Asterisk - The Open Source Telephony Project GIT-master-d856a3e
fskmodem_int.c
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1/*
2 * Asterisk -- An open source telephony toolkit.
3 *
4 * Copyright (C) 1999 - 2005, Digium, Inc.
5 *
6 * Mark Spencer <markster@digium.com>
7 *
8 * Includes code and algorithms from the Zapata library.
9 *
10 * See http://www.asterisk.org for more information about
11 * the Asterisk project. Please do not directly contact
12 * any of the maintainers of this project for assistance;
13 * the project provides a web site, mailing lists and IRC
14 * channels for your use.
15 *
16 * This program is free software, distributed under the terms of
17 * the GNU General Public License Version 2. See the LICENSE file
18 * at the top of the source tree.
19 */
20
21/*! \file
22 *
23 * \brief FSK Modulator/Demodulator
24 *
25 * \author Mark Spencer <markster@digium.com>
26 *
27 * \arg Includes code and algorithms from the Zapata library.
28 *
29 */
30
31/*** MODULEINFO
32 <support_level>core</support_level>
33 ***/
34
35#include "asterisk.h"
36
37#include "asterisk/fskmodem.h"
38
39#define NBW 2
40#define BWLIST {75,800}
41#define NF 6
42#define FLIST {1400,1800,1200,2200,1300,2100}
43
44#define STATE_SEARCH_STARTBIT 0
45#define STATE_SEARCH_STARTBIT2 1
46#define STATE_SEARCH_STARTBIT3 2
47#define STATE_GET_BYTE 3
48
49static inline int iget_sample(short **buffer, int *len)
50{
51 int retval;
52 retval = (int) **buffer;
53 (*buffer)++;
54 (*len)--;
55 return retval;
56}
57
58#define IGET_SAMPLE iget_sample(&buffer, len)
59/*! \brief Coefficients for input filters
60 * Coefficients table, generated by program "mkfilter"
61 * mkfilter is part of the zapatatelephony.org distribution
62 * Format: coef[IDX_FREC][IDX_BW][IDX_COEF]
63 * IDX_COEF = 0 => 1/GAIN
64 * IDX_COEF = 1-6 => Coefficientes y[n]
65*/
66static double coef_in[NF][NBW][8]={
67 { { 1.8229206611e-04,-7.8997325866e-01,2.2401819940e+00,-4.6751353581e+00,5.5080745712e+00,-5.0571565772e+00,2.6215820004e+00,0.0000000000e+00,
68 }, { 9.8532175289e-02,-5.6297236492e-02,3.3146713415e-01,-9.2239200436e-01,1.4844365184e+00,-2.0183258642e+00,2.0074154497e+00,0.0000000000e+00,
69 }, }, { { 1.8229206610e-04,-7.8997325866e-01,7.7191410839e-01,-2.8075643964e+00,1.6948618347e+00,-3.0367273700e+00,9.0333559408e-01,0.0000000000e+00,
70 }, { 9.8531161839e-02,-5.6297236492e-02,1.1421579050e-01,-4.8122536483e-01,4.0121072432e-01,-7.4834487567e-01,6.9170822332e-01,0.0000000000e+00,
71 }, }, { { 1.8229206611e-04,-7.8997325866e-01,2.9003821430e+00,-6.1082779024e+00,7.7169345751e+00,-6.6075999680e+00,3.3941838836e+00,0.0000000000e+00,
72 }, { 9.8539686961e-02,-5.6297236492e-02,4.2915323820e-01,-1.2609358633e+00,2.2399213250e+00,-2.9928879142e+00,2.5990173742e+00,0.0000000000e+00,
73 }, }, { { 1.8229206610e-04,-7.8997325866e-01,-7.7191410839e-01,-2.8075643964e+00,-1.6948618347e+00,-3.0367273700e+00,-9.0333559408e-01,0.0000000000e+00,
74 }, { 9.8531161839e-02,-5.6297236492e-02,-1.1421579050e-01,-4.8122536483e-01,-4.0121072432e-01,-7.4834487567e-01,-6.9170822332e-01,0.0000000000e+00,
75 }, }, { { 1.8229206611e-04,-7.8997325866e-01,2.5782298908e+00,-5.3629717478e+00,6.5890882172e+00,-5.8012914776e+00,3.0171839130e+00,0.0000000000e+00,
