[mirror_edk2.git] / OldMdePkg / Library / BaseLib / Ia32 / ReadDr4.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
;   ReadDr4.Asm\r
;\r
; Abstract:\r
;\r
;   AsmReadDr4 function\r
;\r
; Notes:\r
;\r
;------------------------------------------------------------------------------\r
\r
    .586p\r
    .model  flat,C\r
    .code\r
\r
;------------------------------------------------------------------------------\r
; UINTN\r
; EFIAPI\r
; AsmReadDr4 (\r
;   VOID\r
;   );\r
;------------------------------------------------------------------------------\r
AsmReadDr4  PROC\r
    ;\r
    ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading\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, 21h, 0e0h\r
    ret\r
AsmReadDr4  ENDP\r
\r
    END\r
Commit	Line	Data
878ddf1f	1	;------------------------------------------------------------------------------\r
	2	;\r
	3	; Copyright (c) 2006, Intel Corporation\r
	4	; All rights reserved. This program and the accompanying materials\r
	5	; are licensed and made available under the terms and conditions of the BSD License\r
	6	; which accompanies this distribution. The full text of the license may be found at\r
	7	; http://opensource.org/licenses/bsd-license.php\r
	8	;\r
	9	; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	10	; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	11	;\r
	12	; Module Name:\r
	13	;\r
	14	; ReadDr4.Asm\r
	15	;\r
	16	; Abstract:\r
	17	;\r
	18	; AsmReadDr4 function\r
	19	;\r
	20	; Notes:\r
	21	;\r
	22	;------------------------------------------------------------------------------\r
	23	\r
	24	.586p\r
3f566587	25	.model flat,C\r
878ddf1f	26	.code\r
	27	\r
	28	;------------------------------------------------------------------------------\r
	29	; UINTN\r
	30	; EFIAPI\r
	31	; AsmReadDr4 (\r
	32	; VOID\r
	33	; );\r
	34	;------------------------------------------------------------------------------\r
3f566587	35	AsmReadDr4 PROC\r
a9a812a0	36	;\r
	37	; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading\r
	38	; this register will cause a #UD exception.\r
	39	;\r
	40	; MS assembler doesn't support this instruction since no one would use it\r
	41	; under normal circustances. Here opcode is used.\r
	42	;\r
878ddf1f	43	DB 0fh, 21h, 0e0h\r
878ddf1f	44	ret\r
3f566587	45	AsmReadDr4 ENDP\r
878ddf1f	46	\r
878ddf1f	47	END\r