1/* Optimized strcpy implementation for PowerPC476.
2   Copyright (C) 2010-2021 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/* strcpy
22
23       Register Use
24       r3:destination and return address
25       r4:source address
26       r10:temp destination address
27
28       Implementation description
29       Loop by checking 2 words at a time, with dlmzb. Check if there is a null
30       in the 2 words. If there is a null jump to end checking to determine
31       where in the last 8 bytes it is. Copy the appropriate bytes of the last
32       8 according to the null position. */
33
34EALIGN (strcpy, 5, 0)
35       neg     r7,r4
36       subi    r4,r4,1
37       clrlwi. r8,r7,29
38       subi    r10,r3,1
39       beq     L(pre_word8_loop)
40       mtctr   r8
41
42L(loop):
43       lbzu    r5,0x01(r4)
44       cmpi    cr5,r5,0x0
45       stbu    r5,0x01(r10)
46       beq     cr5,L(end_strcpy)
47       bdnz    L(loop)
48
49L(pre_word8_loop):
50       subi    r4,r4,3
51       subi    r10,r10,3
52
53L(word8_loop):
54       lwzu    r5,0x04(r4)
55       lwzu    r6,0x04(r4)
56       dlmzb.  r11,r5,r6
57       bne     L(byte_copy)
58       stwu    r5,0x04(r10)
59       stwu    r6,0x04(r10)
60       lwzu    r5,0x04(r4)
61       lwzu    r6,0x04(r4)
62       dlmzb.  r11,r5,r6
63       bne     L(byte_copy)
64       stwu    r5,0x04(r10)
65       stwu    r6,0x04(r10)
66       lwzu    r5,0x04(r4)
67       lwzu    r6,0x04(r4)
68       dlmzb.  r11,r5,r6
69       bne     L(byte_copy)
70       stwu    r5,0x04(r10)
71       stwu    r6,0x04(r10)
72       lwzu    r5,0x04(r4)
73       lwzu    r6,0x04(r4)
74       dlmzb.  r11,r5,r6
75       bne     L(byte_copy)
76       stwu    r5,0x04(r10)
77       stwu    r6,0x04(r10)
78       b       L(word8_loop)
79
80L(last_bytes_copy):
81       stwu    r5,0x04(r10)
82       subi    r11,r11,4
83       mtctr   r11
84       addi    r10,r10,3
85       subi    r4,r4,1
86
87L(last_bytes_copy_loop):
88       lbzu    r5,0x01(r4)
89       stbu    r5,0x01(r10)
90       bdnz    L(last_bytes_copy_loop)
91       blr
92
93L(byte_copy):
94       blt     L(last_bytes_copy)
95       mtctr   r11
96       addi    r10,r10,3
97       subi    r4,r4,5
98
99L(last_bytes_copy_loop2):
100       lbzu    r5,0x01(r4)
101       stbu    r5,0x01(r10)
102       bdnz    L(last_bytes_copy_loop2)
103
104L(end_strcpy):
105       blr
106END (strcpy)
107libc_hidden_builtin_def (strcpy)
108