76 }, { 9.8534230718e-02,-5.6297236492e-02,3.8148618075e-01,-1.0848760410e+00,1.8441165168e+00,-2.4860666655e+00,2.3103384142e+00,0.0000000000e+00,
77 }, }, { { 1.8229206610e-04,-7.8997325866e-01,-3.8715051001e-01,-2.6192408538e+00,-8.3977994034e-01,-2.8329897913e+00,-4.5306444352e-01,0.0000000000e+00,
78 }, { 9.8531160936e-02,-5.6297236492e-02,-5.7284484199e-02,-4.3673866734e-01,-1.9564766257e-01,-6.2028156584e-01,-3.4692356122e-01,0.0000000000e+00,
79 }, },
80};
81
82/*! \brief Coefficients for output filter
83 * Coefficients table, generated by program "mkfilter"
84 * Format: coef[IDX_BW][IDX_COEF]
85 * IDX_COEF = 0 => 1/GAIN
86 * IDX_COEF = 1-6 => Coefficientes y[n]
87*/
88static double coef_out[NBW][8]={
89 { 1.3868644653e-08,-6.3283665042e-01,4.0895057217e+00,-1.1020074592e+01,1.5850766191e+01,-1.2835109292e+01,5.5477477340e+00,0.0000000000e+00,
90 }, { 3.1262119724e-03,-7.8390522307e-03,8.5209627801e-02,-4.0804129163e-01,1.1157139955e+00,-1.8767603680e+00,1.8916395224e+00,0.0000000000e+00
91 },
92};
93
94/*! Integer Pass Band demodulator filter */
95static inline int ibpdfilter(struct filter_struct * fs, int in)
96{
97 int i,j;
98 int s;
99 int64_t s_interim;
100
101 /* integer filter */
102 s = in * fs->icoefs[0];
103 fs->ixv[(fs->ip + 6) & 7] = s;
104
105 s = (fs->ixv[fs->ip] + fs->ixv[(fs->ip + 6) & 7]) +
106 6 * (fs->ixv[(fs->ip + 1) & 7] + fs->ixv[(fs->ip + 5) & 7]) +
107 15 * (fs->ixv[(fs->ip + 2) & 7] + fs->ixv[(fs->ip + 4) & 7]) +
108 20 * fs->ixv[(fs->ip + 3) & 7];
109
110 for (i = 1, j = fs->ip; i < 7; i++, j++) {
111 /* Promote operation to 64 bit to prevent overflow that occurred in 32 bit) */
112 s_interim = (int64_t)(fs->iyv[j & 7]) *
113 (int64_t)(fs->icoefs[i]) /
114 (int64_t)(1024);
115 s += (int) s_interim;
116 }
117 fs->iyv[j & 7] = s;
118 fs->ip++;
119 fs->ip &= 7;
120 return s;
121}
122
123/*! Integer Band Pass filter */
124static inline int ibpfilter(struct filter_struct * fs, int in)
125{
126 int i, j;
127 int s;
128 int64_t s_interim;
129
130 /* integer filter */
131 s = in * fs->icoefs[0] / 256;
132 fs->ixv[(fs->ip + 6) & 7] = s;
133
134 s = (fs->ixv[(fs->ip + 6) & 7] - fs->ixv[fs->ip])
135 + 3 * (fs->ixv[(fs->ip + 2) & 7] - fs->ixv[(fs->ip + 4) & 7]);
136
137 for (i = 1, j = fs->ip; i < 7; i++, j++) {
138 s_interim = (int64_t)(fs->iyv[j & 7]) *
139 (int64_t)(fs->icoefs[i]) /
140 (int64_t)(256);
141 s += (int) s_interim;
142 }
143 fs->iyv[j & 7] = s;
144 fs->ip++;
145 fs->ip &= 7;
146 return s;
147}
148
149static inline int idemodulator(fsk_data *fskd, int *retval, int x)
150{
151 int is, im, id;
152 int ilin2;
153
154 is = ibpfilter(&fskd->space_filter, x);
155 im = ibpfilter(&fskd->mark_filter, x);
156
157 ilin2 = ((im * im) - (is * is)) / (256 * 256);
158
159 id = ibpdfilter(&fskd->demod_filter, ilin2);
160
161 *retval = id;
162 return 0;
163}
164
165static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
166{
167 /* This function implements a DPLL to synchronize with the bits */
168 int f;
169
170 int ix;
171 /* PLL coeffs are set up in callerid_new */
172 for (f = 0;;) {
173 if (idemodulator(fskd, &ix, IGET_SAMPLE)) return(-1);
174 if ((ix * fskd->xi0) < 0) { /* Transicion */
