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-rw-r--r--drivers/isdn/hisax/st5481_hdlc.c580
1 files changed, 580 insertions, 0 deletions
diff --git a/drivers/isdn/hisax/st5481_hdlc.c b/drivers/isdn/hisax/st5481_hdlc.c
new file mode 100644
index 000000000000..680f42e9a993
--- /dev/null
+++ b/drivers/isdn/hisax/st5481_hdlc.c
@@ -0,0 +1,580 @@
1/*
2 * Driver for ST5481 USB ISDN modem
3 *
4 * Author Frode Isaksen
5 * Copyright 2001 by Frode Isaksen <fisaksen@bewan.com>
6 * 2001 by Kai Germaschewski <kai.germaschewski@gmx.de>
7 *
8 * This software may be used and distributed according to the terms
9 * of the GNU General Public License, incorporated herein by reference.
10 *
11 */
12
13#include <linux/crc-ccitt.h>
14#include "st5481_hdlc.h"
15
16
17enum {
18 HDLC_FAST_IDLE,HDLC_GET_FLAG_B0,HDLC_GETFLAG_B1A6,HDLC_GETFLAG_B7,
19 HDLC_GET_DATA,HDLC_FAST_FLAG
20};
21
22enum {
23 HDLC_SEND_DATA,HDLC_SEND_CRC1,HDLC_SEND_FAST_FLAG,
24 HDLC_SEND_FIRST_FLAG,HDLC_SEND_CRC2,HDLC_SEND_CLOSING_FLAG,
25 HDLC_SEND_IDLE1,HDLC_SEND_FAST_IDLE,HDLC_SENDFLAG_B0,
26 HDLC_SENDFLAG_B1A6,HDLC_SENDFLAG_B7,STOPPED
27};
28
29void
30hdlc_rcv_init(struct hdlc_vars *hdlc, int do_adapt56)
31{
32 hdlc->bit_shift = 0;
33 hdlc->hdlc_bits1 = 0;
34 hdlc->data_bits = 0;
35 hdlc->ffbit_shift = 0;
36 hdlc->data_received = 0;
37 hdlc->state = HDLC_GET_DATA;
38 hdlc->do_adapt56 = do_adapt56;
39 hdlc->dchannel = 0;
40 hdlc->crc = 0;
41 hdlc->cbin = 0;
42 hdlc->shift_reg = 0;
43 hdlc->ffvalue = 0;
44 hdlc->dstpos = 0;
45}
46
47void
48hdlc_out_init(struct hdlc_vars *hdlc, int is_d_channel, int do_adapt56)
49{
50 hdlc->bit_shift = 0;
51 hdlc->hdlc_bits1 = 0;
52 hdlc->data_bits = 0;
53 hdlc->ffbit_shift = 0;
54 hdlc->data_received = 0;
55 hdlc->do_closing = 0;
56 hdlc->ffvalue = 0;
57 if (is_d_channel) {
58 hdlc->dchannel = 1;
59 hdlc->state = HDLC_SEND_FIRST_FLAG;
60 } else {
61 hdlc->dchannel = 0;
62 hdlc->state = HDLC_SEND_FAST_FLAG;
63 hdlc->ffvalue = 0x7e;
64 }
65 hdlc->cbin = 0x7e;
66 hdlc->bit_shift = 0;
67 if(do_adapt56){
68 hdlc->do_adapt56 = 1;
69 hdlc->data_bits = 0;
70 hdlc->state = HDLC_SENDFLAG_B0;
71 } else {
72 hdlc->do_adapt56 = 0;
73 hdlc->data_bits = 8;
74 }
75 hdlc->shift_reg = 0;
76}
77
78/*
79 hdlc_decode - decodes HDLC frames from a transparent bit stream.
80
81 The source buffer is scanned for valid HDLC frames looking for
82 flags (01111110) to indicate the start of a frame. If the start of
83 the frame is found, the bit stuffing is removed (0 after 5 1's).
84 When a new flag is found, the complete frame has been received
85 and the CRC is checked.
86 If a valid frame is found, the function returns the frame length
87 excluding the CRC with the bit HDLC_END_OF_FRAME set.
88 If the beginning of a valid frame is found, the function returns
89 the length.
90 If a framing error is found (too many 1s and not a flag) the function
91 returns the length with the bit HDLC_FRAMING_ERROR set.
92 If a CRC error is found the function returns the length with the
93 bit HDLC_CRC_ERROR set.
