Moved the MdePkg to OldMdePkg so that new code in MdePkg does not break existing...

[mirror_edk2.git] / OldMdePkg / Library / BaseLib / Ia32 / WriteDr4.asm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2006, Intel Corporation\r
; All rights reserved. This program and the accompanying materials\r
; are licensed and made available under the terms and conditions of the BSD License\r
; which accompanies this distribution.  The full text of the license may be found at\r
; http://opensource.org/licenses/bsd-license.php\r
;\r
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
;\r
; Module Name:\r
;\r
;   WriteDr4.Asm\r
;\r
; Abstract:\r
;\r
;   AsmWriteDr4 function\r
;\r
; Notes:\r
;\r
;------------------------------------------------------------------------------\r
\r
    .586p\r
    .model  flat,C\r
    .code\r
\r
;------------------------------------------------------------------------------\r
; UINTN\r
; EFIAPI\r
; AsmWriteDr4 (\r
;   IN UINTN Value\r
;   );\r
;------------------------------------------------------------------------------\r
AsmWriteDr4 PROC\r
    mov     eax, [esp + 4]\r
    ;\r
    ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, writing to\r
    ; this register will cause a #UD exception.\r
    ;\r
    ; MS assembler doesn't support this instruction since no one would use it\r
    ; under normal circustances. Here opcode is used.\r
    ;\r
    DB      0fh, 23h, 0e0h\r
    ret\r
AsmWriteDr4 ENDP\r
\r
    END\r