175 if (!f) {
176 if (fskd->icont < (fskd->pllispb2)) {
177 fskd->icont += fskd->pllids;
178 } else {
179 fskd->icont -= fskd->pllids;
180 }
181 f = 1;
182 }
183 }
184 fskd->xi0 = ix;
185 fskd->icont += 32;
186 if (fskd->icont > fskd->pllispb) {
187 fskd->icont -= fskd->pllispb;
188 break;
189 }
190 }
191 f = (ix > 0) ? 0x80 : 0;
192 return f;
193}
194
196{
197 int i;
198
199 fskd->space_filter.ip = 0;
200 fskd->mark_filter.ip = 0;
201 fskd->demod_filter.ip = 0;
202
203 for ( i = 0 ; i < 7 ; i++ ) {
204 fskd->space_filter.icoefs[i] =
205 coef_in[fskd->f_space_idx][fskd->bw][i] * 256;
206 fskd->space_filter.ixv[i] = 0;;
207 fskd->space_filter.iyv[i] = 0;;
208
209 fskd->mark_filter.icoefs[i] =
210 coef_in[fskd->f_mark_idx][fskd->bw][i] * 256;
211 fskd->mark_filter.ixv[i] = 0;;
212 fskd->mark_filter.iyv[i] = 0;;
213
214 fskd->demod_filter.icoefs[i] =
215 coef_out[fskd->bw][i] * 1024;
216 fskd->demod_filter.ixv[i] = 0;;
217 fskd->demod_filter.iyv[i] = 0;;
218 }
219 return 0;
220}
221
222int fsk_serial(fsk_data *fskd, short *buffer, int *len, int *outbyte)
223{
224 int a;
225 int i, j, n1, r;
226 int samples = 0;
227 int olen;
228 int beginlen = *len;
229 int beginlenx;
230
231 switch (fskd->state) {
232 /* Pick up where we left off */
234 goto search_startbit2;
236 goto search_startbit3;
237 case STATE_GET_BYTE:
238 goto getbyte;
239 }
240 /* We await for start bit */
241 do {
242 /* this was jesus's nice, reasonable, working (at least with RTTY) code
243 to look for the beginning of the start bit. Unfortunately, since TTY/TDD's
244 just start sending a start bit with nothing preceding it at the beginning
245 of a transmission (what a LOSING design), we cant do it this elegantly */
246 /* NOT USED
247 if (demodulator(zap,&x1))
248 return -1;
249 for(;;) {
250 if (demodulator(zap,&x2))
251 return -1;
252 if (x1>0 && x2<0) break;
253 x1=x2;
254 }
255 */
256 /* this is now the imprecise, losing, but functional code to detect the
257 beginning of a start bit in the TDD sceanario. It just looks for sufficient
258 level to maybe, perhaps, guess, maybe that its maybe the beginning of
259 a start bit, perhaps. This whole thing stinks! */
260 beginlenx = beginlen; /* just to avoid unused war warnings */
261 if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE))
262 return -1;
263 samples++;
264 for(;;) {
265search_startbit2:
266 if (*len <= 0) {
268 return 0;
269 }
270 samples++;
271 if (idemodulator(fskd, &fskd->xi2, IGET_SAMPLE))
272 return -1;
273#if 0
274 printf("xi2 = %d ", fskd->xi2);
275#endif
276 if (fskd->xi2 < 512) {
277 break;
278 }
279 }
280search_startbit3:
281 /* We await for 0.5 bits before using DPLL */
282 i = fskd->ispb / 2;
283 if (*len < i) {
285 return 0;
286 }
287 for (; i > 0; i--) {
288 if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE))
289 return(-1);
290#if 0
291 printf("xi1 = %d ", fskd->xi1);
292#endif
293 samples++;
294 }
295
296 /* x1 must be negative (start bit confirmation) */
297
298 } while (fskd->xi1 > 0);
299 fskd->state = STATE_GET_BYTE;
300
301getbyte:
302
303 /* Need at least 80 samples (for 1200) or
304 1320 (for 45.5) to be sure we'll have a byte */
305 if (fskd->nbit < 8) {
306 if (*len < 1320)
307 return 0;
