366 lines
9.9 KiB
C
366 lines
9.9 KiB
C
/*
|
|
* Asterisk -- An open source telephony toolkit.
|
|
*
|
|
* Copyright (C) 1999 - 2005, Digium, Inc.
|
|
*
|
|
* Mark Spencer <markster@digium.com>
|
|
*
|
|
* Includes code and algorithms from the Zapata library.
|
|
*
|
|
* See http://www.asterisk.org for more information about
|
|
* the Asterisk project. Please do not directly contact
|
|
* any of the maintainers of this project for assistance;
|
|
* the project provides a web site, mailing lists and IRC
|
|
* channels for your use.
|
|
*
|
|
* This program is free software, distributed under the terms of
|
|
* the GNU General Public License Version 2. See the LICENSE file
|
|
* at the top of the source tree.
|
|
*/
|
|
|
|
/*! \file
|
|
*
|
|
* \brief FSK Modulator/Demodulator
|
|
*
|
|
* \author Mark Spencer <markster@digium.com>
|
|
*
|
|
* \arg Includes code and algorithms from the Zapata library.
|
|
*
|
|
*/
|
|
|
|
/*** MODULEINFO
|
|
<support_level>core</support_level>
|
|
***/
|
|
|
|
#include "asterisk.h"
|
|
|
|
#include "asterisk/fskmodem.h"
|
|
|
|
#define NBW 2
|
|
#define BWLIST {75,800}
|
|
#define NF 6
|
|
#define FLIST {1400,1800,1200,2200,1300,2100}
|
|
|
|
#define STATE_SEARCH_STARTBIT 0
|
|
#define STATE_SEARCH_STARTBIT2 1
|
|
#define STATE_SEARCH_STARTBIT3 2
|
|
#define STATE_GET_BYTE 3
|
|
|
|
static inline int iget_sample(short **buffer, int *len)
|
|
{
|
|
int retval;
|
|
retval = (int) **buffer;
|
|
(*buffer)++;
|
|
(*len)--;
|
|
return retval;
|
|
}
|
|
|
|
#define IGET_SAMPLE iget_sample(&buffer, len)
|
|
/*! \brief Coefficients for input filters
|
|
* Coefficients table, generated by program "mkfilter"
|
|
* mkfilter is part of the zapatatelephony.org distribution
|
|
* Format: coef[IDX_FREC][IDX_BW][IDX_COEF]
|
|
* IDX_COEF = 0 => 1/GAIN
|
|
* IDX_COEF = 1-6 => Coefficientes y[n]
|
|
*/
|
|
static double coef_in[NF][NBW][8]={
|
|
{ { 1.8229206611e-04,-7.8997325866e-01,2.2401819940e+00,-4.6751353581e+00,5.5080745712e+00,-5.0571565772e+00,2.6215820004e+00,0.0000000000e+00,
|
|
}, { 9.8532175289e-02,-5.6297236492e-02,3.3146713415e-01,-9.2239200436e-01,1.4844365184e+00,-2.0183258642e+00,2.0074154497e+00,0.0000000000e+00,
|
|
}, }, { { 1.8229206610e-04,-7.8997325866e-01,7.7191410839e-01,-2.8075643964e+00,1.6948618347e+00,-3.0367273700e+00,9.0333559408e-01,0.0000000000e+00,
|
|
}, { 9.8531161839e-02,-5.6297236492e-02,1.1421579050e-01,-4.8122536483e-01,4.0121072432e-01,-7.4834487567e-01,6.9170822332e-01,0.0000000000e+00,
|
|
}, }, { { 1.8229206611e-04,-7.8997325866e-01,2.9003821430e+00,-6.1082779024e+00,7.7169345751e+00,-6.6075999680e+00,3.3941838836e+00,0.0000000000e+00,
|
|
}, { 9.8539686961e-02,-5.6297236492e-02,4.2915323820e-01,-1.2609358633e+00,2.2399213250e+00,-2.9928879142e+00,2.5990173742e+00,0.0000000000e+00,
