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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/csky/abiv2/strlen.S
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/* SPDX-License-Identifier: GPL-2.0 */

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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

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#include <linux/linkage.h>

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#include "sysdep.h"

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ENTRY(strlen)

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	/* Check if the start addr is aligned.  */

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	mov	r3, r0

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	andi	r1, r0, 3

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	movi	r2, 4

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	movi	r0, 0

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	bnez	r1, .L_start_not_aligned

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	LABLE_ALIGN

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.L_start_addr_aligned:

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	/* Check if all the bytes in the word are not zero.  */

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	ldw	r1, (r3)

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 4)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 8)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 12)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 16)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 20)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 24)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	ldw	r1, (r3, 28)

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	addi	r0, 4

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	tstnbz	r1

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	bf	.L_string_tail

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	addi	r0, 4

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	addi	r3, 32

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	br	.L_start_addr_aligned

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.L_string_tail:

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# ifdef __CSKYBE__

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	xtrb0	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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	xtrb1	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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	xtrb2	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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# else

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	xtrb3	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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	xtrb2	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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	xtrb1	r3, r1

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	bez	r3, .L_return

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	addi	r0, 1

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# endif	/* !__CSKYBE__ */

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.L_return:

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	rts

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.L_start_not_aligned:

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	sub	r2, r2, r1

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.L_start_not_aligned_loop:

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	ldb	r1, (r3)

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	PRE_BNEZAD (r2)

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	addi	r3, 1

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	bez	r1, .L_return

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	addi	r0, 1

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	BNEZAD (r2, .L_start_not_aligned_loop)

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	br	.L_start_addr_aligned

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ENDPROC(strlen)

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