308 } else {
309 if (*len < 80)
310 return 0;
311 }
312
313 /* Now we read the data bits */
314 j = fskd->nbit;
315 for (a = n1 = 0; j; j--) {
316 olen = *len;
317 i = get_bit_raw(fskd, buffer, len);
318 buffer += (olen - *len);
319 if (i == -1)
320 return -1;
321 if (i)
322 n1++;
323 a >>= 1;
324 a |= i;
325 }
326 j = 8 - fskd->nbit;
327 a >>= j;
328
329 /* We read parity bit (if exists) and check parity */
330 if (fskd->parity) {
331 olen = *len;
332 i = get_bit_raw(fskd, buffer, len);
333 buffer += (olen - *len);
334 if (i == -1)
335 return -1;
336 if (i)
337 n1++;
338 if (fskd->parity == 1) { /* parity=1 (even) */
339 if (n1 & 1)
340 a |= 0x100; /* error */
341 } else { /* parity=2 (odd) */
342 if (!(n1 & 1))
343 a |= 0x100; /* error */
344 }
345 }
346
347 /* We read STOP bits. All of them must be 1 */
348
349 for (j = fskd->instop; j; j--) {
350 r = get_bit_raw(fskd, buffer, len);
351 if (r == -1)
352 return -1;
353 if (!r)
354 a |= 0x200;
355 }
356
357 /* And finally we return
358 * Bit 8 : Parity error
359 * Bit 9 : Framing error
360 */
361
362 *outbyte = a;
364 return 1;
365}
enum queue_result id
Definition: app_queue.c:1638
Asterisk main include file. File version handling, generic pbx functions.
FSK Modem Support.
static int ibpfilter(struct filter_struct *fs, int in)
Definition: fskmodem_int.c:124
int fskmodem_init(fsk_data *fskd)
Definition: fskmodem_int.c:195
static int idemodulator(fsk_data *fskd, int *retval, int x)
Definition: fskmodem_int.c:149
static int iget_sample(short **buffer, int *len)
Definition: fskmodem_int.c:49
#define NBW
Definition: fskmodem_int.c:39
static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
Definition: fskmodem_int.c:165
int fsk_serial(fsk_data *fskd, short *buffer, int *len, int *outbyte)
Retrieve a serial byte into outbyte. Buffer is a pointer into a series of shorts and len records the ...
Definition: fskmodem_int.c:222
#define NF
Definition: fskmodem_int.c:41
#define STATE_SEARCH_STARTBIT2
Definition: fskmodem_int.c:45
#define STATE_SEARCH_STARTBIT
Definition: fskmodem_int.c:44
#define STATE_GET_BYTE
Definition: fskmodem_int.c:47
static double coef_in[NF][NBW][8]
Coefficients for input filters Coefficients table, generated by program "mkfilter" mkfilter is part o...
Definition: fskmodem_int.c:66
#define STATE_SEARCH_STARTBIT3
Definition: fskmodem_int.c:46
static int ibpdfilter(struct filter_struct *fs, int in)
Definition: fskmodem_int.c:95
static double coef_out[NBW][8]
Coefficients for output filter Coefficients table, generated by program "mkfilter" Format: coef[IDX_B...
Definition: fskmodem_int.c:88
#define IGET_SAMPLE
Definition: fskmodem_int.c:58
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
static ENTRY retval
Definition: hsearch.c:50
struct filter_struct demod_filter
Definition: fskmodem_int.h:65
struct filter_struct space_filter
Definition: fskmodem_int.h:64
int f_mark_idx
int pllispb2
Definition: fskmodem_int.h:61
int instop
Definition: fskmodem_int.h:46
int pllispb
Definition: fskmodem_int.h:59
int pllids
Definition: fskmodem_int.h:60
struct filter_struct mark_filter
Definition: fskmodem_int.h:63
int f_space_idx
static struct test_val a
FILE * in
Definition: utils/frame.c:33