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*/
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 * IP/TCP/UDP checksumming routines
7 *
8 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10 * Tom May, <ftom@netcom.com>
11 * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
12 * Lots of code moved from tcp.c and ip.c; see those files
13 * for more names.
14 *
15 * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
16 * Fixed some nasty bugs, causing some horrible crashes.
17 * A: At some points, the sum (%0) was used as
18 * length-counter instead of the length counter
19 * (%1). Thanks to Roman Hodek for pointing this out.
20 * B: GCC seems to mess up if one uses too many
21 * data-registers to hold input values and one tries to
22 * specify d0 and d1 as scratch registers. Letting gcc choose these
23 * registers itself solves the problem.
24 *
25 * This program is free software; you can redistribute it and/or
26 * modify it under the terms of the GNU General Public License
27 * as published by the Free Software Foundation; either version
28 * 2 of the License, or (at your option) any later version.
29 */
30
31 #include <net/checksum.h>
32
33 /*
34 * computes a partial checksum, e.g. for TCP/UDP fragments
35 */
36
37 unsigned int
38 csum_partial (const unsigned char *buff, int len, unsigned int sum)
/* ![[next]](../icons/right.png)
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*/
39 {
40 unsigned long tmp1, tmp2;
41 /*
42 * Experiments with ethernet and slip connections show that buff
43 * is aligned on either a 2-byte or 4-byte boundary.
44 */
45 __asm__("movel %2,%3\n\t"
46 "btst #1,%3\n\t" /* Check alignment */
47 "jeq 2f\n\t"
48 "subql #2,%1\n\t" /* buff%4==2: treat first word */
49 "jgt 1f\n\t"
50 "addql #2,%1\n\t" /* len was == 2, treat only rest */
51 "jra 4f\n"
52 "1:\t"
53 "addw %2@+,%0\n\t" /* add first word to sum */
54 "clrl %3\n\t"
55 "addxl %3,%0\n" /* add X bit */
56 "2:\t"
57 /* unrolled loop for the main part: do 8 longs at once */
58 "movel %1,%3\n\t" /* save len in tmp1 */
59 "lsrl #5,%1\n\t" /* len/32 */
60 "jeq 2f\n\t" /* not enough... */
61 "subql #1,%1\n"
62 "1:\t"
63 "movel %2@+,%4\n\t"
64 "addxl %4,%0\n\t"
65 "movel %2@+,%4\n\t"
66 "addxl %4,%0\n\t"
67 "movel %2@+,%4\n\t"
68 "addxl %4,%0\n\t"
69 "movel %2@+,%4\n\t"
70 "addxl %4,%0\n\t"
71 "movel %2@+,%4\n\t"
72 "addxl %4,%0\n\t"
73 "movel %2@+,%4\n\t"
74 "addxl %4,%0\n\t"
75 "movel %2@+,%4\n\t"
76 "addxl %4,%0\n\t"
77 "movel %2@+,%4\n\t"
78 "addxl %4,%0\n\t"
79 "dbra %1,1b\n\t"
80 "clrl %4\n\t"
81 "addxl %4,%0\n\t" /* add X bit */
82 "clrw %1\n\t"
83 "subql #1,%1\n\t"
84 "jcc 1b\n"
85 "2:\t"
86 "movel %3,%1\n\t" /* restore len from tmp1 */
87 "andw #0x1c,%3\n\t" /* number of rest longs */
88 "jeq 4f\n\t"
89 "lsrw #2,%3\n\t"
90 "subqw #1,%3\n"
91 "3:\t"
92 /* loop for rest longs */
93 "movel %2@+,%4\n\t"
94 "addxl %4,%0\n\t"
95 "dbra %3,3b\n\t"
96 "clrl %4\n\t"
97 "addxl %4,%0\n" /* add X bit */
98 "4:\t"
99 /* now check for rest bytes that do not fit into longs */
100 "andw #3,%1\n\t"
101 "jeq 7f\n\t"
