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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
4 | * operating system. INET is implemented using the BSD Socket | |
5 | * interface as the means of communication with the user level. | |
6 | * | |
7 | * MIPS specific IP/TCP/UDP checksumming routines | |
8 | * | |
9 | * Authors: Ralf Baechle, <ralf@waldorf-gmbh.de> | |
10 | * Lots of code moved from tcp.c and ip.c; see those files | |
11 | * for more names. | |
1da177e4 LT |
12 | */ |
13 | #include <linux/module.h> | |
14 | #include <linux/types.h> | |
15 | ||
16 | #include <net/checksum.h> | |
17 | #include <asm/byteorder.h> | |
18 | #include <asm/string.h> | |
7c0f6ba6 | 19 | #include <linux/uaccess.h> |
1da177e4 LT |
20 | |
21 | #define addc(_t,_r) \ | |
22 | __asm__ __volatile__ ( \ | |
23 | " add %0, %1, %0\n" \ | |
24 | " addc %0, %%r0, %0\n" \ | |
25 | : "=r"(_t) \ | |
26 | : "r"(_r), "0"(_t)); | |
27 | ||
28 | static inline unsigned short from32to16(unsigned int x) | |
29 | { | |
30 | /* 32 bits --> 16 bits + carry */ | |
31 | x = (x & 0xffff) + (x >> 16); | |
32 | /* 16 bits + carry --> 16 bits including carry */ | |
33 | x = (x & 0xffff) + (x >> 16); | |
34 | return (unsigned short)x; | |
35 | } | |
36 | ||
37 | static inline unsigned int do_csum(const unsigned char * buff, int len) | |
38 | { | |
39 | int odd, count; | |
40 | unsigned int result = 0; | |
41 | ||
42 | if (len <= 0) | |
43 | goto out; | |
44 | odd = 1 & (unsigned long) buff; | |
45 | if (odd) { | |
46 | result = be16_to_cpu(*buff); | |
47 | len--; | |
48 | buff++; | |
49 | } | |
50 | count = len >> 1; /* nr of 16-bit words.. */ | |
51 | if (count) { | |
52 | if (2 & (unsigned long) buff) { | |
53 | result += *(unsigned short *) buff; | |
54 | count--; | |
55 | len -= 2; | |
56 | buff += 2; | |
57 | } | |
58 | count >>= 1; /* nr of 32-bit words.. */ | |
59 | if (count) { | |
60 | while (count >= 4) { | |
61 | unsigned int r1, r2, r3, r4; | |
62 | r1 = *(unsigned int *)(buff + 0); | |
63 | r2 = *(unsigned int *)(buff + 4); | |
64 | r3 = *(unsigned int *)(buff + 8); | |
65 | r4 = *(unsigned int *)(buff + 12); | |
66 | addc(result, r1); | |
67 | addc(result, r2); | |
68 | addc(result, r3); | |
69 | addc(result, r4); | |
70 | count -= 4; | |
71 | buff += 16; | |
72 | } | |
73 | while (count) { | |
74 | unsigned int w = *(unsigned int *) buff; | |
75 | count--; | |
76 | buff += 4; | |
77 | addc(result, w); | |
78 | } | |
79 | result = (result & 0xffff) + (result >> 16); | |
80 | } | |
81 | if (len & 2) { | |
82 | result += *(unsigned short *) buff; | |
83 | buff += 2; | |
84 | } | |
85 | } | |
86 | if (len & 1) | |
87 | result += le16_to_cpu(*buff); | |
88 | result = from32to16(result); | |
89 | if (odd) | |
90 | result = swab16(result); | |
91 | out: | |
92 | return result; | |
93 | } | |
94 | ||
95 | /* | |
96 | * computes a partial checksum, e.g. for TCP/UDP fragments | |
97 | */ | |
7814e4b6 AV |
98 | /* |
99 | * why bother folding? | |
100 | */ | |
101 | __wsum csum_partial(const void *buff, int len, __wsum sum) | |
1da177e4 LT |
102 | { |
103 | unsigned int result = do_csum(buff, len); | |
104 | addc(result, sum); | |
7814e4b6 | 105 | return (__force __wsum)from32to16(result); |
1da177e4 LT |
106 | } |
107 | ||
108 | EXPORT_SYMBOL(csum_partial); | |
109 | ||
110 | /* | |
111 | * copy while checksumming, otherwise like csum_partial | |
112 | */ | |
7814e4b6 AV |
113 | __wsum csum_partial_copy_nocheck(const void *src, void *dst, |
114 | int len, __wsum sum) | |
1da177e4 LT |
115 | { |
116 | /* | |
117 | * It's 2:30 am and I don't feel like doing it real ... | |
118 | * This is lots slower than the real thing (tm) | |
119 | */ | |
120 | sum = csum_partial(src, len, sum); | |
121 | memcpy(dst, src, len); | |
122 | ||
123 | return sum; | |
124 | } | |
125 | EXPORT_SYMBOL(csum_partial_copy_nocheck); |