Asterisk - The Open Source Telephony Project  18.5.0
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 <[email protected]>
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 <[email protected]>
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 
49 static 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 */
66 static 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 */
88 static 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 */
95 static 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 */
124 static 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 
149 static 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 
165 static 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 
222 int 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(;;) {
265 search_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  }
280 search_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 
301 getbyte:
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 : Framming error
360  */
361 
362  *outbyte = a;
364  return 1;
365 }
#define STATE_GET_BYTE
Definition: fskmodem_int.c:47
Asterisk main include file. File version handling, generic pbx functions.
static int ibpdfilter(struct filter_struct *fs, int in)
Definition: fskmodem_int.c:95
#define NBW
Definition: fskmodem_int.c:39
#define STATE_SEARCH_STARTBIT
Definition: fskmodem_int.c:44
int fskmodem_init(fsk_data *fskd)
Definition: fskmodem_int.c:195
int fsk_serial(fsk_data *fskd, short *buffer, int *len, int *outbyte)
Definition: fskmodem_int.c:222
int pllids
Definition: fskmodem_int.h:60
#define STATE_SEARCH_STARTBIT2
Definition: fskmodem_int.c:45
static int iget_sample(short **buffer, int *len)
Definition: fskmodem_int.c:49
FILE * in
Definition: utils/frame.c:33
static int ibpfilter(struct filter_struct *fs, int in)
Definition: fskmodem_int.c:124
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
int instop
Definition: fskmodem_int.h:46
struct filter_struct demod_filter
Definition: fskmodem_int.h:65
int pllispb
Definition: fskmodem_int.h:59
struct filter_struct space_filter
Definition: fskmodem_int.h:64
int pllispb2
Definition: fskmodem_int.h:61
#define NF
Definition: fskmodem_int.c:41
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
#define IGET_SAMPLE
Definition: fskmodem_int.c:58
int f_space_idx
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
static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
Definition: fskmodem_int.c:165
static ENTRY retval
Definition: hsearch.c:50
int f_mark_idx
FSK Modem Support.
enum queue_result id
Definition: app_queue.c:1507
static int idemodulator(fsk_data *fskd, int *retval, int x)
Definition: fskmodem_int.c:149
#define STATE_SEARCH_STARTBIT3
Definition: fskmodem_int.c:46
struct filter_struct mark_filter
Definition: fskmodem_int.h:63
static struct test_val a