Merge "core/frame: Fix ast_frdup() and ast_frisolate() for empty text frames"
[asterisk/asterisk.git] / main / fskmodem_float.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 <stdio.h>
38
39 #include "asterisk/fskmodem.h"
40
41 #define NBW     2
42 #define BWLIST  {75,800}
43 #define NF      6
44 #define FLIST {1400,1800,1200,2200,1300,2100}
45
46 #define STATE_SEARCH_STARTBIT   0
47 #define STATE_SEARCH_STARTBIT2  1
48 #define STATE_SEARCH_STARTBIT3  2
49 #define STATE_GET_BYTE                  3
50
51 static inline float get_sample(short **buffer, int *len)
52 {
53         float retval;
54         retval = (float) **buffer / 256;
55         (*buffer)++;
56         (*len)--;
57         return retval;
58 };
59
60 #define GET_SAMPLE get_sample(&buffer, len)
61
62 /*! \brief Coefficients for input filters
63  * Coefficients table, generated by program "mkfilter"
64  * mkfilter is part of the zapatatelephony.org distribution
65  * Format: coef[IDX_FREC][IDX_BW][IDX_COEF]
66  * IDX_COEF = 0 =>      1/GAIN
67  * IDX_COEF = 1-6       =>      Coefficientes y[n]
68 */
69 static double coef_in[NF][NBW][8] = {
70  {
71         { 1.8229206611e-04,-7.8997325866e-01,2.2401819940e+00,-4.6751353581e+00,5.5080745712e+00,-5.0571565772e+00,2.6215820004e+00,0.0000000000e+00, },
72         { 9.8532175289e-02,-5.6297236492e-02,3.3146713415e-01,-9.2239200436e-01,1.4844365184e+00,-2.0183258642e+00,2.0074154497e+00,0.0000000000e+00, },
73  },
74  {
75         { 1.8229206610e-04,-7.8997325866e-01,7.7191410839e-01,-2.8075643964e+00,1.6948618347e+00,-3.0367273700e+00,9.0333559408e-01,0.0000000000e+00, },
76         { 9.8531161839e-02,-5.6297236492e-02,1.1421579050e-01,-4.8122536483e-01,4.0121072432e-01,-7.4834487567e-01,6.9170822332e-01,0.0000000000e+00, },
77  },
78  {
79         { 1.8229206611e-04,-7.8997325866e-01,2.9003821430e+00,-6.1082779024e+00,7.7169345751e+00,-6.6075999680e+00,3.3941838836e+00,0.0000000000e+00, },
80         { 9.8539686961e-02,-5.6297236492e-02,4.2915323820e-01,-1.2609358633e+00,2.2399213250e+00,-2.9928879142e+00,2.5990173742e+00,0.0000000000e+00, },
81   },
82   {
83         { 1.8229206610e-04,-7.8997325866e-01,-7.7191410839e-01,-2.8075643964e+00,-1.6948618347e+00,-3.0367273700e+00,-9.0333559408e-01,0.0000000000e+00, },
84         { 9.8531161839e-02,-5.6297236492e-02,-1.1421579050e-01,-4.8122536483e-01,-4.0121072432e-01,-7.4834487567e-01,-6.9170822332e-01,0.0000000000e+00, },
85   },
86   {
87         { 1.8229206611e-04,-7.8997325866e-01,2.5782298908e+00,-5.3629717478e+00,6.5890882172e+00,-5.8012914776e+00,3.0171839130e+00,0.0000000000e+00, },
88         { 9.8534230718e-02,-5.6297236492e-02,3.8148618075e-01,-1.0848760410e+00,1.8441165168e+00,-2.4860666655e+00,2.3103384142e+00,0.0000000000e+00, },
89   },
90   {
91         { 1.8229206610e-04,-7.8997325866e-01,-3.8715051001e-01,-2.6192408538e+00,-8.3977994034e-01,-2.8329897913e+00,-4.5306444352e-01,0.0000000000e+00, },
92         { 9.8531160936e-02,-5.6297236492e-02,-5.7284484199e-02,-4.3673866734e-01,-1.9564766257e-01,-6.2028156584e-01,-3.4692356122e-01,0.0000000000e+00, },
93   },
94 };
95
96 /*! \brief Coefficients for output filter
97  * Coefficients table, generated by program "mkfilter"
98  * Format: coef[IDX_BW][IDX_COEF]
99  * IDX_COEF = 0 =>      1/GAIN
100  * IDX_COEF = 1-6       =>      Coefficientes y[n]
101  */
102 static double coef_out[NBW][8] = {
103         { 1.3868644653e-08,-6.3283665042e-01,4.0895057217e+00,-1.1020074592e+01,1.5850766191e+01,-1.2835109292e+01,5.5477477340e+00,0.0000000000e+00, },
104         { 3.1262119724e-03,-7.8390522307e-03,8.5209627801e-02,-4.0804129163e-01,1.1157139955e+00,-1.8767603680e+00,1.8916395224e+00,0.0000000000e+00, },
105 };
106
107
108 /*! Band-pass filter for MARK frequency */
109 static inline float filterM(fsk_data *fskd,float in)
110 {
111         int i, j;
112         double s;
113         double *pc;
114
115         pc = &coef_in[fskd->f_mark_idx][fskd->bw][0];
116         fskd->fmxv[(fskd->fmp+6)&7] = in*(*pc++);
117
