xref: /openbmc/linux/arch/arc/lib/strcpy-700.S (revision 2891f2d5)
1/*
2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9/* If dst and src are 4 byte aligned, copy 8 bytes at a time.
10   If the src is 4, but not 8 byte aligned, we first read 4 bytes to get
11   it 8 byte aligned.  Thus, we can do a little read-ahead, without
12   dereferencing a cache line that we should not touch.
13   Note that short and long instructions have been scheduled to avoid
14   branch stalls.
15   The beq_s to r3z could be made unaligned & long to avoid a stall
16   there, but the it is not likely to be taken often, and it
17   would also be likey to cost an unaligned mispredict at the next call.  */
18
19#include <linux/linkage.h>
20
21ENTRY_CFI(strcpy)
22	or	r2,r0,r1
23	bmsk_s	r2,r2,1
24	brne.d	r2,0,charloop
25	mov_s	r10,r0
26	ld_s	r3,[r1,0]
27	mov	r8,0x01010101
28	bbit0.d	r1,2,loop_start
29	ror	r12,r8
30	sub	r2,r3,r8
31	bic_s	r2,r2,r3
32	tst_s	r2,r12
33	bne	r3z
34	mov_s	r4,r3
35	.balign 4
36loop:
37	ld.a	r3,[r1,4]
38	st.ab	r4,[r10,4]
39loop_start:
40	ld.a	r4,[r1,4]
41	sub	r2,r3,r8
42	bic_s	r2,r2,r3
43	tst_s	r2,r12
44	bne_s	r3z
45	st.ab	r3,[r10,4]
46	sub	r2,r4,r8
47	bic	r2,r2,r4
48	tst	r2,r12
49	beq	loop
50	mov_s	r3,r4
51#ifdef __LITTLE_ENDIAN__
52r3z:	bmsk.f	r1,r3,7
53	lsr_s	r3,r3,8
54#else
55r3z:	lsr.f	r1,r3,24
56	asl_s	r3,r3,8
57#endif
58	bne.d	r3z
59	stb.ab	r1,[r10,1]
60	j_s	[blink]
61
62	.balign	4
63charloop:
64	ldb.ab	r3,[r1,1]
65
66
67	brne.d	r3,0,charloop
68	stb.ab	r3,[r10,1]
69	j	[blink]
70END_CFI(strcpy)
71