94 If the frame length exceeds the destination buffer size, the function
95 returns the length with the bit HDLC_LENGTH_ERROR set.
96
97 src - source buffer
98 slen - source buffer length
99 count - number of bytes removed (decoded) from the source buffer
100 dst _ destination buffer
101 dsize - destination buffer size
102 returns - number of decoded bytes in the destination buffer and status
103 flag.
104 */
105int hdlc_decode(struct hdlc_vars *hdlc, const unsigned char *src,
106 int slen, int *count, unsigned char *dst, int dsize)
107{
108 int status=0;
109
110 static const unsigned char fast_flag[]={
111 0x00,0x00,0x00,0x20,0x30,0x38,0x3c,0x3e,0x3f
112 };
113
114 static const unsigned char fast_flag_value[]={
115 0x00,0x7e,0xfc,0xf9,0xf3,0xe7,0xcf,0x9f,0x3f
116 };
117
118 static const unsigned char fast_abort[]={
119 0x00,0x00,0x80,0xc0,0xe0,0xf0,0xf8,0xfc,0xfe,0xff
120 };
121
122 *count = slen;
123
124 while(slen > 0){
125 if(hdlc->bit_shift==0){
126 hdlc->cbin = *src++;
127 slen--;
128 hdlc->bit_shift = 8;
129 if(hdlc->do_adapt56){
130 hdlc->bit_shift --;
131 }
132 }
133
134 switch(hdlc->state){
135 case STOPPED:
136 return 0;
137 case HDLC_FAST_IDLE:
138 if(hdlc->cbin == 0xff){
139 hdlc->bit_shift = 0;
140 break;
141 }
142 hdlc->state = HDLC_GET_FLAG_B0;
143 hdlc->hdlc_bits1 = 0;
144 hdlc->bit_shift = 8;
145 break;
146 case HDLC_GET_FLAG_B0:
147 if(!(hdlc->cbin & 0x80)) {
148 hdlc->state = HDLC_GETFLAG_B1A6;
149 hdlc->hdlc_bits1 = 0;
150 } else {
151 if(!hdlc->do_adapt56){
152 if(++hdlc->hdlc_bits1 >=8 ) if(hdlc->bit_shift==1)
153 hdlc->state = HDLC_FAST_IDLE;
154 }
155 }
156 hdlc->cbin<<=1;
157 hdlc->bit_shift --;
158 break;
159 case HDLC_GETFLAG_B1A6:
160 if(hdlc->cbin & 0x80){
161 hdlc->hdlc_bits1++;
162 if(hdlc->hdlc_bits1==6){
163 hdlc->state = HDLC_GETFLAG_B7;
164 }
165 } else {
166 hdlc->hdlc_bits1 = 0;
167 }
168 hdlc->cbin<<=1;
169 hdlc->bit_shift --;
170 break;
171 case HDLC_GETFLAG_B7:
172 if(hdlc->cbin & 0x80) {
173 hdlc->state = HDLC_GET_FLAG_B0;
174 } else {
175 hdlc->state = HDLC_GET_DATA;
176 hdlc->crc = 0xffff;
177 hdlc->shift_reg = 0;
178 hdlc->hdlc_bits1 = 0;
179 hdlc->data_bits = 0;
180 hdlc->data_received = 0;
181 }
182 hdlc->cbin<<=1;
183 hdlc->bit_shift --;
184 break;
185 case HDLC_GET_DATA:
186 if(hdlc->cbin & 0x80){
187 hdlc->hdlc_bits1++;
188 switch(hdlc->hdlc_bits1){
189 case 6:
190 break;
191 case 7:
192 if(hdlc->data_received) {
193 // bad frame
194 status = -HDLC_FRAMING_ERROR;
195 }
196 if(!hdlc->do_adapt56){
197 if(hdlc->cbin==fast_abort[hdlc->bit_shift+1]){
198 hdlc->state = HDLC_FAST_IDLE;
199 hdlc->bit_shift=1;
200 break;
201 }
202 } else {
203 hdlc->state = HDLC_GET_FLAG_B0;
204 }
205 break;
206 default:
207 hdlc->shift_reg>>=1;
208 hdlc->shift_reg |= 0x80;
