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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm/lib/csumpartial.S | |
3 | * | |
4 | * Copyright (C) 1995-1998 Russell King | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | #include <linux/linkage.h> | |
11 | #include <asm/assembler.h> | |
4dd1837d | 12 | #include <asm/export.h> |
1da177e4 LT |
13 | |
14 | .text | |
15 | ||
16 | /* | |
17 | * Function: __u32 csum_partial(const char *src, int len, __u32 sum) | |
18 | * Params : r0 = buffer, r1 = len, r2 = checksum | |
19 | * Returns : r0 = new checksum | |
20 | */ | |
21 | ||
22 | buf .req r0 | |
23 | len .req r1 | |
24 | sum .req r2 | |
25 | td0 .req r3 | |
26 | td1 .req r4 @ save before use | |
27 | td2 .req r5 @ save before use | |
28 | td3 .req lr | |
29 | ||
8adbb371 | 30 | .Lzero: mov r0, sum |
1da177e4 LT |
31 | add sp, sp, #4 |
32 | ldr pc, [sp], #4 | |
33 | ||
34 | /* | |
35 | * Handle 0 to 7 bytes, with any alignment of source and | |
36 | * destination pointers. Note that when we get here, C = 0 | |
37 | */ | |
8adbb371 NP |
38 | .Lless8: teq len, #0 @ check for zero count |
39 | beq .Lzero | |
1da177e4 LT |
40 | |
41 | /* we must have at least one byte. */ | |
42 | tst buf, #1 @ odd address? | |
af36bef0 | 43 | movne sum, sum, ror #8 |
1da177e4 LT |
44 | ldrneb td0, [buf], #1 |
45 | subne len, len, #1 | |
46 | adcnes sum, sum, td0, put_byte_1 | |
47 | ||
8adbb371 NP |
48 | .Lless4: tst len, #6 |
49 | beq .Lless8_byte | |
1da177e4 LT |
50 | |
51 | /* we are now half-word aligned */ | |
52 | ||
8adbb371 | 53 | .Lless8_wordlp: |
1da177e4 LT |
54 | #if __LINUX_ARM_ARCH__ >= 4 |
55 | ldrh td0, [buf], #2 | |
56 | sub len, len, #2 | |
57 | #else | |
58 | ldrb td0, [buf], #1 | |
59 | ldrb td3, [buf], #1 | |
60 | sub len, len, #2 | |
61 | #ifndef __ARMEB__ | |
62 | orr td0, td0, td3, lsl #8 | |
63 | #else | |
64 | orr td0, td3, td0, lsl #8 | |
65 | #endif | |
66 | #endif | |
67 | adcs sum, sum, td0 | |
68 | tst len, #6 | |
8adbb371 | 69 | bne .Lless8_wordlp |
1da177e4 | 70 | |
8adbb371 | 71 | .Lless8_byte: tst len, #1 @ odd number of bytes |
1da177e4 LT |
72 | ldrneb td0, [buf], #1 @ include last byte |
73 | adcnes sum, sum, td0, put_byte_0 @ update checksum | |
74 | ||
8adbb371 | 75 | .Ldone: adc r0, sum, #0 @ collect up the last carry |
1da177e4 LT |
76 | ldr td0, [sp], #4 |
77 | tst td0, #1 @ check buffer alignment | |
78 | movne r0, r0, ror #8 @ rotate checksum by 8 bits | |
79 | ldr pc, [sp], #4 @ return | |
80 | ||
8adbb371 | 81 | .Lnot_aligned: tst buf, #1 @ odd address |
1da177e4 LT |
82 | ldrneb td0, [buf], #1 @ make even |
83 | subne len, len, #1 | |
84 | adcnes sum, sum, td0, put_byte_1 @ update checksum | |
85 | ||
86 | tst buf, #2 @ 32-bit aligned? | |
87 | #if __LINUX_ARM_ARCH__ >= 4 | |
88 | ldrneh td0, [buf], #2 @ make 32-bit aligned | |
89 | subne len, len, #2 | |
90 | #else | |
91 | ldrneb td0, [buf], #1 | |
92 | ldrneb ip, [buf], #1 | |
93 | subne len, len, #2 | |
94 | #ifndef __ARMEB__ | |
95 | orrne td0, td0, ip, lsl #8 | |
96 | #else | |
97 | orrne td0, ip, td0, lsl #8 | |
98 | #endif | |
99 | #endif | |
100 | adcnes sum, sum, td0 @ update checksum | |
6ebbf2ce | 101 | ret lr |
1da177e4 LT |
102 | |
103 | ENTRY(csum_partial) | |
104 | stmfd sp!, {buf, lr} | |
105 | cmp len, #8 @ Ensure that we have at least | |
8adbb371 | 106 | blo .Lless8 @ 8 bytes to copy. |
1da177e4 | 107 | |
af36bef0 RK |
108 | tst buf, #1 |
109 | movne sum, sum, ror #8 | |
110 | ||
1da177e4 LT |
111 | adds sum, sum, #0 @ C = 0 |
112 | tst buf, #3 @ Test destination alignment | |
8adbb371 | 113 | blne .Lnot_aligned @ align destination, return here |
1da177e4 LT |
114 | |
115 | 1: bics ip, len, #31 | |
116 | beq 3f | |
117 | ||
118 | stmfd sp!, {r4 - r5} | |
119 | 2: ldmia buf!, {td0, td1, td2, td3} | |
120 | adcs sum, sum, td0 | |
121 | adcs sum, sum, td1 | |
122 | adcs sum, sum, td2 | |
123 | adcs sum, sum, td3 | |
124 | ldmia buf!, {td0, td1, td2, td3} | |
125 | adcs sum, sum, td0 | |
126 | adcs sum, sum, td1 | |
127 | adcs sum, sum, td2 | |
128 | adcs sum, sum, td3 | |
129 | sub ip, ip, #32 | |
130 | teq ip, #0 | |
131 | bne 2b | |
132 | ldmfd sp!, {r4 - r5} | |
133 | ||
134 | 3: tst len, #0x1c @ should not change C | |
8adbb371 | 135 | beq .Lless4 |
1da177e4 LT |
136 | |
137 | 4: ldr td0, [buf], #4 | |
138 | sub len, len, #4 | |
139 | adcs sum, sum, td0 | |
140 | tst len, #0x1c | |
141 | bne 4b | |
8adbb371 | 142 | b .Lless4 |
93ed3970 | 143 | ENDPROC(csum_partial) |
4dd1837d | 144 | EXPORT_SYMBOL(csum_partial) |