[mirror_edk2.git] / MdePkg / Library / BaseMemoryLibRepStr / X64 / IsZeroBuffer.nasm

;------------------------------------------------------------------------------\r
;\r
; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>\r
; 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
;   IsZeroBuffer.nasm\r
;\r
; Abstract:\r
;\r
;   IsZeroBuffer function\r
;\r
; Notes:\r
;\r
;------------------------------------------------------------------------------\r
\r
    DEFAULT REL\r
    SECTION .text\r
\r
;------------------------------------------------------------------------------\r
;  BOOLEAN\r
;  EFIAPI\r
;  InternalMemIsZeroBuffer (\r
;    IN CONST VOID  *Buffer,\r
;    IN UINTN       Length\r
;    );\r
;------------------------------------------------------------------------------\r
global ASM_PFX(InternalMemIsZeroBuffer)\r
ASM_PFX(InternalMemIsZeroBuffer):\r
    push    rdi\r
    mov     rdi, rcx                   ; rdi <- Buffer\r
    mov     rcx, rdx                   ; rcx <- Length\r
    shr     rcx, 3                     ; rcx <- number of qwords\r
    and     rdx, 7                     ; rdx <- number of trailing bytes\r
    xor     rax, rax                   ; rax <- 0, also set ZF\r
    repe    scasq\r
    jnz     @ReturnFalse               ; ZF=0 means non-zero element found\r
    mov     rcx, rdx\r
    repe    scasb\r
    jnz     @ReturnFalse\r
    pop     rdi\r
    mov     rax, 1                     ; return TRUE\r
    ret\r
@ReturnFalse:\r
    pop     rdi\r
    xor     rax, rax\r
    ret                                ; return FALSE\r
\r
Commit	Line	Data
02b5cf7f HW	1	;------------------------------------------------------------------------------\r
	2	;\r
	3	; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>\r
	4	; 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	; IsZeroBuffer.nasm\r
	15	;\r
	16	; Abstract:\r
	17	;\r
	18	; IsZeroBuffer function\r
	19	;\r
	20	; Notes:\r
	21	;\r
	22	;------------------------------------------------------------------------------\r
	23	\r
	24	DEFAULT REL\r
	25	SECTION .text\r
	26	\r
	27	;------------------------------------------------------------------------------\r
	28	; BOOLEAN\r
	29	; EFIAPI\r
	30	; InternalMemIsZeroBuffer (\r
	31	; IN CONST VOID *Buffer,\r
	32	; IN UINTN Length\r
	33	; );\r
	34	;------------------------------------------------------------------------------\r
	35	global ASM_PFX(InternalMemIsZeroBuffer)\r
	36	ASM_PFX(InternalMemIsZeroBuffer):\r
	37	push rdi\r
	38	mov rdi, rcx ; rdi <- Buffer\r
	39	mov rcx, rdx ; rcx <- Length\r
	40	shr rcx, 3 ; rcx <- number of qwords\r
	41	and rdx, 7 ; rdx <- number of trailing bytes\r
	42	xor rax, rax ; rax <- 0, also set ZF\r
	43	repe scasq\r
	44	jnz @ReturnFalse ; ZF=0 means non-zero element found\r
	45	mov rcx, rdx\r
	46	repe scasb\r
	47	jnz @ReturnFalse\r
	48	pop rdi\r
	49	mov rax, 1 ; return TRUE\r
	50	ret\r
	51	@ReturnFalse:\r
	52	pop rdi\r
	53	xor rax, rax\r
	54	ret ; return FALSE\r
	55	\r