1/* Optimized strcpy implementation for PowerPC.
2   Copyright (C) 1997-2021 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4
5   The GNU C Library is free software; you can redistribute it and/or
6   modify it under the terms of the GNU Lesser General Public
7   License as published by the Free Software Foundation; either
8   version 2.1 of the License, or (at your option) any later version.
9
10   The GNU C Library is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public
16   License along with the GNU C Library; if not, see
17   <https://www.gnu.org/licenses/>.  */
18
19#include <sysdep.h>
20
21/* See strlen.s for comments on how the end-of-string testing works.  */
22
23/* char * [r3] strcpy (char *dest [r3], const char *src [r4])  */
24
25EALIGN (strcpy, 4, 0)
26
27#define rTMP	r0
28#define rRTN	r3	/* incoming DEST arg preserved as result */
29#define rSRC	r4	/* pointer to previous word in src */
30#define rDEST	r5	/* pointer to previous word in dest */
31#define rWORD	r6	/* current word from src */
32#define rFEFE	r7	/* constant 0xfefefeff (-0x01010101) */
33#define r7F7F	r8	/* constant 0x7f7f7f7f */
34#define rNEG	r9	/* ~(word in s1 | 0x7f7f7f7f) */
35#define rALT	r10	/* alternate word from src */
36
37
38	or	rTMP, rSRC, rRTN
39	clrlwi.	rTMP, rTMP, 30
40	addi	rDEST, rRTN, -4
41	bne	L(unaligned)
42
43	lis	rFEFE, -0x101
44	lis	r7F7F, 0x7f7f
45	lwz	rWORD, 0(rSRC)
46	addi	rFEFE, rFEFE, -0x101
47	addi	r7F7F, r7F7F, 0x7f7f
48	b	L(g2)
49
50L(g0):	lwzu	rALT, 4(rSRC)
51	stwu	rWORD, 4(rDEST)
52	add	rTMP, rFEFE, rALT
53	nor	rNEG, r7F7F, rALT
54	and.	rTMP, rTMP, rNEG
55	bne-	L(g1)
56	lwzu	rWORD, 4(rSRC)
57	stwu	rALT, 4(rDEST)
58L(g2):	add	rTMP, rFEFE, rWORD
59	nor	rNEG, r7F7F, rWORD
60	and.	rTMP, rTMP, rNEG
61	beq+	L(g0)
62
63	mr	rALT, rWORD
64/* We've hit the end of the string.  Do the rest byte-by-byte.  */
65L(g1):
66#ifdef __LITTLE_ENDIAN__
67	rlwinm.	rTMP, rALT, 0, 24, 31
68	stb	rALT, 4(rDEST)
69	beqlr-
70	rlwinm.	rTMP, rALT, 24, 24, 31
71	stb	rTMP, 5(rDEST)
72	beqlr-
73	rlwinm.	rTMP, rALT, 16, 24, 31
74	stb	rTMP, 6(rDEST)
75	beqlr-
76	rlwinm	rTMP, rALT, 8, 24, 31
77	stb	rTMP, 7(rDEST)
78	blr
79#else
80	rlwinm.	rTMP, rALT, 8, 24, 31
81	stb	rTMP, 4(rDEST)
82	beqlr-
83	rlwinm.	rTMP, rALT, 16, 24, 31
84	stb	rTMP, 5(rDEST)
85	beqlr-
86	rlwinm.	rTMP, rALT, 24, 24, 31
87	stb	rTMP, 6(rDEST)
88	beqlr-
89	stb	rALT, 7(rDEST)
90	blr
91#endif
92
93/* Oh well.  In this case, we just do a byte-by-byte copy.  */
94	.align 4
95	nop
96L(unaligned):
97	lbz	rWORD, 0(rSRC)
98	addi	rDEST, rRTN, -1
99	cmpwi	rWORD, 0
100	beq-	L(u2)
101
102L(u0):	lbzu	rALT, 1(rSRC)
103	stbu	rWORD, 1(rDEST)
104	cmpwi	rALT, 0
105	beq-	L(u1)
106	nop		/* Let 601 load start of loop.  */
107	lbzu	rWORD, 1(rSRC)
108	stbu	rALT, 1(rDEST)
109	cmpwi	rWORD, 0
110	bne+	L(u0)
111L(u2):	stb	rWORD, 1(rDEST)
112	blr
113L(u1):	stb	rALT, 1(rDEST)
114	blr
115
116END (strcpy)
117libc_hidden_builtin_def (strcpy)
118