118         s = (fskd->fmxv[(fskd->fmp + 6) & 7] - fskd->fmxv[fskd->fmp]) + 3 * (fskd->fmxv[(fskd->fmp + 2) & 7] - fskd->fmxv[(fskd->fmp + 4) & 7]);
119         for (i = 0, j = fskd->fmp; i < 6; i++, j++)
120                 s += fskd->fmyv[j&7]*(*pc++);
121         fskd->fmyv[j&7] = s;
122         fskd->fmp++;
123         fskd->fmp &= 7;
124         return s;
125 }
126
127 /*! Band-pass filter for SPACE frequency */
128 static inline float filterS(fsk_data *fskd,float in)
129 {
130         int i, j;
131         double s;
132         double *pc;
133
134         pc = &coef_in[fskd->f_space_idx][fskd->bw][0];
135         fskd->fsxv[(fskd->fsp+6)&7] = in*(*pc++);
136
137         s = (fskd->fsxv[(fskd->fsp + 6) & 7] - fskd->fsxv[fskd->fsp]) + 3 * (fskd->fsxv[(fskd->fsp + 2) & 7] - fskd->fsxv[(fskd->fsp + 4) & 7]);
138         for (i = 0, j = fskd->fsp; i < 6; i++, j++)
139                 s += fskd->fsyv[j&7]*(*pc++);
140         fskd->fsyv[j&7] = s;
141         fskd->fsp++;
142         fskd->fsp &= 7;
143         return s;
144 }
145
146 /*! Low-pass filter for demodulated data */
147 static inline float filterL(fsk_data *fskd,float in)
148 {
149         int i, j;
150         double s;
151         double *pc;
152
153         pc = &coef_out[fskd->bw][0];
154         fskd->flxv[(fskd->flp + 6) & 7] = in * (*pc++);
155
156         s = (fskd->flxv[fskd->flp] + fskd->flxv[(fskd->flp+6)&7]) +
157           6  * (fskd->flxv[(fskd->flp+1)&7] + fskd->flxv[(fskd->flp+5)&7]) +
158           15 * (fskd->flxv[(fskd->flp+2)&7] + fskd->flxv[(fskd->flp+4)&7]) +
159           20 *  fskd->flxv[(fskd->flp+3)&7];
160
161         for (i = 0,j = fskd->flp;i<6;i++,j++)
162                 s += fskd->flyv[j&7]*(*pc++);
163         fskd->flyv[j&7] = s;
164         fskd->flp++;
165         fskd->flp &= 7;
166         return s;
167 }
168
169 static inline int demodulator(fsk_data *fskd, float *retval, float x)
170 {
171         float xS,xM;
172
173         fskd->cola_in[fskd->pcola] = x;
174
175         xS = filterS(fskd,x);
176         xM = filterM(fskd,x);
177
178         fskd->cola_filter[fskd->pcola] = xM-xS;
179
180         x = filterL(fskd,xM*xM - xS*xS);
181
182         fskd->cola_demod[fskd->pcola++] = x;
183         fskd->pcola &=  (NCOLA-1);
184
185         *retval = x;
186         return 0;
187 }
188
189 static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
190 {
191         /* This function implements a DPLL to synchronize with the bits */
192         float x,spb,spb2,ds;
193         int f;
194
195         spb = fskd->spb;
196         if (fskd->spb == 7)
197                 spb = 8000.0 / 1200.0;
198         ds = spb/32.;
199         spb2 = spb/2.;
200
201         for (f = 0;;) {
202                 if (demodulator(fskd, &x, GET_SAMPLE))
203                         return -1;
204                 if ((x * fskd->x0) < 0) {       /* Transition */
205                         if (!f) {
206                                 if (fskd->cont<(spb2))
207                                         fskd->cont += ds;
208                                 else
209                                         fskd->cont -= ds;
210                                 f = 1;
211                         }
212                 }
213                 fskd->x0 = x;
214                 fskd->cont += 1.;
215                 if (fskd->cont > spb) {
216                         fskd->cont -= spb;
217                         break;
218                 }
219         }
220         f = (x > 0) ? 0x80 : 0;
221         return f;
222 }
223
224 int fsk_serial(fsk_data *fskd, short *buffer, int *len, int *outbyte)
225 {
226         int a;
227         int i,j,n1,r;
228         int samples = 0;
229         int olen;
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                 /*
247                 if (demodulator(zap,&x1)) return(-1);
248                 for (;;) {
249                         if (demodulator(zap,&x2)) return(-1);
250                         if (x1>0 && x2<0) break;
251                         x1 = x2;
252                 }
