IN UINTN Value)28 AsmWriteDr4 (
29 IN UINTN Value
30 )
31 {
32 _asm {
33 mov eax, Value
34 _emit 0x0f // mov dr4, eax
35 _emit 0x23
36 _emit 0xe0
37 }
38 }
39
40