1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Based on linux/arch/arm/lib/memset.S
*
* ASM optimised string functions
*/
#include <arch/asm.h>
#include "asmlib.h"
ENTRY(memset)
ands r3, r0, #3 @ 1 unaligned?
mov ip, r0 @ preserve r0 as return value
bne 6f @ 1
/*
* we know that the pointer in ip is aligned to a word boundary.
*/
1: orr r1, r1, r1, lsl #8
orr r1, r1, r1, lsl #16
mov r3, r1
cmp r2, #16
blt 4f
#if ! CALGN(1)+0
/*
* We need 2 extra registers for this loop - use r8 and the LR
*/
stmfd sp!, {r8, lr}
mov r8, r1
mov lr, r1
2: subs r2, r2, #64
stmgeia ip!, {r1, r3, r8, lr} @ 64 bytes at a time.
stmgeia ip!, {r1, r3, r8, lr}
stmgeia ip!, {r1, r3, r8, lr}
stmgeia ip!, {r1, r3, r8, lr}
bgt 2b
ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go.
/*
* No need to correct the count; we're only testing bits from now on
*/
tst r2, #32
stmneia ip!, {r1, r3, r8, lr}
stmneia ip!, {r1, r3, r8, lr}
tst r2, #16
stmneia ip!, {r1, r3, r8, lr}
ldmfd sp!, {r8, lr}
#else
/*
* This version aligns the destination pointer in order to write
* whole cache lines at once.
*/
stmfd sp!, {r4-r8, lr}
mov r4, r1
mov r5, r1
mov r6, r1
mov r7, r1
mov r8, r1
mov lr, r1
cmp r2, #96
tstgt ip, #31
ble 3f
and r8, ip, #31
rsb r8, r8, #32
sub r2, r2, r8
movs r8, r8, lsl #(32 - 4)
stmcsia ip!, {r4, r5, r6, r7}
stmmiia ip!, {r4, r5}
tst r8, #(1 << 30)
mov r8, r1
strne r1, [ip], #4
3: subs r2, r2, #64
stmgeia ip!, {r1, r3-r8, lr}
stmgeia ip!, {r1, r3-r8, lr}
bgt 3b
ldmeqfd sp!, {r4-r8, pc}
tst r2, #32
stmneia ip!, {r1, r3-r8, lr}
tst r2, #16
stmneia ip!, {r4-r7}
ldmfd sp!, {r4-r8, lr}
#endif
4: tst r2, #8
stmneia ip!, {r1, r3}
tst r2, #4
strne r1, [ip], #4
/*
* When we get here, we've got less than 4 bytes to zero. We
* may have an unaligned pointer as well.
*/
5: tst r2, #2
strneb r1, [ip], #1
strneb r1, [ip], #1
tst r2, #1
strneb r1, [ip], #1
mov pc, lr
6: subs r2, r2, #4 @ 1 do we have enough
blt 5b @ 1 bytes to align with?
cmp r3, #2 @ 1
strltb r1, [ip], #1 @ 1
strleb r1, [ip], #1 @ 1
strb r1, [ip], #1 @ 1
add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
b 1b
ENDPROC(memset)
|