|
|
}, }, { { 1.8229206610e-04,-7.8997325866e-01,-7.7191410839e-01,-2.8075643964e+00,-1.6948618347e+00,-3.0367273700e+00,-9.0333559408e-01,0.0000000000e+00,
|
|
}, { 9.8531161839e-02,-5.6297236492e-02,-1.1421579050e-01,-4.8122536483e-01,-4.0121072432e-01,-7.4834487567e-01,-6.9170822332e-01,0.0000000000e+00,
|
|
}, }, { { 1.8229206611e-04,-7.8997325866e-01,2.5782298908e+00,-5.3629717478e+00,6.5890882172e+00,-5.8012914776e+00,3.0171839130e+00,0.0000000000e+00,
|
|
}, { 9.8534230718e-02,-5.6297236492e-02,3.8148618075e-01,-1.0848760410e+00,1.8441165168e+00,-2.4860666655e+00,2.3103384142e+00,0.0000000000e+00,
|
|
}, }, { { 1.8229206610e-04,-7.8997325866e-01,-3.8715051001e-01,-2.6192408538e+00,-8.3977994034e-01,-2.8329897913e+00,-4.5306444352e-01,0.0000000000e+00,
|
|
}, { 9.8531160936e-02,-5.6297236492e-02,-5.7284484199e-02,-4.3673866734e-01,-1.9564766257e-01,-6.2028156584e-01,-3.4692356122e-01,0.0000000000e+00,
|
|
}, },
|
|
};
|
|
|
|
/*! \brief Coefficients for output filter
|
|
* Coefficients table, generated by program "mkfilter"
|
|
* Format: coef[IDX_BW][IDX_COEF]
|
|
* IDX_COEF = 0 => 1/GAIN
|
|
* IDX_COEF = 1-6 => Coefficientes y[n]
|
|
*/
|
|
static double coef_out[NBW][8]={
|
|
{ 1.3868644653e-08,-6.3283665042e-01,4.0895057217e+00,-1.1020074592e+01,1.5850766191e+01,-1.2835109292e+01,5.5477477340e+00,0.0000000000e+00,
|
|
}, { 3.1262119724e-03,-7.8390522307e-03,8.5209627801e-02,-4.0804129163e-01,1.1157139955e+00,-1.8767603680e+00,1.8916395224e+00,0.0000000000e+00
|
|
},
|
|
};
|
|
|
|
/*! Integer Pass Band demodulator filter */
|
|
static inline int ibpdfilter(struct filter_struct * fs, int in)
|
|
{
|
|
int i,j;
|
|
int s;
|
|
int64_t s_interim;
|
|
|
|
/* integer filter */
|
|
s = in * fs->icoefs[0];
|
|
fs->ixv[(fs->ip + 6) & 7] = s;
|
|
|
|
s = (fs->ixv[fs->ip] + fs->ixv[(fs->ip + 6) & 7]) +
|
|
6 * (fs->ixv[(fs->ip + 1) & 7] + fs->ixv[(fs->ip + 5) & 7]) +
|
|
15 * (fs->ixv[(fs->ip + 2) & 7] + fs->ixv[(fs->ip + 4) & 7]) +
|
|
20 * fs->ixv[(fs->ip + 3) & 7];
|
|
|
|
for (i = 1, j = fs->ip; i < 7; i++, j++) {
|
|
/* Promote operation to 64 bit to prevent overflow that occurred in 32 bit) */
|
|
s_interim = (int64_t)(fs->iyv[j & 7]) *
|
|
(int64_t)(fs->icoefs[i]) /
|
|
(int64_t)(1024);
|
|
s += (int) s_interim;
|
|
}
|
|
fs->iyv[j & 7] = s;
|
|
fs->ip++;
|
|
fs->ip &= 7;
|
|
return s;
|
|
}
|
|
|
|
/*! Integer Band Pass filter */
|
|
static inline int ibpfilter(struct filter_struct * fs, int in)
|
|
{
|
|
int i, j;
|
|
int s;
|
|
int64_t s_interim;
|
|
|
|
/* integer filter */
|
|
s = in * fs->icoefs[0] / 256;
|
|
fs->ixv[(fs->ip + 6) & 7] = s;
|
|
|
|
s = (fs->ixv[(fs->ip + 6) & 7] - fs->ixv[fs->ip])
|
|
+ 3 * (fs->ixv[(fs->ip + 2) & 7] - fs->ixv[(fs->ip + 4) & 7]);
|
|
|
|