209 hdlc->data_bits++;
210 break;
211 }
212 } else {
213 switch(hdlc->hdlc_bits1){
214 case 5:
215 break;
216 case 6:
217 if(hdlc->data_received){
218 if (hdlc->dstpos < 2) {
219 status = -HDLC_FRAMING_ERROR;
220 } else if (hdlc->crc != 0xf0b8){
221 // crc error
222 status = -HDLC_CRC_ERROR;
223 } else {
224 // remove CRC
225 hdlc->dstpos -= 2;
226 // good frame
227 status = hdlc->dstpos;
228 }
229 }
230 hdlc->crc = 0xffff;
231 hdlc->shift_reg = 0;
232 hdlc->data_bits = 0;
233 if(!hdlc->do_adapt56){
234 if(hdlc->cbin==fast_flag[hdlc->bit_shift]){
235 hdlc->ffvalue = fast_flag_value[hdlc->bit_shift];
236 hdlc->state = HDLC_FAST_FLAG;
237 hdlc->ffbit_shift = hdlc->bit_shift;
238 hdlc->bit_shift = 1;
239 } else {
240 hdlc->state = HDLC_GET_DATA;
241 hdlc->data_received = 0;
242 }
243 } else {
244 hdlc->state = HDLC_GET_DATA;
245 hdlc->data_received = 0;
246 }
247 break;
248 default:
249 hdlc->shift_reg>>=1;
250 hdlc->data_bits++;
251 break;
252 }
253 hdlc->hdlc_bits1 = 0;
254 }
255 if (status) {
256 hdlc->dstpos = 0;
257 *count -= slen;
258 hdlc->cbin <<= 1;
259 hdlc->bit_shift--;
260 return status;
261 }
262 if(hdlc->data_bits==8){
263 hdlc->data_bits = 0;
264 hdlc->data_received = 1;
265 hdlc->crc = crc_ccitt_byte(hdlc->crc, hdlc->shift_reg);
266
267 // good byte received
268 if (dsize--) {
269 dst[hdlc->dstpos++] = hdlc->shift_reg;
270 } else {
271 // frame too long
272 status = -HDLC_LENGTH_ERROR;
273 hdlc->dstpos = 0;
274 }
275 }
276 hdlc->cbin <<= 1;
277 hdlc->bit_shift--;
278 break;
279 case HDLC_FAST_FLAG:
280 if(hdlc->cbin==hdlc->ffvalue){
281 hdlc->bit_shift = 0;
282 break;
283 } else {
284 if(hdlc->cbin == 0xff){
285 hdlc->state = HDLC_FAST_IDLE;
286 hdlc->bit_shift=0;
287 } else if(hdlc->ffbit_shift==8){
288 hdlc->state = HDLC_GETFLAG_B7;
289 break;
290 } else {
291 hdlc->shift_reg = fast_abort[hdlc->ffbit_shift-1];
292 hdlc->hdlc_bits1 = hdlc->ffbit_shift-2;
293 if(hdlc->hdlc_bits1<0)hdlc->hdlc_bits1 = 0;
294 hdlc->data_bits = hdlc->ffbit_shift-1;
295 hdlc->state = HDLC_GET_DATA;
296 hdlc->data_received = 0;
297 }
298 }
299 break;
300 default:
301 break;
302 }
303 }
304 *count -= slen;
305 return 0;
306}
307
308/*
309 hdlc_encode - encodes HDLC frames to a transparent bit stream.
310
311 The bit stream starts with a beginning flag (01111110). After
312 that each byte is added to the bit stream with bit stuffing added
313 (0 after 5 1's).
314 When the last byte has been removed from the source buffer, the
315 CRC (2 bytes is added) and the frame terminates with the ending flag.
316 For the dchannel, the idle character (all 1's) is also added at the end.
317 If this function is called with empty source buffer (slen=0), flags or
318 idle character will be generated.
