Asterisk - The Open Source Telephony Project GIT-master-d856a3e
fskmodem_float.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 <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
51static 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*/
69static 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 */
102static 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 */
109static 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 */
128static 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 */
147static 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
169static 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
189static 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
224int 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 */
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 /*
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 (;;) {
262search_startbit2:
263 if (*len <= 0) {
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 }
276search_startbit3:
277 /* We await for 0.5 bits before using DPLL */
278 i = fskd->spb/2;
279 if (*len < i) {
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
297getbyte:
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 : Framing error*/
355
356 *outbyte = a;
358 return 1;
359}
Asterisk main include file. File version handling, generic pbx functions.
FSK Modem Support.
#define NBW
static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
static float filterM(fsk_data *fskd, float in)
static float get_sample(short **buffer, int *len)
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 ...
static int demodulator(fsk_data *fskd, float *retval, float x)
#define NF
#define STATE_SEARCH_STARTBIT2
static float filterL(fsk_data *fskd, float in)
#define STATE_SEARCH_STARTBIT
#define STATE_GET_BYTE
#define GET_SAMPLE
static double coef_in[NF][NBW][8]
Coefficients for input filters Coefficients table, generated by program "mkfilter" mkfilter is part o...
#define STATE_SEARCH_STARTBIT3
static float filterS(fsk_data *fskd, float in)
static double coef_out[NBW][8]
Coefficients for output filter Coefficients table, generated by program "mkfilter" Format: coef[IDX_B...
#define NCOLA
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
static ENTRY retval
Definition: hsearch.c:50
double flxv[8]
double fsyv[8]
float cola_in[NCOLA]
int f_mark_idx
double fmyv[8]
double fsxv[8]
float nstop
float cont
float cola_filter[NCOLA]
double fmxv[8]
double flyv[8]
float cola_demod[NCOLA]
int f_space_idx
static struct test_val a
FILE * in
Definition: utils/frame.c:33