102 "clrl %4\n\t" /* clear tmp2 for rest bytes */
103 "subqw #2,%1\n\t"
104 "jlt 5f\n\t"
105 "movew %2@+,%4\n\t" /* have rest >= 2: get word */
106 "swap %4\n\t" /* into bits 16..31 */
107 "tstw %1\n\t" /* another byte? */
108 "jeq 6f\n"
109 "5:\t"
110 "moveb %2@,%4\n\t" /* have odd rest: get byte */
111 "lslw #8,%4\n\t" /* into bits 8..15; 16..31 untouched */
112 "6:\t"
113 "addl %4,%0\n\t" /* now add rest long to sum */
114 "clrl %4\n\t"
115 "addxl %4,%0\n" /* add X bit */
116 "7:\t"
117 : "=d" (sum), "=d" (len), "=a" (buff),
118 "=&d" (tmp1), "=&d" (tmp2)
119 : "0" (sum), "1" (len), "2" (buff)
120 );
121 return(sum);
122 }
123
124
125
126 /*
127 * copy from fs while checksumming, otherwise like csum_partial
128 */
129
130 unsigned int
131 csum_partial_copy_fromuser(const char *src, char *dst, int len, int sum)
/* ![[previous]](../icons/left.png)
*/
132 {
133 unsigned long tmp1, tmp2;
134 __asm__("movel %2,%4\n\t"
135 "btst #1,%4\n\t" /* Check alignment */
136 "jeq 2f\n\t"
137 "subql #2,%1\n\t" /* buff%4==2: treat first word */
138 "jgt 1f\n\t"
139 "addql #2,%1\n\t" /* len was == 2, treat only rest */
140 "jra 4f\n"
141 "1:\t"
142 "movesw %2@+,%4\n\t" /* add first word to sum */
143 "addw %4,%0\n\t"
144 "movew %4,%3@+\n\t"
145 "clrl %4\n\t"
146 "addxl %4,%0\n" /* add X bit */
147 "2:\t"
148 /* unrolled loop for the main part: do 8 longs at once */
149 "movel %1,%4\n\t" /* save len in tmp1 */
150 "lsrl #5,%1\n\t" /* len/32 */
151 "jeq 2f\n\t" /* not enough... */
152 "subql #1,%1\n"
153 "1:\t"
154 "movesl %2@+,%5\n\t"
155 "addxl %5,%0\n\t"
156 "movel %5,%3@+\n\t"
157 "movesl %2@+,%5\n\t"
158 "addxl %5,%0\n\t"
159 "movel %5,%3@+\n\t"
160 "movesl %2@+,%5\n\t"
161 "addxl %5,%0\n\t"
162 "movel %5,%3@+\n\t"
163 "movesl %2@+,%5\n\t"
164 "addxl %5,%0\n\t"
165 "movel %5,%3@+\n\t"
166 "movesl %2@+,%5\n\t"
167 "addxl %5,%0\n\t"
168 "movel %5,%3@+\n\t"
169 "movesl %2@+,%5\n\t"
170 "addxl %5,%0\n\t"
171 "movel %5,%3@+\n\t"
172 "movesl %2@+,%5\n\t"
173 "addxl %5,%0\n\t"
174 "movel %5,%3@+\n\t"
175 "movesl %2@+,%5\n\t"
176 "addxl %5,%0\n\t"
177 "movel %5,%3@+\n\t"
178 "dbra %1,1b\n\t"
179 "clrl %5\n\t"
180 "addxl %5,%0\n\t" /* add X bit */
181 "clrw %1\n\t"
182 "subql #1,%1\n\t"
183 "jcc 1b\n"
184 "2:\t"
185 "movel %4,%1\n\t" /* restore len from tmp1 */
186 "andw #0x1c,%4\n\t" /* number of rest longs */
187 "jeq 4f\n\t"
188 "lsrw #2,%4\n\t"
189 "subqw #1,%4\n"
190 "3:\t"
191 /* loop for rest longs */
192 "movesl %2@+,%5\n\t"
193 "addxl %5,%0\n\t"
194 "movel %5,%3@+\n\t"
195 "dbra %4,3b\n\t"
196 "clrl %5\n\t"
197 "addxl %5,%0\n" /* add X bit */
198 "4:\t"
199 /* now check for rest bytes that do not fit into longs */
200 "andw #3,%1\n\t"
201 "jeq 7f\n\t"
202 "clrl %5\n\t" /* clear tmp2 for rest bytes */
203 "subqw #2,%1\n\t"
204 "jlt 5f\n\t"
205 "movesw %2@+,%5\n\t" /* have rest >= 2: get word */
206 "movew %5,%3@+\n\t"
207 "swap %5\n\t" /* into bits 16..31 */
208 "tstw %1\n\t" /* another byte? */
209 "jeq 6f\n"
210 "5:\t"
211 "movesb %2@,%5\n\t" /* have odd rest: get byte */
212 "moveb %5,%3@+\n\t"
213 "lslw #8,%5\n\t" /* into bits 8..15; 16..31 untouched */