319
320 src - source buffer
321 slen - source buffer length
322 count - number of bytes removed (encoded) from source buffer
323 dst _ destination buffer
324 dsize - destination buffer size
325 returns - number of encoded bytes in the destination buffer
326*/
327int hdlc_encode(struct hdlc_vars *hdlc, const unsigned char *src,
328 unsigned short slen, int *count,
329 unsigned char *dst, int dsize)
330{
331 static const unsigned char xfast_flag_value[] = {
332 0x7e,0x3f,0x9f,0xcf,0xe7,0xf3,0xf9,0xfc,0x7e
333 };
334
335 int len = 0;
336
337 *count = slen;
338
339 while (dsize > 0) {
340 if(hdlc->bit_shift==0){
341 if(slen && !hdlc->do_closing){
342 hdlc->shift_reg = *src++;
343 slen--;
344 if (slen == 0)
345 hdlc->do_closing = 1; /* closing sequence, CRC + flag(s) */
346 hdlc->bit_shift = 8;
347 } else {
348 if(hdlc->state == HDLC_SEND_DATA){
349 if(hdlc->data_received){
350 hdlc->state = HDLC_SEND_CRC1;
351 hdlc->crc ^= 0xffff;
352 hdlc->bit_shift = 8;
353 hdlc->shift_reg = hdlc->crc & 0xff;
354 } else if(!hdlc->do_adapt56){
355 hdlc->state = HDLC_SEND_FAST_FLAG;
356 } else {
357 hdlc->state = HDLC_SENDFLAG_B0;
358 }
359 }
360
361 }
362 }
363
364 switch(hdlc->state){
365 case STOPPED:
366 while (dsize--)
367 *dst++ = 0xff;
368
369 return dsize;
370 case HDLC_SEND_FAST_FLAG:
371 hdlc->do_closing = 0;
372 if(slen == 0){
373 *dst++ = hdlc->ffvalue;
374 len++;
375 dsize--;
376 break;
377 }
378 if(hdlc->bit_shift==8){
379 hdlc->cbin = hdlc->ffvalue>>(8-hdlc->data_bits);
380 hdlc->state = HDLC_SEND_DATA;
381 hdlc->crc = 0xffff;
382 hdlc->hdlc_bits1 = 0;
383 hdlc->data_received = 1;
384 }
385 break;
386 case HDLC_SENDFLAG_B0:
387 hdlc->do_closing = 0;
388 hdlc->cbin <<= 1;
389 hdlc->data_bits++;
390 hdlc->hdlc_bits1 = 0;
391 hdlc->state = HDLC_SENDFLAG_B1A6;
392 break;
393 case HDLC_SENDFLAG_B1A6:
394 hdlc->cbin <<= 1;
395 hdlc->data_bits++;
396 hdlc->cbin++;
397 if(++hdlc->hdlc_bits1 == 6)
398 hdlc->state = HDLC_SENDFLAG_B7;
399 break;
400 case HDLC_SENDFLAG_B7:
401 hdlc->cbin <<= 1;
402 hdlc->data_bits++;
403 if(slen == 0){
404 hdlc->state = HDLC_SENDFLAG_B0;
405 break;
406 }
407 if(hdlc->bit_shift==8){
408 hdlc->state = HDLC_SEND_DATA;
409 hdlc->crc = 0xffff;
410 hdlc->hdlc_bits1 = 0;
411 hdlc->data_received = 1;
412 }
413 break;
414 case HDLC_SEND_FIRST_FLAG:
415 hdlc->data_received = 1;
416 if(hdlc->data_bits==8){
417 hdlc->state = HDLC_SEND_DATA;
418 hdlc->crc = 0xffff;
419 hdlc->hdlc_bits1 = 0;
420 break;
421 }
422 hdlc->cbin <<= 1;
423 hdlc->data_bits++;
424 if(hdlc->shift_reg & 0x01)
425 hdlc->cbin++;
426 hdlc->shift_reg >>= 1;
427 hdlc->bit_shift--;
428 if(hdlc->bit_shift==0){
429 hdlc->state = HDLC_SEND_DATA;
430 hdlc->crc = 0xffff;
431 hdlc->hdlc_bits1 = 0;
432 }
433 break;
434 case HDLC_SEND_DATA:
435 hdlc->cbin <<= 1;
436 hdlc->data_bits++;
437 if(hdlc->hdlc_bits1 == 5){
438 hdlc->hdlc_bits1 = 0;
439 break;
440 }
441 if(hdlc->bit_shift==8){
442 hdlc->crc = crc_ccitt_byte(hdlc->crc, hdlc->shift_reg);
443 }
444 if(hdlc->shift_reg & 0x01){
