aboutsummaryrefslogtreecommitdiffstats
path: root/arch/sh/lib64/c-checksum.c
blob: 053137abd8a00843ec374c27cc8b44a0d271c65f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
/*
 * arch/sh64/lib/c-checksum.c
 *
 * This file contains network checksum routines that are better done
 * in an architecture-specific manner due to speed..
 */

#undef DEBUG

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/byteorder.h>
#include <asm/uaccess.h>

static inline unsigned short from64to16(unsigned long long x)
{
	/* add up 32-bit words for 33 bits */
	x = (x & 0xffffffff) + (x >> 32);
	/* add up 16-bit and 17-bit words for 17+c bits */
	x = (x & 0xffff) + (x >> 16);
	/* add up 16-bit and 2-bit for 16+c bit */
	x = (x & 0xffff) + (x >> 16);
	/* add up carry.. */
	x = (x & 0xffff) + (x >> 16);
	return x;
}

static inline unsigned short foldto16(unsigned long x)
{
	/* add up 16-bit for 17 bits */
	x = (x & 0xffff) + (x >> 16);
	/* add up carry.. */
	x = (x & 0xffff) + (x >> 16);
	return x;
}

static inline unsigned short myfoldto16(unsigned long long x)
{
	/* Fold down to 32-bits so we don't loose in the typedef-less
	   network stack.  */
	/* 64 to 33 */
	x = (x & 0xffffffff) + (x >> 32);
	/* 33 to 32 */
	x = (x & 0xffffffff) + (x >> 32);

	/* add up 16-bit for 17 bits */
	x = (x & 0xffff) + (x >> 16);
	/* add up carry.. */
	x = (x & 0xffff) + (x >> 16);
	return x;
}

#define odd(x) ((x)&1)
#define U16(x) ntohs(x)

static unsigned long do_csum(const unsigned char *buff, int len)
{
	int odd, count;
	unsigned long result = 0;

	pr_debug("do_csum buff %p, len %d (0x%x)\n", buff, len, len);
#ifdef DEBUG
	for (i = 0; i < len; i++) {
		if ((i % 26) == 0)
			printk("\n");
		printk("%02X ", buff[i]);
	}
#endif

	if (len <= 0)
		goto out;

	odd = 1 & (unsigned long) buff;
	if (odd) {
		result = *buff << 8;
		len--;
		buff++;
	}
	count = len >> 1;	/* nr of 16-bit words.. */
	if (count) {
		if (2 & (unsigned long) buff) {
			result += *(unsigned short *) buff;
			count--;
			len -= 2;
			buff += 2;
		}
		count >>= 1;	/* nr of 32-bit words.. */
		if (count) {
			unsigned long carry = 0;
			do {
				unsigned long w = *(unsigned long *) buff;
				buff += 4;
				count--;
				result += carry;
				result += w;
				carry = (w > result);
			} while (count);
			result += carry;
			result = (result & 0xffff) + (result >> 16);
		}
		if (len & 2) {
			result += *(unsigned short *) buff;
			buff += 2;
		}
	}
	if (len & 1)
		result += *buff;
	result = foldto16(result);
	if (odd)
		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);

	pr_debug("\nCHECKSUM is 0x%lx\n", result);

      out:
	return result;
}

/* computes the checksum of a memory block at buff, length len,
   and adds in "sum" (32-bit)  */
__wsum csum_partial(const void *buff, int len, __wsum sum)
{
	unsigned long long result = do_csum(buff, len);

	/* add in old sum, and carry.. */
	result += (__force u32)sum;
	/* 32+c bits -> 32 bits */
	result = (result & 0xffffffff) + (result >> 32);

	pr_debug("csum_partial, buff %p len %d sum 0x%x result=0x%016Lx\n",
		buff, len, sum, result);

	return (__force __wsum)result;
}

/* Copy while checksumming, otherwise like csum_partial.  */
__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
	sum = csum_partial(src, len, sum);
	memcpy(dst, src, len);

	return sum;
}

/* Copy from userspace and compute checksum.  If we catch an exception
   then zero the rest of the buffer.  */
__wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len,
			    __wsum sum, int *err_ptr)
{
	int missing;

	pr_debug
	    ("csum_partial_copy_from_user src %p, dest %p, len %d, sum %08x, err_ptr %p\n",
	     src, dst, len, sum, err_ptr);
	missing = copy_from_user(dst, src, len);
	pr_debug("  access_ok %d\n", __access_ok((unsigned long) src, len));
	pr_debug("  missing %d\n", missing);
	if (missing) {
		memset(dst + len - missing, 0, missing);
		*err_ptr = -EFAULT;
	}

	return csum_partial(dst, len, sum);
}

/* Copy to userspace and compute checksum.  */
__wsum
csum_partial_copy_to_user(const unsigned char *src, unsigned char *dst, int len,
			  __wsum sum, int *err_ptr)
{
	sum = csum_partial(src, len, sum);

	if (copy_to_user(dst, src, len))
		*err_ptr = -EFAULT;

	return sum;
}

/*
 *	This is a version of ip_compute_csum() optimized for IP headers,
 *	which always checksum on 4 octet boundaries.
 */
__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
	pr_debug("ip_fast_csum %p,%d\n", iph, ihl);

	return (__force __sum16)~do_csum(iph, ihl * 4);
}

__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
				unsigned short len,
				unsigned short proto, __wsum sum)
{
	unsigned long long result;

	pr_debug("ntohs(0x%x)=0x%x\n", 0xdead, ntohs(0xdead));
	pr_debug("htons(0x%x)=0x%x\n", 0xdead, htons(0xdead));

	result = (__force u64) saddr + (__force u64) daddr +
		 (__force u64) sum + ((len + proto) << 8);

	/* Fold down to 32-bits so we don't loose in the typedef-less
	   network stack.  */
	/* 64 to 33 */
	result = (result & 0xffffffff) + (result >> 32);
	/* 33 to 32 */
	result = (result & 0xffffffff) + (result >> 32);

	pr_debug("%s saddr %x daddr %x len %x proto %x sum %x result %08Lx\n",
		__FUNCTION__, saddr, daddr, len, proto, sum, result);

	return (__wsum)result;
}
EXPORT_SYMBOL(csum_tcpudp_nofold);