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
| /* SPDX-License-Identifier: GPL-2.0-only */
| /*
| * linux/arch/arm/lib/csumpartial.S
| *
| * Copyright (C) 1995-1998 Russell King
| */
| #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
|
| .Lzero: 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
| */
| .Lless8: teq len, #0 @ check for zero count
| beq .Lzero
|
| /* we must have at least one byte. */
| tst buf, #1 @ odd address?
| movne sum, sum, ror #8
| ldrbne td0, [buf], #1
| subne len, len, #1
| adcsne sum, sum, td0, put_byte_1
|
| .Lless4: tst len, #6
| beq .Lless8_byte
|
| /* we are now half-word aligned */
|
| .Lless8_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 .Lless8_wordlp
|
| .Lless8_byte: tst len, #1 @ odd number of bytes
| ldrbne td0, [buf], #1 @ include last byte
| adcsne sum, sum, td0, put_byte_0 @ update checksum
|
| .Ldone: 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
|
| .Lnot_aligned: tst buf, #1 @ odd address
| ldrbne td0, [buf], #1 @ make even
| subne len, len, #1
| adcsne sum, sum, td0, put_byte_1 @ update checksum
|
| tst buf, #2 @ 32-bit aligned?
| #if __LINUX_ARM_ARCH__ >= 4
| ldrhne td0, [buf], #2 @ make 32-bit aligned
| subne len, len, #2
| #else
| ldrbne td0, [buf], #1
| ldrbne ip, [buf], #1
| subne len, len, #2
| #ifndef __ARMEB__
| orrne td0, td0, ip, lsl #8
| #else
| orrne td0, ip, td0, lsl #8
| #endif
| #endif
| adcsne sum, sum, td0 @ update checksum
| ret lr
|
| ENTRY(csum_partial)
| stmfd sp!, {buf, lr}
| cmp len, #8 @ Ensure that we have at least
| blo .Lless8 @ 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 .Lnot_aligned @ align 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 .Lless4
|
| 4: ldr td0, [buf], #4
| sub len, len, #4
| adcs sum, sum, td0
| tst len, #0x1c
| bne 4b
| b .Lless4
| ENDPROC(csum_partial)
|
|
