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1 | /* |
2 | * Network Checksum & Copy routine |
3 | * |
4 | * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co |
5 | * Stephane Eranian <eranian@hpl.hp.com> |
6 | * |
7 | * Most of the code has been imported from Linux/Alpha |
8 | */ |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/types.h> |
12 | #include <linux/string.h> |
13 | |
14 | #include <asm/uaccess.h> |
15 | |
16 | /* |
17 | * XXX Fixme: those 2 inlines are meant for debugging and will go away |
18 | */ |
19 | static inline unsigned |
20 | short from64to16(unsigned long x) |
21 | { |
22 | /* add up 32-bit words for 33 bits */ |
23 | x = (x & 0xffffffff) + (x >> 32); |
24 | /* add up 16-bit and 17-bit words for 17+c bits */ |
25 | x = (x & 0xffff) + (x >> 16); |
26 | /* add up 16-bit and 2-bit for 16+c bit */ |
27 | x = (x & 0xffff) + (x >> 16); |
28 | /* add up carry.. */ |
29 | x = (x & 0xffff) + (x >> 16); |
30 | return x; |
31 | } |
32 | |
33 | static inline |
34 | unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum) |
35 | { |
36 | int odd, count; |
37 | unsigned long result = (unsigned long)psum; |
38 | |
39 | if (len <= 0) |
40 | goto out; |
41 | odd = 1 & (unsigned long) buff; |
42 | if (odd) { |
43 | result = *buff << 8; |
44 | len--; |
45 | buff++; |
46 | } |
47 | count = len >> 1; /* nr of 16-bit words.. */ |
48 | if (count) { |
49 | if (2 & (unsigned long) buff) { |
50 | result += *(unsigned short *) buff; |
51 | count--; |
52 | len -= 2; |
53 | buff += 2; |
54 | } |
55 | count >>= 1; /* nr of 32-bit words.. */ |
56 | if (count) { |
57 | if (4 & (unsigned long) buff) { |
58 | result += *(unsigned int *) buff; |
59 | count--; |
60 | len -= 4; |
61 | buff += 4; |
62 | } |
63 | count >>= 1; /* nr of 64-bit words.. */ |
64 | if (count) { |
65 | unsigned long carry = 0; |
66 | do { |
67 | unsigned long w = *(unsigned long *) buff; |
68 | count--; |
69 | buff += 8; |
70 | result += carry; |
71 | result += w; |
72 | carry = (w > result); |
73 | } while (count); |
74 | result += carry; |
75 | result = (result & 0xffffffff) + (result >> 32); |
76 | } |
77 | if (len & 4) { |
78 | result += *(unsigned int *) buff; |
79 | buff += 4; |
80 | } |
81 | } |
82 | if (len & 2) { |
83 | result += *(unsigned short *) buff; |
84 | buff += 2; |
85 | } |
86 | } |
87 | if (len & 1) |
88 | result += *buff; |
89 | |
90 | result = from64to16(result); |
91 | |
92 | if (odd) |
93 | result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
94 | |
95 | out: |
96 | return result; |
97 | } |
98 | |
99 | /* |
100 | * XXX Fixme |
101 | * |
102 | * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS. |
103 | * But it's very tricky to get right even in C. |
104 | */ |
105 | extern unsigned long do_csum(const unsigned char *, long); |
106 | |
107 | __wsum |
108 | csum_partial_copy_from_user(const void __user *src, void *dst, |
109 | int len, __wsum psum, int *errp) |
110 | { |
111 | unsigned long result; |
112 | |
113 | /* XXX Fixme |
114 | * for now we separate the copy from checksum for obvious |
115 | * alignment difficulties. Look at the Alpha code and you'll be |
116 | * scared. |
117 | */ |
118 | |
119 | if (__copy_from_user(dst, src, len) != 0 && errp) |
120 | *errp = -EFAULT; |
121 | |
122 | result = do_csum(dst, len); |
123 | |
124 | /* add in old sum, and carry.. */ |
125 | result += (__force u32)psum; |
126 | /* 32+c bits -> 32 bits */ |
127 | result = (result & 0xffffffff) + (result >> 32); |
128 | return (__force __wsum)result; |
129 | } |
130 | |
131 | EXPORT_SYMBOL(csum_partial_copy_from_user); |
132 | |
133 | __wsum |
134 | csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) |
135 | { |
136 | return csum_partial_copy_from_user((__force const void __user *)src, |
137 | dst, len, sum, NULL); |
138 | } |
139 | |
140 | EXPORT_SYMBOL(csum_partial_copy_nocheck); |
141 |
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