atomic: use <linux/atomic.h>
[linux-2.6.git] / arch / parisc / lib / checksum.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              MIPS specific IP/TCP/UDP checksumming routines
7  *
8  * Authors:     Ralf Baechle, <ralf@waldorf-gmbh.de>
9  *              Lots of code moved from tcp.c and ip.c; see those files
10  *              for more names.
11  *
12  *              This program is free software; you can redistribute it and/or
13  *              modify it under the terms of the GNU General Public License
14  *              as published by the Free Software Foundation; either version
15  *              2 of the License, or (at your option) any later version.
16  */
17 #include <linux/module.h>
18 #include <linux/types.h>
19
20 #include <net/checksum.h>
21 #include <asm/byteorder.h>
22 #include <asm/string.h>
23 #include <asm/uaccess.h>
24
25 #define addc(_t,_r)                     \
26         __asm__ __volatile__ (          \
27 "       add             %0, %1, %0\n"   \
28 "       addc            %0, %%r0, %0\n" \
29         : "=r"(_t)                      \
30         : "r"(_r), "0"(_t));
31
32 static inline unsigned short from32to16(unsigned int x)
33 {
34         /* 32 bits --> 16 bits + carry */
35         x = (x & 0xffff) + (x >> 16);
36         /* 16 bits + carry --> 16 bits including carry */
37         x = (x & 0xffff) + (x >> 16);
38         return (unsigned short)x;
39 }
40
41 static inline unsigned int do_csum(const unsigned char * buff, int len)
42 {
43         int odd, count;
44         unsigned int result = 0;
45
46         if (len <= 0)
47                 goto out;
48         odd = 1 & (unsigned long) buff;
49         if (odd) {
50                 result = be16_to_cpu(*buff);
51                 len--;
52                 buff++;
53         }
54         count = len >> 1;               /* nr of 16-bit words.. */
55         if (count) {
56                 if (2 & (unsigned long) buff) {
57                         result += *(unsigned short *) buff;
58                         count--;
59                         len -= 2;
60                         buff += 2;
61                 }
62                 count >>= 1;            /* nr of 32-bit words.. */
63                 if (count) {
64                         while (count >= 4) {
65                                 unsigned int r1, r2, r3, r4;
66                                 r1 = *(unsigned int *)(buff + 0);
67                                 r2 = *(unsigned int *)(buff + 4);
68                                 r3 = *(unsigned int *)(buff + 8);
69                                 r4 = *(unsigned int *)(buff + 12);
70                                 addc(result, r1);
71                                 addc(result, r2);
72                                 addc(result, r3);
73                                 addc(result, r4);
74                                 count -= 4;
75                                 buff += 16;
76                         }
77                         while (count) {
78                                 unsigned int w = *(unsigned int *) buff;
79                                 count--;
80                                 buff += 4;
81                                 addc(result, w);
82                         }
83                         result = (result & 0xffff) + (result >> 16);
84                 }
85                 if (len & 2) {
86                         result += *(unsigned short *) buff;
87                         buff += 2;
88                 }
89         }
90         if (len & 1)
91                 result += le16_to_cpu(*buff);
92         result = from32to16(result);
93         if (odd)
94                 result = swab16(result);
95 out:
96         return result;
97 }
98
99 /*
100  * computes a partial checksum, e.g. for TCP/UDP fragments
101  */
102 /*
103  * why bother folding?
104  */
105 __wsum csum_partial(const void *buff, int len, __wsum sum)
106 {
107         unsigned int result = do_csum(buff, len);
108         addc(result, sum);
109         return (__force __wsum)from32to16(result);
110 }
111
112 EXPORT_SYMBOL(csum_partial);
113
114 /*
115  * copy while checksumming, otherwise like csum_partial
116  */
117 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
118                                        int len, __wsum sum)
119 {
120         /*
121          * It's 2:30 am and I don't feel like doing it real ...
122          * This is lots slower than the real thing (tm)
123          */
124         sum = csum_partial(src, len, sum);
125         memcpy(dst, src, len);
126
127         return sum;
128 }
129 EXPORT_SYMBOL(csum_partial_copy_nocheck);
130
131 /*
132  * Copy from userspace and compute checksum.  If we catch an exception
133  * then zero the rest of the buffer.
134  */
135 __wsum csum_partial_copy_from_user(const void __user *src,
136                                         void *dst, int len,
137                                         __wsum sum, int *err_ptr)
138 {
139         int missing;
140
141         missing = copy_from_user(dst, src, len);
142         if (missing) {
143                 memset(dst + len - missing, 0, missing);
144                 *err_ptr = -EFAULT;
145         }
146                 
147         return csum_partial(dst, len, sum);
148 }
149 EXPORT_SYMBOL(csum_partial_copy_from_user);