for (i = 1, j = fs->ip; i < 7; i++, j++) {
|
|
s_interim = (int64_t)(fs->iyv[j & 7]) *
|
|
(int64_t)(fs->icoefs[i]) /
|
|
(int64_t)(256);
|
|
s += (int) s_interim;
|
|
}
|
|
fs->iyv[j & 7] = s;
|
|
fs->ip++;
|
|
fs->ip &= 7;
|
|
return s;
|
|
}
|
|
|
|
static inline int idemodulator(fsk_data *fskd, int *retval, int x)
|
|
{
|
|
int is, im, id;
|
|
int ilin2;
|
|
|
|
is = ibpfilter(&fskd->space_filter, x);
|
|
im = ibpfilter(&fskd->mark_filter, x);
|
|
|
|
ilin2 = ((im * im) - (is * is)) / (256 * 256);
|
|
|
|
id = ibpdfilter(&fskd->demod_filter, ilin2);
|
|
|
|
*retval = id;
|
|
return 0;
|
|
}
|
|
|
|
static int get_bit_raw(fsk_data *fskd, short *buffer, int *len)
|
|
{
|
|
/* This function implements a DPLL to synchronize with the bits */
|
|
int f;
|
|
|
|
int ix;
|
|
/* PLL coeffs are set up in callerid_new */
|
|
for (f = 0;;) {
|
|
if (idemodulator(fskd, &ix, IGET_SAMPLE)) return(-1);
|
|
if ((ix * fskd->xi0) < 0) { /* Transicion */
|
|
if (!f) {
|
|
if (fskd->icont < (fskd->pllispb2)) {
|
|
fskd->icont += fskd->pllids;
|
|
} else {
|
|
fskd->icont -= fskd->pllids;
|
|
}
|
|
f = 1;
|
|
}
|
|
}
|
|
fskd->xi0 = ix;
|
|
fskd->icont += 32;
|
|
if (fskd->icont > fskd->pllispb) {
|
|
fskd->icont -= fskd->pllispb;
|
|
break;
|
|
}
|
|
}
|
|
f = (ix > 0) ? 0x80 : 0;
|
|
return f;
|
|
}
|
|
|
|
int fskmodem_init(fsk_data *fskd)
|
|
{
|
|
int i;
|
|
|
|
fskd->space_filter.ip = 0;
|
|
fskd->mark_filter.ip = 0;
|
|
fskd->demod_filter.ip = 0;
|
|
|
|
for ( i = 0 ; i < 7 ; i++ ) {
|
|
fskd->space_filter.icoefs[i] =
|
|
coef_in[fskd->f_space_idx][fskd->bw][i] * 256;
|
|
fskd->space_filter.ixv[i] = 0;;
|
|
fskd->space_filter.iyv[i] = 0;;
|
|
|
|
fskd->mark_filter.icoefs[i] =
|
|
coef_in[fskd->f_mark_idx][fskd->bw][i] * 256;
|
|
fskd->mark_filter.ixv[i] = 0;;
|
|
fskd->mark_filter.iyv[i] = 0;;
|
|
|
|
fskd->demod_filter.icoefs[i] =
|
|
coef_out[fskd->bw][i] * 1024;
|
|
fskd->demod_filter.ixv[i] = 0;;
|
|
fskd->demod_filter.iyv[i] = 0;;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int fsk_serial(fsk_data *fskd, short *buffer, int *len, int *outbyte)
|
|
{
|
|
int a;
|
|
int i, j, n1, r;
|
|
int samples = 0;
|
|
int olen;
|
|
int beginlen = *len;
|
|
int beginlenx;
|
|
|
|
switch (fskd->state) {
|
|
/* Pick up where we left off */
|
|
case STATE_SEARCH_STARTBIT2:
|
|
goto search_startbit2;
|
|
case STATE_SEARCH_STARTBIT3:
|
|
goto search_startbit3;
|
|
case STATE_GET_BYTE:
|
|
goto getbyte;
|
|
}
|
|
/* We await for start bit */
|
|
do {
|
|
/* this was jesus's nice, reasonable, working (at least with RTTY) code
|
|
to look for the beginning of the start bit. Unfortunately, since TTY/TDD's
|
|
just start sending a start bit with nothing preceding it at the beginning
|
|
of a transmission (what a LOSING design), we cant do it this elegantly */
