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 */
24unsigned 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
34unsigned int
35csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum);
36
37unsigned int
38csum_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 */
52static inline unsigned short
53ip_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		\n\
59	ldr	%3, [%1], #4					\n\
60	sub	%2, %2, #5					\n\
61	adds	%0, %0, %3					\n\
62	ldr	%3, [%1], #4					\n\
63	adcs	%0, %0, %3					\n\
64	ldr	%3, [%1], #4					\n\
651:	adcs	%0, %0, %3					\n\
66	ldr	%3, [%1], #4					\n\
67	tst	%2, #15			@ do this carefully	\n\
68	subne	%2, %2, #1		@ without destroying	\n\
69	bne	1b			@ the carry flag	\n\
70	adcs	%0, %0, %3					\n\
71	adc	%0, %0, #0					\n\
72	adds	%0, %0, %0, lsl #16				\n\
73	addcs	%0, %0, #0x10000				\n\
74	mvn	%0, %0						\n\
75	mov	%0, %0, lsr #16"
76	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
77	: "1" (iph), "2" (ihl)
78	: "cc");
79	return sum;
80}
81
82/*
83 * 	Fold a partial checksum without adding pseudo headers
84 */
85static inline unsigned int
86csum_fold(unsigned int sum)
87{
88	__asm__(
89	"adds	%0, %1, %1, lsl #16	@ csum_fold		\n\
90	addcs	%0, %0, #0x10000"
91	: "=r" (sum)
92	: "r" (sum)
93	: "cc");
94	return (~sum) >> 16;
95}
96
97static inline unsigned int
98csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
99		   unsigned int proto, unsigned int sum)
100{
101	__asm__(
102	"adds	%0, %1, %2		@ csum_tcpudp_nofold	\n\
103	adcs	%0, %0, %3					\n\
104	adcs	%0, %0, %4					\n\
105	adcs	%0, %0, %5					\n\
106	adc	%0, %0, #0"
107	: "=&r"(sum)
108	: "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len) << 16), "Ir" (proto << 8)
109	: "cc");
110	return sum;
111}
112/*
113 * computes the checksum of the TCP/UDP pseudo-header
114 * returns a 16-bit checksum, already complemented
115 */
116static inline unsigned short int
117csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
118		  unsigned int proto, unsigned int sum)
119{
120	__asm__(
121	"adds	%0, %1, %2		@ csum_tcpudp_magic	\n\
122	adcs	%0, %0, %3					\n\
123	adcs	%0, %0, %4					\n\
124	adcs	%0, %0, %5					\n\
125	adc	%0, %0, #0					\n\
126	adds	%0, %0, %0, lsl #16				\n\
127	addcs	%0, %0, #0x10000				\n\
128	mvn	%0, %0"
129	: "=&r"(sum)
130	: "r" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)), "Ir" (proto << 8)
131	: "cc");
132	return sum >> 16;
133}
134
135
136/*
137 * this routine is used for miscellaneous IP-like checksums, mainly
138 * in icmp.c
139 */
140static inline unsigned short
141ip_compute_csum(unsigned char * buff, int len)
142{
143	return csum_fold(csum_partial(buff, len, 0));
144}
145
146#define _HAVE_ARCH_IPV6_CSUM
147extern unsigned long
148__csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
149		__u32 proto, unsigned int sum);
150
151static inline unsigned short int
152csum_ipv6_magic(struct in6_addr *saddr, struct in6_addr *daddr, __u32 len,
153		unsigned short proto, unsigned int sum)
154{
155	return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
156					   htonl(proto), sum));
157}
158#endif
159