File: /usr/src/linux/drivers/net/hamradio/soundmodem/sm_afsk2666.c
1 /*****************************************************************************/
2
3 /*
4 * sm_afsk2666.c -- soundcard radio modem driver, 2666 baud AFSK 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_afsk2666.h"
30
31 /* --------------------------------------------------------------------- */
32
33 struct demod_state_afsk26 {
34 unsigned int shreg;
35 unsigned long descram;
36 int dem_sum[8];
37 int dem_sum_mean;
38 int dem_cnt;
39 unsigned int bit_pll;
40 unsigned char last_sample;
41 unsigned int dcd_shreg;
42 int dcd_sum0, dcd_sum1, dcd_sum2;
43 unsigned int dcd_time;
44 };
45
46 struct mod_state_afsk26 {
47 unsigned int shreg;
48 unsigned long scram;
49 unsigned int bit_pll;
50 unsigned int phinc;
51 unsigned int tx_seq;
52 };
53
54 /* --------------------------------------------------------------------- */
55
56 #define DESCRAM_TAP1 0x20000
57 #define DESCRAM_TAP2 0x01000
58 #define DESCRAM_TAP3 0x00001
59
60 #define DESCRAM_TAPSH1 17
61 #define DESCRAM_TAPSH2 12
62 #define DESCRAM_TAPSH3 0
63
64 #define SCRAM_TAP1 0x20000 /* X^17 */
65 #define SCRAM_TAPN 0x00021 /* X^0+X^5 */
66
67 /* --------------------------------------------------------------------- */
68
69 static void modulator_2666_u8(struct sm_state *sm, unsigned char *buf, unsigned int buflen)
70 {
71 struct mod_state_afsk26 *st = (struct mod_state_afsk26 *)(&sm->m);
72
73 for (; buflen > 0; buflen--, buf++) {
74 if (!st->tx_seq++) {
75 if (st->shreg <= 1)
76 st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
77 st->scram = ((st->scram << 1) | (st->scram & 1));
78 st->scram ^= (!(st->shreg & 1));
79 st->shreg >>= 1;
80 if (st->scram & (SCRAM_TAP1 << 1))
81 st->scram ^= SCRAM_TAPN << 1;
82 st->phinc = afsk26_carfreq[!(st->scram & (SCRAM_TAP1 << 2))];
83 }
84 if (st->tx_seq >= 6)
85 st->tx_seq = 0;
86 *buf = OFFSCOS(st->bit_pll);
87 st->bit_pll += st->phinc;
88 }
89 }
90
91 /* --------------------------------------------------------------------- */
92
93 static void modulator_2666_s16(struct sm_state *sm, short *buf, unsigned int buflen)
94 {
95 struct mod_state_afsk26 *st = (struct mod_state_afsk26 *)(&sm->m);
96
97 for (; buflen > 0; buflen--, buf++) {
98 if (!st->tx_seq++) {
99 if (st->shreg <= 1)
100 st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
101 st->scram = ((st->scram << 1) | (st->scram & 1));
102 st->scram ^= (!(st->shreg & 1));
103 st->shreg >>= 1;
104 if (st->scram & (SCRAM_TAP1 << 1))
105 st->scram ^= SCRAM_TAPN << 1;
106 st->phinc = afsk26_carfreq[!(st->scram & (SCRAM_TAP1 << 2))];
107 }
108 if (st->tx_seq >= 6)
109 st->tx_seq = 0;
110 *buf = COS(st->bit_pll);
111 st->bit_pll += st->phinc;
112 }
113 }
114
115 /* --------------------------------------------------------------------- */
116
117 extern __inline__ int convolution12_u8(const unsigned char *st, const int *coeff, int csum)
118 {
119 int sum = -0x80 * csum;
120
121 sum += (st[0] * coeff[0]);
122 sum += (st[-1] * coeff[1]);
123 sum += (st[-2] * coeff[2]);
124 sum += (st[-3] * coeff[3]);
125 sum += (st[-4] * coeff[4]);
126 sum += (st[-5] * coeff[5]);
127 sum += (st[-6] * coeff[6]);
128 sum += (st[-7] * coeff[7]);
129 sum += (st[-8] * coeff[8]);
130 sum += (st[-9] * coeff[9]);
131 sum += (st[-10] * coeff[10]);
132 sum += (st[-11] * coeff[11]);
133
134 return sum;
135 }
