File: /usr/src/linux/drivers/net/hamradio/soundmodem/sm_psk4800.c
1 /*****************************************************************************/
2
3 /*
4 * sm_psk4800.c -- soundcard radio modem driver, 4800 baud 8PSK modem
5 *
6 * Copyright (C) 1997 Thomas Sailer (sailer@ife.ee.ethz.ch)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 *
22 * Please note that the GPL allows you to use the driver, NOT the radio.
23 * In order to use the radio, you need a license from the communications
24 * authority of your country.
25 *
26 */
27
28 #include "sm.h"
29 #include "sm_tbl_psk4800.h"
30
31 /* --------------------------------------------------------------------- */
32
33 #define DESCRAM_TAP1 0x20000
34 #define DESCRAM_TAP2 0x01000
35 #define DESCRAM_TAP3 0x00001
36
37 #define DESCRAM_TAPSH1 17
38 #define DESCRAM_TAPSH2 12
39 #define DESCRAM_TAPSH3 0
40
41 #define SCRAM_TAP1 0x20000 /* X^17 */
42 #define SCRAM_TAPN 0x00021 /* X^0+X^5 */
43
44 #define SCRAM_SHIFT 17
45
46 /* --------------------------------------------------------------------- */
47
48 struct demod_state_psk48 {
49 /*
50 * input mixer and lowpass
51 */
52 short infi[PSK48_RXF_LEN/2], infq[PSK48_RXF_LEN/2];
53 unsigned int downmixer;
54 int ovrphase;
55 short magi, magq;
56 /*
57 * sampling instant recovery
58 */
59 int pwrhist[5];
60 unsigned int s_phase;
61 int cur_sync;
62 /*
63 * phase recovery
64 */
65 short cur_phase_dev;
66 short last_ph_err;
67 unsigned short pskph;
68 unsigned int phase;
69 unsigned short last_pskph;
70 unsigned char cur_raw, last_raw, rawbits;
71 /*
72 * decoding
73 */
74 unsigned int shreg;
75 unsigned long descram;
76 unsigned int bit_pll;
77 unsigned char last_sample;
78 unsigned int dcd_shreg;
79 int dcd_sum0, dcd_sum1, dcd_sum2;
80 unsigned int dcd_time;
81 };
82
83 struct mod_state_psk48 {
84 unsigned char txbits[PSK48_TXF_NUMSAMPLES];
85 unsigned short txphase;
86 unsigned int shreg;
87 unsigned long scram;
88 const short *tbl;
89 unsigned int txseq;
90 };
91
92 /* --------------------------------------------------------------------- */
93
94 static void modulator_4800_u8(struct sm_state *sm, unsigned char *buf, unsigned int buflen)
95 {
96 struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
97 int i, j;
98 int si, sq;
99
100 for (; buflen > 0; buflen--, buf++) {
101 if (!st->txseq++) {
102 memmove(st->txbits+1, st->txbits,
103 sizeof(st->txbits)-sizeof(st->txbits[0]));
104 for (i = 0; i < 3; i++) {
105 if (st->shreg <= 1)
106 st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
107 st->scram = (st->scram << 1) |
108 (st->shreg & 1);
109 st->shreg >>= 1;
110 if (st->scram & SCRAM_TAP1)
111 st->scram ^= SCRAM_TAPN;
112 }
113 j = (st->scram >> (SCRAM_SHIFT+3)) & 7;
114 st->txbits[0] -= (j ^ (j >> 1));
115 st->txbits[0] &= 7;
116 st->tbl = psk48_tx_table;
117 }
118 if (st->txseq >= PSK48_TXF_OVERSAMPLING)
119 st->txseq = 0;
120 for (j = si = sq = 0; j < PSK48_TXF_NUMSAMPLES; j++, st->tbl += 16) {
121 si += st->tbl[st->txbits[j]];
122 sq += st->tbl[st->txbits[j]+8];
123 }
