memset.S
2.27 KB
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
117
118
119
120
121
/* Optimised simple memory fill
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <asm/cache.h>
.section .text
.balign L1_CACHE_BYTES
###############################################################################
#
# void *memset(void *dst, int c, size_t n)
#
###############################################################################
.globl memset
.type memset,@function
memset:
movm [d2,d3],(sp)
mov d0,(12,sp)
mov d1,(16,sp)
mov (20,sp),d2 # count
mov d0,a0 # dst
mov d0,e3 # the return value
cmp +0,d2
beq memset_done # return if zero-length fill
# see if the region parameters are four-byte aligned
or d0,d2,d3
and +3,d3
bne memset_1 # jump if not
extbu d1
mov_asl d1,d3,8,d1
or_asl d1,d3,8,d1
or_asl d1,d3,8,d1
or d3,d1
# we want to transfer as much as we can in chunks of 32 bytes
cmp +31,d2
bls memset_4_remainder # 4-byte aligned remainder
add -32,d2
mov +32,d3
memset_4_loop:
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
sub d3,d2
bcc memset_4_loop
add d3,d2
beq memset_4_no_remainder
memset_4_remainder:
# cut 4-7 words down to 0-3
cmp +16,d2
bcs memset_4_three_or_fewer_words
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
add -16,d2
beq memset_4_no_remainder
# copy the remaining 1, 2 or 3 words
memset_4_three_or_fewer_words:
cmp +8,d2
bcs memset_4_one_word
beq memset_4_two_words
mov d1,(a0+)
memset_4_two_words:
mov d1,(a0+)
memset_4_one_word:
mov d1,(a0+)
memset_4_no_remainder:
# check we set the correct amount
# TODO: REMOVE CHECK
sub e3,a0,d2
mov (20,sp),d1
cmp d2,d1
beq memset_done
break
break
break
memset_done:
mov e3,a0
ret [d2,d3],8
# handle misaligned copying
memset_1:
add -1,d2
mov +1,d3
setlb # setlb requires the next insns
# to occupy exactly 4 bytes
sub d3,d2
movbu d1,(a0)
inc a0
lcc
mov e3,a0
ret [d2,d3],8
memset_end:
.size memset, memset_end-memset