[mirror_edk2.git] / MdePkg / Library / BaseLib / Ia32 / ReadDr4.nasm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>\r
; SPDX-License-Identifier: BSD-2-Clause-Patent\r
;\r
; Module Name:\r
;\r
;   ReadDr4.Asm\r
;\r
; Abstract:\r
;\r
;   AsmReadDr4 function\r
;\r
; Notes:\r
;\r
;------------------------------------------------------------------------------\r
\r
    SECTION .text\r
\r
;------------------------------------------------------------------------------\r
; UINTN\r
; EFIAPI\r
; AsmReadDr4 (\r
;   VOID\r
;   );\r
;------------------------------------------------------------------------------\r
global ASM_PFX(AsmReadDr4)\r
ASM_PFX(AsmReadDr4):\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.\r
    ;\r
    mov     eax, dr4\r
    ret\r
\r
Commit	Line	Data
	1	;------------------------------------------------------------------------------\r
	2	;\r
	3	; Copyright (c) 2006 - 2022, Intel Corporation. All rights reserved.<BR>\r
	4	; SPDX-License-Identifier: BSD-2-Clause-Patent\r
	5	;\r
	6	; Module Name:\r
	7	;\r
	8	; ReadDr4.Asm\r
	9	;\r
	10	; Abstract:\r
	11	;\r
	12	; AsmReadDr4 function\r
	13	;\r
	14	; Notes:\r
	15	;\r
	16	;------------------------------------------------------------------------------\r
	17	\r
	18	SECTION .text\r
	19	\r
	20	;------------------------------------------------------------------------------\r
	21	; UINTN\r
	22	; EFIAPI\r
	23	; AsmReadDr4 (\r
	24	; VOID\r
	25	; );\r
	26	;------------------------------------------------------------------------------\r
	27	global ASM_PFX(AsmReadDr4)\r
	28	ASM_PFX(AsmReadDr4):\r
	29	;\r
	30	; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading\r
	31	; this register will cause a #UD exception.\r
	32	;\r
	33	; MS assembler doesn't support this instruction since no one would use it\r
	34	; under normal circustances.\r
	35	;\r
	36	mov eax, dr4\r
	37	ret\r
	38	\r