124 *buf = ((si*COS(st->txphase)+ sq*SIN(st->txphase)) >> 23) + 0x80;
125 st->txphase = (st->txphase + PSK48_PHASEINC) & 0xffffu;
126 }
127 }
128
129 /* --------------------------------------------------------------------- */
130
131 static void modulator_4800_s16(struct sm_state *sm, short *buf, unsigned int buflen)
132 {
133 struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
134 int i, j;
135 int si, sq;
136
137 for (; buflen > 0; buflen--, buf++) {
138 if (!st->txseq++) {
139 memmove(st->txbits+1, st->txbits,
140 sizeof(st->txbits)-sizeof(st->txbits[0]));
141 for (i = 0; i < 3; i++) {
142 if (st->shreg <= 1)
143 st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
144 st->scram = (st->scram << 1) |
145 (st->shreg & 1);
146 st->shreg >>= 1;
147 if (st->scram & SCRAM_TAP1)
148 st->scram ^= SCRAM_TAPN;
149 }
150 j = (st->scram >> (SCRAM_SHIFT+3)) & 7;
151 st->txbits[0] -= (j ^ (j >> 1));
152 st->txbits[0] &= 7;
153 st->tbl = psk48_tx_table;
154 }
155 if (st->txseq >= PSK48_TXF_OVERSAMPLING)
156 st->txseq = 0;
157 for (j = si = sq = 0; j < PSK48_TXF_NUMSAMPLES; j++, st->tbl += 16) {
158 si += st->tbl[st->txbits[j]];
159 sq += st->tbl[st->txbits[j]+8];
160 }
161 *buf = (si*COS(st->txphase)+ sq*SIN(st->txphase)) >> 15;
162 st->txphase = (st->txphase + PSK48_PHASEINC) & 0xffffu;
163 }
164 }
165
166 /* --------------------------------------------------------------------- */
167
168 static __inline__ unsigned short tbl_atan(short q, short i)
169 {
170 short tmp;
171 unsigned short argoffs = 0;
172
173 if (i == 0 && q == 0)
174 return 0;
175 switch (((q < 0) << 1) | (i < 0)) {
176 case 0:
177 break;
178 case 1:
179 tmp = q;
180 q = -i;
181 i = tmp;
182 argoffs = 0x4000;
183 break;
184 case 3:
185 q = -q;
186 i = -i;
187 argoffs = 0x8000;
188 break;
189 case 2:
190 tmp = -q;
191 q = i;
192 i = tmp;
193 argoffs = 0xc000;
194 break;
195 }
196 if (q > i) {
197 tmp = i / q * ATAN_TABLEN;
198 return (argoffs+0x4000-atan_tab[((i<<15)/q*ATAN_TABLEN>>15)])
199 &0xffffu;
200 }
201 return (argoffs+atan_tab[((q<<15)/i*ATAN_TABLEN)>>15])&0xffffu;
202 }
203
204 #define ATAN(q,i) tbl_atan(q, i)
205
206 /* --------------------------------------------------------------------- */
207
208 static void demod_psk48_baseband(struct sm_state *sm, struct demod_state_psk48 *st,
209 short vali, short valq)
210 {
211 int i, j;
212
213 st->magi = vali;
214 st->magq = valq;
215 memmove(st->pwrhist+1, st->pwrhist,
216 sizeof(st->pwrhist)-sizeof(st->pwrhist[0]));
217 st->pwrhist[0] = st->magi * st->magi +
218 st->magq * st->magq;
219 st->cur_sync = ((st->pwrhist[4] >> 2) > st->pwrhist[2] &&
220 (st->pwrhist[0] >> 2) > st->pwrhist[2] &&
221 st-> pwrhist[3] > st->pwrhist[2] &&
222 st->pwrhist[1] > st->pwrhist[2]);
223 st->s_phase &= 0xffff;
224 st->s_phase += PSK48_SPHASEINC;
225 st->dcd_shreg <<= 1;
226 if (st->cur_sync) {
227 if (st->s_phase >= (0x8000 + 5*PSK48_SPHASEINC/2))
228 st->s_phase -= PSK48_SPHASEINC/6;
229 else
230 st->s_phase += PSK48_SPHASEINC/6;
231 st->dcd_sum0 = 4*hweight8(st->dcd_shreg & 0xf8)-