136
137 extern __inline__ int convolution12_s16(const short *st, const int *coeff, int csum)
138 {
139 int sum = 0;
140
141 sum += (st[0] * coeff[0]);
142 sum += (st[-1] * coeff[1]);
143 sum += (st[-2] * coeff[2]);
144 sum += (st[-3] * coeff[3]);
145 sum += (st[-4] * coeff[4]);
146 sum += (st[-5] * coeff[5]);
147 sum += (st[-6] * coeff[6]);
148 sum += (st[-7] * coeff[7]);
149 sum += (st[-8] * coeff[8]);
150 sum += (st[-9] * coeff[9]);
151 sum += (st[-10] * coeff[10]);
152 sum += (st[-11] * coeff[11]);
153
154 sum >>= 8;
155 return sum;
156 }
157
158 /* ---------------------------------------------------------------------- */
159
160 #if 0
161 static int binexp(unsigned int i)
162 {
163 int ret = 31;
164
165 if (!i)
166 return 0;
167 if (i < 0x10000LU) {
168 i <<= 16;
169 ret -= 16;
170 }
171 if (i < 0x1000000LU) {
172 i <<= 8;
173 ret -= 8;
174 }
175 if (i < 0x10000000LU) {
176 i <<= 4;
177 ret -= 4;
178 }
179 if (i < 0x40000000LU) {
180 i <<= 2;
181 ret -= 2;
182 }
183 if (i < 0x80000000LU)
184 ret -= 1;
185 return ret;
186 }
187
188 static const sqrt_tab[16] = {
189 00000, 16384, 23170, 28378, 32768, 36636, 40132, 43348,
190 46341, 49152, 51811, 54340, 56756, 59073, 61303, 63455
191 };
192
193
194 static unsigned int int_sqrt_approx(unsigned int i)
195 {
196 unsigned int j;
197
198 if (i < 16)
199 return sqrt_tab[i] >> 14;
200 j = binexp(i) >> 1;
201 i >>= (j * 2 - 2);
202 return (sqrt_tab[i & 0xf] << j) >> 15;
203 }
204 #endif
205
206 /* --------------------------------------------------------------------- */
207
208 extern unsigned int est_pwr(int i, int q)
209 {
210 unsigned int ui = abs(i);
211 unsigned int uq = abs(q);
212
213 if (uq > ui) {
214 unsigned int tmp;
215 tmp = ui;
216 ui = uq;
217 uq = tmp;
218 }
219 if (uq > (ui >> 1))
220 return 7*(ui>>3) + 9*(uq>>4);
221 else
222 return ui + (uq>>2);
223 }
224
225 /* --------------------------------------------------------------------- */
226
227 static void demod_one_sample(struct sm_state *sm, struct demod_state_afsk26 *st, int curval,
228 int loi, int loq, int hii, int hiq)
229 {
230 static const int pll_corr[2] = { -0xa00, 0xa00 };
231 unsigned char curbit;
232 unsigned int descx;
233 int val;
234
235 /*
236 * estimate power
237 */
238 val = est_pwr(hii, hiq) - est_pwr(loi, loq);
239 /*
240 * estimate center value
241 */
242 st->dem_sum[0] += val >> 8;
243 if ((++st->dem_cnt) >= 256) {
244 st->dem_cnt = 0;
245 st->dem_sum_mean = (st->dem_sum[0]+st->dem_sum[1]+
246 st->dem_sum[2]+st->dem_sum[3]+
247 st->dem_sum[4]+st->dem_sum[5]+
248 st->dem_sum[6]+st->dem_sum[7]) >> 3;
249 memmove(st->dem_sum+1, st->dem_sum,
250 sizeof(st->dem_sum)-sizeof(st->dem_sum[0]));
251 st->dem_sum[0] = 0;
252 }
253 /*
254 * decision and bit clock regen
255 */
256 val -= st->dem_sum_mean;
257 diag_add(sm, curval, val);
258
259 st->dcd_shreg <<= 1;
260 st->bit_pll += 0x1555;
261 curbit = (val > 0);
262 if (st->last_sample ^ curbit) {
263 st->dcd_shreg |= 1;
264 st->bit_pll += pll_corr[st->bit_pll < (0x8000+0x1555)];
265 st->dcd_sum0 += 4*hweight8(st->dcd_shreg & 0x1e) -
266 hweight16(st->dcd_shreg & 0xfe00);
267 }
268 st->last_sample = curbit;
269 hdlcdrv_channelbit(&sm->hdrv, curbit);
270 if ((--st->dcd_time) <= 0) {
271 hdlcdrv_setdcd(&sm->hdrv, (st->dcd_sum0 + st->dcd_sum1 +
272 st->dcd_sum2) < 0);
273 st->dcd_sum2 = st->dcd_sum1;
274 st->dcd_sum1 = st->dcd_sum0;
