1/*
2 * arch/sh64/lib/c-checksum.c
3 *
4 * This file contains network checksum routines that are better done
5 * in an architecture-specific manner due to speed..
6 */
7
8#undef DEBUG
9
10#include <linux/string.h>
11#include <linux/errno.h>
12#include <linux/kernel.h>
13#include <asm/byteorder.h>
14#include <asm/uaccess.h>
15
16static inline unsigned short from64to16(unsigned long long x)
17{
18	/* add up 32-bit words for 33 bits */
19	x = (x & 0xffffffff) + (x >> 32);
20	/* add up 16-bit and 17-bit words for 17+c bits */
21	x = (x & 0xffff) + (x >> 16);
22	/* add up 16-bit and 2-bit for 16+c bit */
23	x = (x & 0xffff) + (x >> 16);
24	/* add up carry.. */
25	x = (x & 0xffff) + (x >> 16);
26	return x;
27}
28
29static inline unsigned short foldto16(unsigned long x)
30{
31	/* add up 16-bit for 17 bits */
32	x = (x & 0xffff) + (x >> 16);
33	/* add up carry.. */
34	x = (x & 0xffff) + (x >> 16);
35	return x;
36}
37
38static inline unsigned short myfoldto16(unsigned long long x)
39{
40	/* Fold down to 32-bits so we don't loose in the typedef-less
41	   network stack.  */
42	/* 64 to 33 */
43	x = (x & 0xffffffff) + (x >> 32);
44	/* 33 to 32 */
45	x = (x & 0xffffffff) + (x >> 32);
46
47	/* add up 16-bit for 17 bits */
48	x = (x & 0xffff) + (x >> 16);
49	/* add up carry.. */
50	x = (x & 0xffff) + (x >> 16);
51	return x;
52}
53
54#define odd(x) ((x)&1)
55#define U16(x) ntohs(x)
56
57static unsigned long do_csum(const unsigned char *buff, int len)
58{
59	int odd, count;
60	unsigned long result = 0;
61
62	pr_debug("do_csum buff %p, len %d (0x%x)\n", buff, len, len);
63#ifdef DEBUG
64	for (i = 0; i < len; i++) {
65		if ((i % 26) == 0)
66			printk("\n");
67		printk("%02X ", buff[i]);
68	}
69#endif
70
71	if (len <= 0)
72		goto out;
73
74	odd = 1 & (unsigned long) buff;
75	if (odd) {
76		result = *buff << 8;
77		len--;
78		buff++;
79	}
80	count = len >> 1;	/* nr of 16-bit words.. */
81	if (count) {
82		if (2 & (unsigned long) buff) {
83			result += *(unsigned short *) buff;
84			count--;
85			len -= 2;
86			buff += 2;
87		}
88		count >>= 1;	/* nr of 32-bit words.. */
89		if (count) {
90			unsigned long carry = 0;
91			do {
92				unsigned long w = *(unsigned long *) buff;
93				buff += 4;
94				count--;
95				result += carry;
96				result += w;
97				carry = (w > result);
98			} while (count);
99			result += carry;
100			result = (result & 0xffff) + (result >> 16);
101		}
102		if (len & 2) {
103			result += *(unsigned short *) buff;
104			buff += 2;
105		}
106	}
107	if (len & 1)
108		result += *buff;
109	result = foldto16(result);
110	if (odd)
111		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
112
113	pr_debug("\nCHECKSUM is 0x%x\n", result);
114
115      out:
116	return result;
117}
118
119/* computes the checksum of a memory block at buff, length len,
120   and adds in "sum" (32-bit)  */
121__wsum csum_partial(const void *buff, int len, __wsum sum)
122{
123	unsigned long long result = do_csum(buff, len);
124
125	/* add in old sum, and carry.. */
126	result += (__force u32)sum;
127	/* 32+c bits -> 32 bits */
128	result = (result & 0xffffffff) + (result >> 32);
129
130	pr_debug("csum_partial, buff %p len %d sum 0x%x result=0x%016Lx\n",
131		buff, len, sum, result);
132
133	return (__force __wsum)result;
134}
135
136/* Copy while checksumming, otherwise like csum_partial.  */
137__wsum
138csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
139{
140	sum = csum_partial(src, len, sum);
141	memcpy(dst, src, len);
142
143	return sum;
144}
145
146/* Copy from userspace and compute checksum.  If we catch an exception
147   then zero the rest of the buffer.  */
148__wsum
149csum_partial_copy_from_user(const void __user *src, void *dst, int len,
150			    __wsum sum, int *err_ptr)
151{
152	int missing;
153
154	pr_debug
155	    ("csum_partial_copy_from_user src %p, dest %p, len %d, sum %08x, err_ptr %p\n",
156	     src, dst, len, sum, err_ptr);
157	missing = copy_from_user(dst, src, len);
158	pr_debug("  access_ok %d\n", __access_ok((unsigned long) src, len));
159	pr_debug("  missing %d\n", missing);
160	if (missing) {
161		memset(dst + len - missing, 0, missing);
162		*err_ptr = -EFAULT;
163	}
164
165	return csum_partial(dst, len, sum);
166}
167
168/* Copy to userspace and compute checksum.  */
169__wsum
170csum_partial_copy_to_user(const unsigned char *src, unsigned char *dst, int len,
171			  __wsum sum, int *err_ptr)
172{
173	sum = csum_partial(src, len, sum);
174
175	if (copy_to_user(dst, src, len))
176		*err_ptr = -EFAULT;
177
178	return sum;
179}
180
181/*
182 *	This is a version of ip_compute_csum() optimized for IP headers,
183 *	which always checksum on 4 octet boundaries.
184 */
185__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
186{
187	pr_debug("ip_fast_csum %p,%d\n", iph, ihl);
188
189	return (__force __sum16)~do_csum(iph, ihl * 4);
190}
191
192__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
193				unsigned short len,
194				unsigned short proto, __wsum sum)
195{
196	unsigned long long result;
197
198	pr_debug("ntohs(0x%x)=0x%x\n", 0xdead, ntohs(0xdead));
199	pr_debug("htons(0x%x)=0x%x\n", 0xdead, htons(0xdead));
200
201	result = (__force u64) saddr + (__force u64) daddr +
202		 (__force u64) sum + ((len + proto) << 8);
203
204	/* Fold down to 32-bits so we don't loose in the typedef-less
205	   network stack.  */
206	/* 64 to 33 */
207	result = (result & 0xffffffff) + (result >> 32);
208	/* 33 to 32 */
209	result = (result & 0xffffffff) + (result >> 32);
210
211	pr_debug("%s saddr %x daddr %x len %x proto %x sum %x result %08Lx\n",
212		__FUNCTION__, saddr, daddr, len, proto, sum, result);
213
214	return (__wsum)result;
215}
216