232 hweight16(st->dcd_shreg & 0x1f00);
233 }
234 if ((--st->dcd_time) <= 0) {
235 hdlcdrv_setdcd(&sm->hdrv, (st->dcd_sum0 + st->dcd_sum1 +
236 st->dcd_sum2) < 0);
237 st->dcd_sum2 = st->dcd_sum1;
238 st->dcd_sum1 = st->dcd_sum0;
239 st->dcd_sum0 = 2; /* slight bias */
240 st->dcd_time = 240;
241 }
242 if (st->s_phase < 0x10000)
243 return;
244 /*
245 * sample one constellation
246 */
247 st->last_pskph = st->pskph;
248 st->pskph = (ATAN(st->magq, st->magi)-
249 st->phase) & 0xffffu;
250 st->last_ph_err = (st->pskph & 0x1fffu) - 0x1000;
251 st->phase += st->last_ph_err/16;
252 st->last_raw = st->cur_raw;
253 st->cur_raw = ((st->pskph >> 13) & 7);
254 i = (st->cur_raw - st->last_raw) & 7;
255 st->rawbits = i ^ (i >> 1) ^ (i >> 2);
256 st->descram = (st->descram << 3) | (st->rawbits);
257 hdlcdrv_channelbit(&sm->hdrv, st->descram & 4);
258 hdlcdrv_channelbit(&sm->hdrv, st->descram & 2);
259 hdlcdrv_channelbit(&sm->hdrv, st->descram & 1);
260 i = (((st->descram >> DESCRAM_TAPSH1) & 7) ^
261 ((st->descram >> DESCRAM_TAPSH2) & 7) ^
262 ((st->descram >> DESCRAM_TAPSH3) & 7));
263 for (j = 4; j; j >>= 1) {
264 st->shreg >>= 1;
265 st->shreg |= (!!(i & j)) << 16;
266 if (st->shreg & 1) {
267 hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
268 st->shreg = 0x10000;
269 }
270 }
271
272 #if 0
273 st->dcd_shreg <<= 1;
274 st->bit_pll += 0x4000;
275 curbit = (*buf >= 0x80);
276 if (st->last_sample ^ curbit) {
277 st->dcd_shreg |= 1;
278 st->bit_pll += pll_corr
279 [st->bit_pll < 0xa000];
280 st->dcd_sum0 += 8 *
281 hweight8(st->dcd_shreg & 0x0c) -
282 !!(st->dcd_shreg & 0x10);
283 }
284 st->last_sample = curbit;
285 hdlcdrv_channelbit(&sm->hdrv, st->last_sample);
286 if ((--st->dcd_time) <= 0) {
287 hdlcdrv_setdcd(&sm->hdrv, (st->dcd_sum0 +
288 st->dcd_sum1 +
289 st->dcd_sum2) < 0);
290 st->dcd_sum2 = st->dcd_sum1;
291 st->dcd_sum1 = st->dcd_sum0;
292 st->dcd_sum0 = 2; /* slight bias */
293 st->dcd_time = 240;
294 }
295 if (st->bit_pll >= 0x10000) {
296 st->bit_pll &= 0xffffu;
297 st->descram = (st->descram << 1) | curbit;
298 descx = st->descram ^ (st->descram >> 1);
299 descx ^= ((descx >> DESCRAM_TAPSH1) ^
300 (descx >> DESCRAM_TAPSH2));
301 st->shreg >>= 1;
302 st->shreg |= (!(descx & 1)) << 16;
303 if (st->shreg & 1) {
304 hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
305 st->shreg = 0x10000;
306 }
307 diag_trigger(sm);
308 }
309 diag_add_one(sm, ((short)(*buf - 0x80)) << 8);
310 #endif
311
312 diag_trigger(sm);
313 diag_add_constellation(sm, (vali*COS(st->phase)+ valq*SIN(st->phase)) >> 13,
314 (valq*COS(st->phase) - vali*SIN(st->phase)) >> 13);
315 }
316
317 /* --------------------------------------------------------------------- */
318
319 static void demodulator_4800_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)
320 {
321 struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
322 int i, si, sq;
323 const short *coeff;
324
325 for (; buflen > 0; buflen--, buf++) {
326 memmove(st->infi+1, st->infi,
327 sizeof(st->infi)-sizeof(st->infi[0]));
328 memmove(st->infq+1, st->infq,