253                 */
254                 /* this is now the imprecise, losing, but functional code to detect the
255                 beginning of a start bit in the TDD sceanario. It just looks for sufficient
256                 level to maybe, perhaps, guess, maybe that its maybe the beginning of
257                 a start bit, perhaps. This whole thing stinks! */
258                 if (demodulator(fskd, &fskd->x1, GET_SAMPLE))
259                         return -1;
260                 samples++;
261                 for (;;) {
262 search_startbit2:
263                         if (*len <= 0) {
264                                 fskd->state  =  STATE_SEARCH_STARTBIT2;
265                                 return 0;
266                         }
267                         samples++;
268                         if (demodulator(fskd, &fskd->x2, GET_SAMPLE))
269                                 return(-1);
270 #if 0
271                         printf("x2  =  %5.5f ", fskd->x2);
272 #endif
273                         if (fskd->x2 < -0.5)
274                                 break;
275                 }
276 search_startbit3:
277                 /* We await for 0.5 bits before using DPLL */
278                 i = fskd->spb/2;
279                 if (*len < i) {
280                         fskd->state = STATE_SEARCH_STARTBIT3;
281                         return 0;
282                 }
283                 for (; i>0; i--) {
284                         if (demodulator(fskd, &fskd->x1, GET_SAMPLE))
285                                 return(-1);
286 #if 0
287                         printf("x1 = %5.5f ", fskd->x1);
288 #endif
289                         samples++;
290                 }
291
292                 /* x1 must be negative (start bit confirmation) */
293
294         } while (fskd->x1 > 0);
295         fskd->state = STATE_GET_BYTE;
296
297 getbyte:
298
299         /* Need at least 80 samples (for 1200) or
300                 1320 (for 45.5) to be sure we'll have a byte */
301         if (fskd->nbit < 8) {
302                 if (*len < 1320)
303                         return 0;
304         } else {
305                 if (*len < 80)
306                         return 0;
307         }
308         /* Now we read the data bits */
309         j = fskd->nbit;
310         for (a = n1 = 0; j; j--) {
311                 olen = *len;
312                 i = get_bit_raw(fskd, buffer, len);
313                 buffer += (olen - *len);
314                 if (i == -1)
315                         return(-1);
316                 if (i)
317                         n1++;
318                 a >>= 1;
319                 a |= i;
320         }
321         j = 8-fskd->nbit;
322         a >>= j;
323
324         /* We read parity bit (if exists) and check parity */
325         if (fskd->parity) {
326                 olen = *len;
327                 i = get_bit_raw(fskd, buffer, len);
328                 buffer += (olen - *len);
329                 if (i == -1)
330                         return(-1);
331                 if (i)
332                         n1++;
333                 if (fskd->parity == 1) {        /* parity=1 (even) */
334                         if (n1&1)
335                                 a |= 0x100;             /* error */
336                 } else {                        /* parity=2 (odd) */
337                         if (!(n1&1))
338                                 a |= 0x100;     /* error */
339                 }
340         }
341
342         /* We read STOP bits. All of them must be 1 */
343
344         for (j = fskd->nstop;j;j--) {
345                 r = get_bit_raw(fskd, buffer, len);
346                 if (r == -1)
347                         return(-1);
348                 if (!r)
349                         a |= 0x200;
350         }
351
352         /* And finally we return  */
353         /* Bit 8 : Parity error */
354         /* Bit 9 : Framming error*/
355
356         *outbyte = a;
357         fskd->state = STATE_SEARCH_STARTBIT;
358         return 1;
359 }