File: /usr/src/linux/include/asm-arm/checksum.h
1 /*
2 * linux/include/asm-arm/checksum.h
3 *
4 * IP checksum routines
5 *
6 * Copyright (C) Original authors of ../asm-i386/checksum.h
7 * Copyright (C) 1996-1999 Russell King
8 */
9 #ifndef __ASM_ARM_CHECKSUM_H
10 #define __ASM_ARM_CHECKSUM_H
11
12 /*
13 * computes the checksum of a memory block at buff, length len,
14 * and adds in "sum" (32-bit)
15 *
16 * returns a 32-bit number suitable for feeding into itself
17 * or csum_tcpudp_magic
18 *
19 * this function must be called with even lengths, except
20 * for the last fragment, which may be odd
21 *
22 * it's best to have buff aligned on a 32-bit boundary
23 */
24 unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
25
26 /*
27 * the same as csum_partial, but copies from src while it
28 * checksums, and handles user-space pointer exceptions correctly, when needed.
29 *
30 * here even more important to align src and dst on a 32-bit (or even
31 * better 64-bit) boundary
32 */
33
34 unsigned int
35 csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum);
36
37 unsigned int
38 csum_partial_copy_from_user(const char *src, char *dst, int len, int sum, int *err_ptr);
39
40 /*
41 * These are the old (and unsafe) way of doing checksums, a warning message will be
42 * printed if they are used and an exception occurs.
43 *
44 * these functions should go away after some time.
45 */
46 #define csum_partial_copy(src,dst,len,sum) csum_partial_copy_nocheck(src,dst,len,sum)
47
48 /*
49 * This is a version of ip_compute_csum() optimized for IP headers,
50 * which always checksum on 4 octet boundaries.
51 */
52 static inline unsigned short
53 ip_fast_csum(unsigned char * iph, unsigned int ihl)
54 {
55 unsigned int sum, tmp1;
56
57 __asm__ __volatile__(
58 "ldr %0, [%1], #4 @ ip_fast_csum
59 ldr %3, [%1], #4
60 sub %2, %2, #5
61 adds %0, %0, %3
62 ldr %3, [%1], #4
63 adcs %0, %0, %3
64 ldr %3, [%1], #4
65 adcs %0, %0, %3
66 1: ldr %3, [%1], #4
67 adcs %0, %0, %3
68 tst %2, #15
69 subne %2, %2, #1
70 bne 1b
71 adc %0, %0, #0
72 adds %0, %0, %0, lsl #16
73 addcs %0, %0, #0x10000
74 mvn %0, %0
75 mov %0, %0, lsr #16
76 "
77 : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
78 : "1" (iph), "2" (ihl)
79 : "cc");
80 return sum;
81 }
82
83 /*
84 * Fold a partial checksum without adding pseudo headers
85 */
86 static inline unsigned int
87 csum_fold(unsigned int sum)
88 {
89 __asm__(
90 "adds %0, %1, %1, lsl #16 @ csum_fold
91 addcs %0, %0, #0x10000"
92 : "=r" (sum)
93 : "r" (sum)
94 : "cc");
95 return (~sum) >> 16;
96 }
97
98 static inline unsigned int
99 csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
100 unsigned int proto, unsigned int sum)
101 {
102 __asm__(
103 "adds %0, %1, %2 @ csum_tcpudp_nofold
104 adcs %0, %0, %3
105 adcs %0, %0, %4
106 adcs %0, %0, %5
107 adc %0, %0, #0"
108 : "=&r"(sum)
109 : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len) << 16), "Ir" (proto << 8)
110 : "cc");
111 return sum;
112 }
113 /*
114 * computes the checksum of the TCP/UDP pseudo-header
115 * returns a 16-bit checksum, already complemented
116 */
117 static inline unsigned short int
118 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
119 unsigned int proto, unsigned int sum)
120 {
121 __asm__(
122 "adds %0, %1, %2 @ csum_tcpudp_magic
123 adcs %0, %0, %3
124 adcs %0, %0, %4
125 adcs %0, %0, %5
126 adc %0, %0, #0
127 adds %0, %0, %0, lsl #16
128 addcs %0, %0, #0x10000
129 mvn %0, %0"
130 : "=&r"(sum)
131 : "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (proto << 8)
132 : "cc");
133 return sum >> 16;
134 }
135
136
137 /*
138 * this routine is used for miscellaneous IP-like checksums, mainly
139 * in icmp.c
140 */
141 static inline unsigned short
142 ip_compute_csum(unsigned char * buff, int len)
143 {
144 return csum_fold(csum_partial(buff, len, 0));
145 }
146
147 #define _HAVE_ARCH_IPV6_CSUM
148 extern unsigned long
149 __csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
150 __u32 proto, unsigned int sum);
151
152 static inline unsigned short int
153 csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
154 unsigned short proto, unsigned int sum)
155 {
156 return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
157 htonl(proto), sum));
158 }
159 #endif
160