214 "6:\t"
215 "addl %5,%0\n\t" /* now add rest long to sum */
216 "clrl %5\n\t"
217 "addxl %5,%0\n" /* add X bit */
218 "7:\t"
219 : "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
220 "=&d" (tmp1), "=&d" (tmp2)
221 : "0" (sum), "1" (len), "2" (src), "3" (dst)
222 );
223 return(sum);
224 }
225 /*
226 * copy from ds while checksumming, otherwise like csum_partial
227 */
228
229 unsigned int
230 csum_partial_copy(const char *src, char *dst, int len, int sum)
/* ![[last]](../icons/n_last.png)
*/
231 {
232 unsigned long tmp1, tmp2;
233 __asm__("movel %2,%4\n\t"
234 "btst #1,%4\n\t" /* Check alignment */
235 "jeq 2f\n\t"
236 "subql #2,%1\n\t" /* buff%4==2: treat first word */
237 "jgt 1f\n\t"
238 "addql #2,%1\n\t" /* len was == 2, treat only rest */
239 "jra 4f\n"
240 "1:\t"
241 "movew %2@+,%4\n\t" /* add first word to sum */
242 "addw %4,%0\n\t"
243 "movew %4,%3@+\n\t"
244 "clrl %4\n\t"
245 "addxl %4,%0\n" /* add X bit */
246 "2:\t"
247 /* unrolled loop for the main part: do 8 longs at once */
248 "movel %1,%4\n\t" /* save len in tmp1 */
249 "lsrl #5,%1\n\t" /* len/32 */
250 "jeq 2f\n\t" /* not enough... */
251 "subql #1,%1\n"
252 "1:\t"
253 "movel %2@+,%5\n\t"
254 "addxl %5,%0\n\t"
255 "movel %5,%3@+\n\t"
256 "movel %2@+,%5\n\t"
257 "addxl %5,%0\n\t"
258 "movel %5,%3@+\n\t"
259 "movel %2@+,%5\n\t"
260 "addxl %5,%0\n\t"
261 "movel %5,%3@+\n\t"
262 "movel %2@+,%5\n\t"
263 "addxl %5,%0\n\t"
264 "movel %5,%3@+\n\t"
265 "movel %2@+,%5\n\t"
266 "addxl %5,%0\n\t"
267 "movel %5,%3@+\n\t"
268 "movel %2@+,%5\n\t"
269 "addxl %5,%0\n\t"
270 "movel %5,%3@+\n\t"
271 "movel %2@+,%5\n\t"
272 "addxl %5,%0\n\t"
273 "movel %5,%3@+\n\t"
274 "movel %2@+,%5\n\t"
275 "addxl %5,%0\n\t"
276 "movel %5,%3@+\n\t"
277 "dbra %1,1b\n\t"
278 "clrl %5\n\t"
279 "addxl %5,%0\n\t" /* add X bit */
280 "clrw %1\n\t"
281 "subql #1,%1\n\t"
282 "jcc 1b\n"
283 "2:\t"
284 "movel %4,%1\n\t" /* restore len from tmp1 */
285 "andw #0x1c,%4\n\t" /* number of rest longs */
286 "jeq 4f\n\t"
287 "lsrw #2,%4\n\t"
288 "subqw #1,%4\n"
289 "3:\t"
290 /* loop for rest longs */
291 "movel %2@+,%5\n\t"
292 "addxl %5,%0\n\t"
293 "movel %5,%3@+\n\t"
294 "dbra %4,3b\n\t"
295 "clrl %5\n\t"
296 "addxl %5,%0\n" /* add X bit */
297 "4:\t"
298 /* now check for rest bytes that do not fit into longs */
299 "andw #3,%1\n\t"
300 "jeq 7f\n\t"
301 "clrl %5\n\t" /* clear tmp2 for rest bytes */
302 "subqw #2,%1\n\t"
303 "jlt 5f\n\t"
304 "movew %2@+,%5\n\t" /* have rest >= 2: get word */
305 "movew %5,%3@+\n\t"
306 "swap %5\n\t" /* into bits 16..31 */
307 "tstw %1\n\t" /* another byte? */
308 "jeq 6f\n"
309 "5:\t"
310 "moveb %2@,%5\n\t" /* have odd rest: get byte */
311 "moveb %5,%3@+\n\t"
312 "lslw #8,%5\n" /* into bits 8..15; 16..31 untouched */
313 "6:\t"
314 "addl %5,%0\n\t" /* now add rest long to sum */
315 "clrl %5\n\t"
316 "addxl %5,%0\n" /* add X bit */
317 "7:\t"
318 : "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
319 "=&d" (tmp1), "=&d" (tmp2)
320 : "0" (sum), "1" (len), "2" (src), "3" (dst)
321 );
322 return(sum);
323 }
![[bottom]](../icons/n_bottom.png){kind=icon}
*/