Merge "Revert "PJSIP_CONTACT: add missing argument documentation""
[asterisk/asterisk.git] / main / fskmodem_int.c
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
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
195 int fskmodem_init(fsk_data *fskd)
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 */
233         case STATE_SEARCH_STARTBIT2:
234                 goto search_startbit2;
235         case STATE_SEARCH_STARTBIT3:
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) {
267                                 fskd->state = STATE_SEARCH_STARTBIT2;
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) {
284                         fskd->state = STATE_SEARCH_STARTBIT3;
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;
363         fskd->state = STATE_SEARCH_STARTBIT;
364         return 1;
365 }