[mirror_edk2.git] / MdePkg / Library / BaseMemoryLibRepStr / Ia32 / 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
    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    edi\r
    mov     edi, [esp + 8]             ; edi <- Buffer\r
    mov     ecx, [esp + 12]            ; ecx <- Length\r
    mov     edx, ecx                   ; edx <- ecx\r
    shr     ecx, 2                     ; ecx <- number of dwords\r
    and     edx, 3                     ; edx <- number of trailing bytes\r
    xor     eax, eax                   ; eax <- 0, also set ZF\r
    repe    scasd\r
    jnz     @ReturnFalse               ; ZF=0 means non-zero element found\r
    mov     ecx, edx\r
    repe    scasb\r
    jnz     @ReturnFalse\r
    pop     edi\r
    mov     eax, 1                     ; return TRUE\r
    ret\r
@ReturnFalse:\r
    pop     edi\r
    xor     eax, eax\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	SECTION .text\r
	25	\r
	26	;------------------------------------------------------------------------------\r
	27	; BOOLEAN\r
	28	; EFIAPI\r
	29	; InternalMemIsZeroBuffer (\r
	30	; IN CONST VOID *Buffer,\r
	31	; IN UINTN Length\r
	32	; );\r
	33	;------------------------------------------------------------------------------\r
	34	global ASM_PFX(InternalMemIsZeroBuffer)\r
	35	ASM_PFX(InternalMemIsZeroBuffer):\r
	36	push edi\r
	37	mov edi, [esp + 8] ; edi <- Buffer\r
	38	mov ecx, [esp + 12] ; ecx <- Length\r
	39	mov edx, ecx ; edx <- ecx\r
	40	shr ecx, 2 ; ecx <- number of dwords\r
	41	and edx, 3 ; edx <- number of trailing bytes\r
	42	xor eax, eax ; eax <- 0, also set ZF\r
	43	repe scasd\r
	44	jnz @ReturnFalse ; ZF=0 means non-zero element found\r
	45	mov ecx, edx\r
	46	repe scasb\r
	47	jnz @ReturnFalse\r
	48	pop edi\r
	49	mov eax, 1 ; return TRUE\r
	50	ret\r
	51	@ReturnFalse:\r
	52	pop edi\r
	53	xor eax, eax\r
	54	ret ; return FALSE\r
	55	\r