445 hdlc->hdlc_bits1++;
446 hdlc->cbin++;
447 hdlc->shift_reg >>= 1;
448 hdlc->bit_shift--;
449 } else {
450 hdlc->hdlc_bits1 = 0;
451 hdlc->shift_reg >>= 1;
452 hdlc->bit_shift--;
453 }
454 break;
455 case HDLC_SEND_CRC1:
456 hdlc->cbin <<= 1;
457 hdlc->data_bits++;
458 if(hdlc->hdlc_bits1 == 5){
459 hdlc->hdlc_bits1 = 0;
460 break;
461 }
462 if(hdlc->shift_reg & 0x01){
463 hdlc->hdlc_bits1++;
464 hdlc->cbin++;
465 hdlc->shift_reg >>= 1;
466 hdlc->bit_shift--;
467 } else {
468 hdlc->hdlc_bits1 = 0;
469 hdlc->shift_reg >>= 1;
470 hdlc->bit_shift--;
471 }
472 if(hdlc->bit_shift==0){
473 hdlc->shift_reg = (hdlc->crc >> 8);
474 hdlc->state = HDLC_SEND_CRC2;
475 hdlc->bit_shift = 8;
476 }
477 break;
478 case HDLC_SEND_CRC2:
479 hdlc->cbin <<= 1;
480 hdlc->data_bits++;
481 if(hdlc->hdlc_bits1 == 5){
482 hdlc->hdlc_bits1 = 0;
483 break;
484 }
485 if(hdlc->shift_reg & 0x01){
486 hdlc->hdlc_bits1++;
487 hdlc->cbin++;
488 hdlc->shift_reg >>= 1;
489 hdlc->bit_shift--;
490 } else {
491 hdlc->hdlc_bits1 = 0;
492 hdlc->shift_reg >>= 1;
493 hdlc->bit_shift--;
494 }
495 if(hdlc->bit_shift==0){
496 hdlc->shift_reg = 0x7e;
497 hdlc->state = HDLC_SEND_CLOSING_FLAG;
498 hdlc->bit_shift = 8;
499 }
500 break;
501 case HDLC_SEND_CLOSING_FLAG:
502 hdlc->cbin <<= 1;
503 hdlc->data_bits++;
504 if(hdlc->hdlc_bits1 == 5){
505 hdlc->hdlc_bits1 = 0;
506 break;
507 }
508 if(hdlc->shift_reg & 0x01){
509 hdlc->cbin++;
510 }
511 hdlc->shift_reg >>= 1;
512 hdlc->bit_shift--;
513 if(hdlc->bit_shift==0){
514 hdlc->ffvalue = xfast_flag_value[hdlc->data_bits];
515 if(hdlc->dchannel){
516 hdlc->ffvalue = 0x7e;
517 hdlc->state = HDLC_SEND_IDLE1;
518 hdlc->bit_shift = 8-hdlc->data_bits;
519 if(hdlc->bit_shift==0)
520 hdlc->state = HDLC_SEND_FAST_IDLE;
521 } else {
522 if(!hdlc->do_adapt56){
523 hdlc->state = HDLC_SEND_FAST_FLAG;
524 hdlc->data_received = 0;
525 } else {
526 hdlc->state = HDLC_SENDFLAG_B0;
527 hdlc->data_received = 0;
528 }
529 // Finished with this frame, send flags
530 if (dsize > 1) dsize = 1;
531 }
532 }
533 break;
534 case HDLC_SEND_IDLE1:
535 hdlc->do_closing = 0;
536 hdlc->cbin <<= 1;
537 hdlc->cbin++;
538 hdlc->data_bits++;
539 hdlc->bit_shift--;
540 if(hdlc->bit_shift==0){
541 hdlc->state = HDLC_SEND_FAST_IDLE;
542 hdlc->bit_shift = 0;
543 }
544 break;
545 case HDLC_SEND_FAST_IDLE:
546 hdlc->do_closing = 0;
547 hdlc->cbin = 0xff;
548 hdlc->data_bits = 8;
549 if(hdlc->bit_shift == 8){
550 hdlc->cbin = 0x7e;
551 hdlc->state = HDLC_SEND_FIRST_FLAG;
552 } else {
553 *dst++ = hdlc->cbin;
554 hdlc->bit_shift = hdlc->data_bits = 0;
555 len++;
556 dsize = 0;
557 }
558 break;
559 default:
560 break;
561 }
562 if(hdlc->do_adapt56){
563 if(hdlc->data_bits==7){
564 hdlc->cbin <<= 1;
565 hdlc->cbin++;
566 hdlc->data_bits++;
567 }
568 }
569 if(hdlc->data_bits==8){
570 *dst++ = hdlc->cbin;
571 hdlc->data_bits = 0;
572 len++;
573 dsize--;
574 }
575 }
576 *count -= slen;
577
578 return len;
579}
580
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-24 21:38:12 -0500