329 sizeof(st->infq)-sizeof(st->infq[0]));
330 si = *buf;
331 si &= 0xff;
332 si -= 128;
333 diag_add_one(sm, si << 8);
334 st->infi[0] = (si * COS(st->downmixer))>>7;
335 st->infq[0] = (si * SIN(st->downmixer))>>7;
336 st->downmixer = (st->downmixer-PSK48_PHASEINC)&0xffffu;
337 for (i = si = sq = 0, coeff = psk48_rx_coeff; i < (PSK48_RXF_LEN/2);
338 i++, coeff += 2) {
339 si += st->infi[i] * (*coeff);
340 sq += st->infq[i] * (*coeff);
341 }
342 demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
343 for (i = si = sq = 0, coeff = psk48_rx_coeff + 1; i < (PSK48_RXF_LEN/2);
344 i++, coeff += 2) {
345 si += st->infi[i] * (*coeff);
346 sq += st->infq[i] * (*coeff);
347 }
348 demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
349 }
350 }
351
352 /* --------------------------------------------------------------------- */
353
354 static void demodulator_4800_s16(struct sm_state *sm, const short *buf, unsigned int buflen)
355 {
356 struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
357 int i, si, sq;
358 const short *coeff;
359
360 for (; buflen > 0; buflen--, buf++) {
361 memmove(st->infi+1, st->infi,
362 sizeof(st->infi)-sizeof(st->infi[0]));
363 memmove(st->infq+1, st->infq,
364 sizeof(st->infq)-sizeof(st->infq[0]));
365 si = *buf;
366 diag_add_one(sm, si);
367 st->infi[0] = (si * COS(st->downmixer))>>15;
368 st->infq[0] = (si * SIN(st->downmixer))>>15;
369 st->downmixer = (st->downmixer-PSK48_PHASEINC)&0xffffu;
370 for (i = si = sq = 0, coeff = psk48_rx_coeff; i < (PSK48_RXF_LEN/2);
371 i++, coeff += 2) {
372 si += st->infi[i] * (*coeff);
373 sq += st->infq[i] * (*coeff);
374 }
375 demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
376 for (i = si = sq = 0, coeff = psk48_rx_coeff + 1; i < (PSK48_RXF_LEN/2);
377 i++, coeff += 2) {
378 si += st->infi[i] * (*coeff);
379 sq += st->infq[i] * (*coeff);
380 }
381 demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
382 }
383 }
384
385 /* --------------------------------------------------------------------- */
386
387 static void mod_init_4800(struct sm_state *sm)
388 {
389 struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
390
391 st->scram = 1;
392 }
393
394 /* --------------------------------------------------------------------- */
395
396 static void demod_init_4800(struct sm_state *sm)
397 {
398 struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
399
400 st->dcd_time = 120;
401 st->dcd_sum0 = 2;
402 }
403
404 /* --------------------------------------------------------------------- */
405
406 const struct modem_tx_info sm_psk4800_tx = {
407 "psk4800", sizeof(struct mod_state_psk48),
408 PSK48_SAMPLERATE, 4800,
409 modulator_4800_u8, modulator_4800_s16, mod_init_4800
410 };
411
412 const struct modem_rx_info sm_psk4800_rx = {
413 "psk4800", sizeof(struct demod_state_psk48),
414 PSK48_SAMPLERATE, 4800, 1, PSK48_TXF_OVERSAMPLING,
415 demodulator_4800_u8, demodulator_4800_s16, demod_init_4800
416 };
417
418 /* --------------------------------------------------------------------- */
419