|
|
/* NOT USED
|
|
if (demodulator(zap,&x1))
|
|
return -1;
|
|
for(;;) {
|
|
if (demodulator(zap,&x2))
|
|
return -1;
|
|
if (x1>0 && x2<0) break;
|
|
x1=x2;
|
|
}
|
|
*/
|
|
/* this is now the imprecise, losing, but functional code to detect the
|
|
beginning of a start bit in the TDD sceanario. It just looks for sufficient
|
|
level to maybe, perhaps, guess, maybe that its maybe the beginning of
|
|
a start bit, perhaps. This whole thing stinks! */
|
|
beginlenx = beginlen; /* just to avoid unused war warnings */
|
|
if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE))
|
|
return -1;
|
|
samples++;
|
|
for(;;) {
|
|
search_startbit2:
|
|
if (*len <= 0) {
|
|
fskd->state = STATE_SEARCH_STARTBIT2;
|
|
return 0;
|
|
}
|
|
samples++;
|
|
if (idemodulator(fskd, &fskd->xi2, IGET_SAMPLE))
|
|
return -1;
|
|
#if 0
|
|
printf("xi2 = %d ", fskd->xi2);
|
|
#endif
|
|
if (fskd->xi2 < 512) {
|
|
break;
|
|
}
|
|
}
|
|
search_startbit3:
|
|
/* We await for 0.5 bits before using DPLL */
|
|
i = fskd->ispb / 2;
|
|
if (*len < i) {
|
|
fskd->state = STATE_SEARCH_STARTBIT3;
|
|
return 0;
|
|
}
|
|
for (; i > 0; i--) {
|
|
if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE))
|
|
return(-1);
|
|
#if 0
|
|
printf("xi1 = %d ", fskd->xi1);
|
|
#endif
|
|
samples++;
|
|
}
|
|
|
|
/* x1 must be negative (start bit confirmation) */
|
|
|
|
} while (fskd->xi1 > 0);
|
|
fskd->state = STATE_GET_BYTE;
|
|
|
|
getbyte:
|
|
|
|
/* Need at least 80 samples (for 1200) or
|
|
1320 (for 45.5) to be sure we'll have a byte */
|
|
if (fskd->nbit < 8) {
|
|
if (*len < 1320)
|
|
return 0;
|
|
} else {
|
|
if (*len < 80)
|
|
return 0;
|
|
}
|
|
|
|
/* Now we read the data bits */
|
|
j = fskd->nbit;
|
|
for (a = n1 = 0; j; j--) {
|
|
olen = *len;
|
|
i = get_bit_raw(fskd, buffer, len);
|
|
buffer += (olen - *len);
|
|
if (i == -1)
|
|
return -1;
|
|
if (i)
|
|
n1++;
|
|
a >>= 1;
|
|
a |= i;
|
|
}
|
|
j = 8 - fskd->nbit;
|
|
a >>= j;
|
|
|
|
/* We read parity bit (if exists) and check parity */
|
|
if (fskd->parity) {
|
|
olen = *len;
|
|
i = get_bit_raw(fskd, buffer, len);
|
|
buffer += (olen - *len);
|
|
if (i == -1)
|
|
return -1;
|
|
if (i)
|
|
n1++;
|
|
if (fskd->parity == 1) { /* parity=1 (even) */
|
|
if (n1 & 1)
|
|
a |= 0x100; /* error */
|
|
} else { /* parity=2 (odd) */
|
|
if (!(n1 & 1))
|
|
a |= 0x100; /* error */
|
|
}
|
|
}
|
|
|
|
/* We read STOP bits. All of them must be 1 */
|
|
|
|
for (j = fskd->instop; j; j--) {
|
|
r = get_bit_raw(fskd, buffer, len);
|
|
if (r == -1)
|
|
return -1;
|
|
if (!r)
|
|
a |= 0x200;
|
|
}
|
|
|
|
/* And finally we return
|
|
* Bit 8 : Parity error
|
|
* Bit 9 : Framing error
|
|
*/
|
|
|
|
*outbyte = a;
|
|
fskd->state = STATE_SEARCH_STARTBIT;
|
|
return 1;
|
|
}
|