[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / EdkIIGlueLib / Library / BaseLib / Ia32 / ReadDr4.asm

; Copyright (c) 2004, 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
3eb9473e	1	; Copyright (c) 2004, Intel Corporation \r
	2	; All rights reserved. This program and the accompanying materials \r
	3	; are licensed and made available under the terms and conditions of the BSD License \r
	4	; which accompanies this distribution. The full text of the license may be found at \r
	5	; http://opensource.org/licenses/bsd-license.php \r
	6	; \r
	7	; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r
	8	; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r
	9	;\r
	10	; Module Name:\r
	11	;\r
	12	; ReadDr4.Asm\r
	13	;\r
	14	; Abstract:\r
	15	;\r
	16	; AsmReadDr4 function\r
	17	;\r
	18	; Notes:\r
	19	;\r
	20	;------------------------------------------------------------------------------\r
	21	\r
	22	.586p\r
	23	.model flat,C\r
	24	.code\r
	25	\r
	26	;------------------------------------------------------------------------------\r
	27	; UINTN\r
	28	; EFIAPI\r
	29	; AsmReadDr4 (\r
	30	; VOID\r
	31	; );\r
	32	;------------------------------------------------------------------------------\r
	33	AsmReadDr4 PROC\r
	34	;\r
	35	; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading\r
	36	; this register will cause a #UD exception.\r
	37	;\r
	38	; MS assembler doesn't support this instruction since no one would use it\r
	39	; under normal circustances. Here opcode is used.\r
	40	;\r
	41	DB 0fh, 21h, 0e0h\r
	42	ret\r
	43	AsmReadDr4 ENDP\r
	44	\r
	45	END\r