xref: /openbmc/linux/arch/arc/lib/strcpy-700.S (revision 6c33a6f4)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 */
5
6/* If dst and src are 4 byte aligned, copy 8 bytes at a time.
7   If the src is 4, but not 8 byte aligned, we first read 4 bytes to get
8   it 8 byte aligned.  Thus, we can do a little read-ahead, without
9   dereferencing a cache line that we should not touch.
10   Note that short and long instructions have been scheduled to avoid
11   branch stalls.
12   The beq_s to r3z could be made unaligned & long to avoid a stall
13   there, but the it is not likely to be taken often, and it
14   would also be likey to cost an unaligned mispredict at the next call.  */
15
16#include <linux/linkage.h>
17
18ENTRY_CFI(strcpy)
19	or	r2,r0,r1
20	bmsk_s	r2,r2,1
21	brne.d	r2,0,charloop
22	mov_s	r10,r0
23	ld_s	r3,[r1,0]
24	mov	r8,0x01010101
25	bbit0.d	r1,2,loop_start
26	ror	r12,r8
27	sub	r2,r3,r8
28	bic_s	r2,r2,r3
29	tst_s	r2,r12
30	bne	r3z
31	mov_s	r4,r3
32	.balign 4
33loop:
34	ld.a	r3,[r1,4]
35	st.ab	r4,[r10,4]
36loop_start:
37	ld.a	r4,[r1,4]
38	sub	r2,r3,r8
39	bic_s	r2,r2,r3
40	tst_s	r2,r12
41	bne_s	r3z
42	st.ab	r3,[r10,4]
43	sub	r2,r4,r8
44	bic	r2,r2,r4
45	tst	r2,r12
46	beq	loop
47	mov_s	r3,r4
48#ifdef __LITTLE_ENDIAN__
49r3z:	bmsk.f	r1,r3,7
50	lsr_s	r3,r3,8
51#else
52r3z:	lsr.f	r1,r3,24
53	asl_s	r3,r3,8
54#endif
55	bne.d	r3z
56	stb.ab	r1,[r10,1]
57	j_s	[blink]
58
59	.balign	4
60charloop:
61	ldb.ab	r3,[r1,1]
62
63
64	brne.d	r3,0,charloop
65	stb.ab	r3,[r10,1]
66	j	[blink]
67END_CFI(strcpy)
68