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
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/*
* linux/arch/arm/lib/csumpartial.S
*
* Copyright (C) 1995-1998 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
.text
/*
* Function: __u32 csum_partial(const char *src, int len, __u32 sum)
* Params : r0 = buffer, r1 = len, r2 = checksum
* Returns : r0 = new checksum
*/
buf .req r0
len .req r1
sum .req r2
td0 .req r3
td1 .req r4 @ save before use
td2 .req r5 @ save before use
td3 .req lr
.zero: mov r0, sum
add sp, sp, #4
ldr pc, [sp], #4
/*
* Handle 0 to 7 bytes, with any alignment of source and
* destination pointers. Note that when we get here, C = 0
*/
.less8: teq len, #0 @ check for zero count
beq .zero
/* we must have at least one byte. */
tst buf, #1 @ odd address?
movne sum, sum, ror #8
ldrneb td0, [buf], #1
subne len, len, #1
adcnes sum, sum, td0, put_byte_1
.less4: tst len, #6
beq .less8_byte
/* we are now half-word aligned */
.less8_wordlp:
#if __LINUX_ARM_ARCH__ >= 4
ldrh td0, [buf], #2
sub len, len, #2
#else
ldrb td0, [buf], #1
ldrb td3, [buf], #1
sub len, len, #2
#ifndef __ARMEB__
orr td0, td0, td3, lsl #8
#else
orr td0, td3, td0, lsl #8
#endif
#endif
adcs sum, sum, td0
tst len, #6
bne .less8_wordlp
.less8_byte: tst len, #1 @ odd number of bytes
ldrneb td0, [buf], #1 @ include last byte
adcnes sum, sum, td0, put_byte_0 @ update checksum
.done: adc r0, sum, #0 @ collect up the last carry
ldr td0, [sp], #4
tst td0, #1 @ check buffer alignment
movne r0, r0, ror #8 @ rotate checksum by 8 bits
ldr pc, [sp], #4 @ return
.not_aligned: tst buf, #1 @ odd address
ldrneb td0, [buf], #1 @ make even
subne len, len, #1
adcnes sum, sum, td0, put_byte_1 @ update checksum
tst buf, #2 @ 32-bit aligned?
#if __LINUX_ARM_ARCH__ >= 4
ldrneh td0, [buf], #2 @ make 32-bit aligned
subne len, len, #2
#else
ldrneb td0, [buf], #1
ldrneb ip, [buf], #1
subne len, len, #2
#ifndef __ARMEB__
orrne td0, td0, ip, lsl #8
#else
orrne td0, ip, td0, lsl #8
#endif
#endif
adcnes sum, sum, td0 @ update checksum
mov pc, lr
ENTRY(csum_partial)
stmfd sp!, {buf, lr}
cmp len, #8 @ Ensure that we have at least
blo .less8 @ 8 bytes to copy.
tst buf, #1
movne sum, sum, ror #8
adds sum, sum, #0 @ C = 0
tst buf, #3 @ Test destination alignment
blne .not_aligned @ aligh destination, return here
1: bics ip, len, #31
beq 3f
stmfd sp!, {r4 - r5}
2: ldmia buf!, {td0, td1, td2, td3}
adcs sum, sum, td0
adcs sum, sum, td1
adcs sum, sum, td2
adcs sum, sum, td3
ldmia buf!, {td0, td1, td2, td3}
adcs sum, sum, td0
adcs sum, sum, td1
adcs sum, sum, td2
adcs sum, sum, td3
sub ip, ip, #32
teq ip, #0
bne 2b
ldmfd sp!, {r4 - r5}
3: tst len, #0x1c @ should not change C
beq .less4
4: ldr td0, [buf], #4
sub len, len, #4
adcs sum, sum, td0
tst len, #0x1c
bne 4b
b .less4
|