275 st->dcd_sum0 = 2; /* slight bias */
276 st->dcd_time = 400;
277 }
278 if (st->bit_pll >= 0x10000) {
279 st->bit_pll &= 0xffffu;
280 st->descram = (st->descram << 1) | curbit;
281 descx = st->descram ^ (st->descram >> 1);
282 descx ^= ((descx >> DESCRAM_TAPSH1) ^
283 (descx >> DESCRAM_TAPSH2));
284 st->shreg >>= 1;
285 st->shreg |= (!(descx & 1)) << 16;
286 if (st->shreg & 1) {
287 hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
288 st->shreg = 0x10000;
289 }
290 diag_trigger(sm);
291 }
292 }
293
294 /* --------------------------------------------------------------------- */
295
296 static void demodulator_2666_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)
297 {
298 struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
299
300 for (; buflen > 0; buflen--, buf++) {
301 demod_one_sample(sm, st, (*buf-0x80)<<8,
302 convolution12_u8(buf, afsk26_dem_tables[0][0].i, AFSK26_DEM_SUM_I_0_0),
303 convolution12_u8(buf, afsk26_dem_tables[0][0].q, AFSK26_DEM_SUM_Q_0_0),
304 convolution12_u8(buf, afsk26_dem_tables[0][1].i, AFSK26_DEM_SUM_I_0_1),
305 convolution12_u8(buf, afsk26_dem_tables[0][1].q, AFSK26_DEM_SUM_Q_0_1));
306 demod_one_sample(sm, st, (*buf-0x80)<<8,
307 convolution12_u8(buf, afsk26_dem_tables[1][0].i, AFSK26_DEM_SUM_I_1_0),
308 convolution12_u8(buf, afsk26_dem_tables[1][0].q, AFSK26_DEM_SUM_Q_1_0),
309 convolution12_u8(buf, afsk26_dem_tables[1][1].i, AFSK26_DEM_SUM_I_1_1),
310 convolution12_u8(buf, afsk26_dem_tables[1][1].q, AFSK26_DEM_SUM_Q_1_1));
311 }
312 }
313
314 /* --------------------------------------------------------------------- */
315
316 static void demodulator_2666_s16(struct sm_state *sm, const short *buf, unsigned int buflen)
317 {
318 struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
319
320 for (; buflen > 0; buflen--, buf++) {
321 demod_one_sample(sm, st, *buf,
322 convolution12_s16(buf, afsk26_dem_tables[0][0].i, AFSK26_DEM_SUM_I_0_0),
323 convolution12_s16(buf, afsk26_dem_tables[0][0].q, AFSK26_DEM_SUM_Q_0_0),
324 convolution12_s16(buf, afsk26_dem_tables[0][1].i, AFSK26_DEM_SUM_I_0_1),
325 convolution12_s16(buf, afsk26_dem_tables[0][1].q, AFSK26_DEM_SUM_Q_0_1));
326 demod_one_sample(sm, st, *buf,
327 convolution12_s16(buf, afsk26_dem_tables[1][0].i, AFSK26_DEM_SUM_I_1_0),
328 convolution12_s16(buf, afsk26_dem_tables[1][0].q, AFSK26_DEM_SUM_Q_1_0),
329 convolution12_s16(buf, afsk26_dem_tables[1][1].i, AFSK26_DEM_SUM_I_1_1),
330 convolution12_s16(buf, afsk26_dem_tables[1][1].q, AFSK26_DEM_SUM_Q_1_1));
331 }
332 }
333
334 /* --------------------------------------------------------------------- */
335
336 static void demod_init_2666(struct sm_state *sm)
337 {
338 struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
339
340 st->dcd_time = 400;
341 st->dcd_sum0 = 2;
342 }
343
344 /* --------------------------------------------------------------------- */
345
346 const struct modem_tx_info sm_afsk2666_tx = {
347 "afsk2666", sizeof(struct mod_state_afsk26), AFSK26_SAMPLERATE, 2666,
348 modulator_2666_u8, modulator_2666_s16, NULL
349 };
350
351 const struct modem_rx_info sm_afsk2666_rx = {
352 "afsk2666", sizeof(struct demod_state_afsk26), AFSK26_SAMPLERATE, 2666, 12, 6,
353 demodulator_2666_u8, demodulator_2666_s16, demod_init_2666
354 };
355
356 /* --------------------------------------------------------------------- */
357