ref: 65875a6263ba836452ec8a658903525ecdfa12ee
dir: /src/cvsd.c/
/*
* CVSD (Continuously Variable Slope Delta modulation)
* conversion routines
*
* The CVSD format is described in the MIL Std 188 113, which is
* available from http://bbs.itsi.disa.mil:5580/T3564
*
* Copyright (C) 1996
* Thomas Sailer (sailer@ife.ee.ethz.ch) (HB9JNX/AE4WA)
* Swiss Federal Institute of Technology, Electronics Lab
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Change History:
*
* June 1, 1998 - Chris Bagwell (cbagwell@sprynet.com)
* Fixed compile warnings reported by Kjetil Torgrim Homme
* <kjetilho@ifi.uio.no>
*
*
*/
/* ---------------------------------------------------------------------- */
#include "st_i.h"
#include <math.h>
#include <string.h>
#include <time.h>
#include <stdio.h>
#include <errno.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h> /* For SEEK_* defines if not found in stdio */
#endif
#include "cvsdfilt.h"
/* ---------------------------------------------------------------------- */
/*
* private data structures
*/
struct cvsd_common_state {
unsigned overload;
float mla_int;
float mla_tc0;
float mla_tc1;
unsigned phase;
unsigned phase_inc;
float v_min, v_max;
};
struct cvsd_decode_state {
float output_filter[DEC_FILTERLEN];
};
struct cvsd_encode_state {
float recon_int;
float input_filter[ENC_FILTERLEN];
};
struct cvsdpriv {
struct cvsd_common_state com;
union {
struct cvsd_decode_state dec;
struct cvsd_encode_state enc;
} c;
struct {
unsigned char shreg;
unsigned mask;
unsigned cnt;
} bit;
unsigned bytes_written;
unsigned cvsd_rate;
};
static int debug_count = 0;
/* ---------------------------------------------------------------------- */
static float float_conv(float *fp1, float *fp2,int n)
{
float res = 0;
for(; n > 0; n--)
res += (*fp1++) * (*fp2++);
return res;
}
/* ---------------------------------------------------------------------- */
/*
* some remarks about the implementation of the CVSD decoder
* the principal integrator is integrated into the output filter
* to achieve this, the coefficients of the output filter are multiplied
* with (1/(1-1/z)) in the initialisation code.
* the output filter must have a sharp zero at f=0 (i.e. the sum of the
* filter parameters must be zero). This prevents an accumulation of
* DC voltage at the principal integration.
*/
/* ---------------------------------------------------------------------- */
static void cvsdstartcommon(ft_t ft)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
p->cvsd_rate = (ft->signal.rate <= 24000) ? 16000 : 32000;
ft->signal.rate = 8000;
ft->signal.channels = 1;
ft->signal.size = ST_SIZE_16BIT; /* make output format default to words */
ft->signal.encoding = ST_ENCODING_SIGN2;
/*
* initialize the decoder
*/
p->com.overload = 0x5;
p->com.mla_int = 0;
/*
* timeconst = (1/e)^(200 / SR) = exp(-200/SR)
* SR is the sampling rate
*/
p->com.mla_tc0 = exp((-200.0)/((float)(p->cvsd_rate)));
/*
* phase_inc = 32000 / SR
*/
p->com.phase_inc = 32000 / p->cvsd_rate;
/*
* initialize bit shift register
*/
p->bit.shreg = p->bit.cnt = 0;
p->bit.mask = 1;
/*
* count the bytes written
*/
p->bytes_written = 0;
p->com.v_min = 1;
p->com.v_max = -1;
st_report("cvsd: bit rate %dbit/s, bits from %s", p->cvsd_rate,
ft->signal.reverse_bits ? "msb to lsb" : "lsb to msb");
}
/* ---------------------------------------------------------------------- */
static int st_cvsdstartread(ft_t ft)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
float *fp1;
int i;
cvsdstartcommon(ft);
p->com.mla_tc1 = 0.1 * (1 - p->com.mla_tc0);
p->com.phase = 0;
/*
* initialize the output filter coeffs (i.e. multiply
* the coeffs with (1/(1-1/z)) to achieve integration
* this is now done in the filter parameter generation utility
*/
/*
* zero the filter
*/
for(fp1 = p->c.dec.output_filter, i = DEC_FILTERLEN; i > 0; i--)
*fp1++ = 0;
return (ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static int st_cvsdstartwrite(ft_t ft)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
float *fp1;
int i;
cvsdstartcommon(ft);
p->com.mla_tc1 = 0.1 * (1 - p->com.mla_tc0);
p->com.phase = 4;
/*
* zero the filter
*/
for(fp1 = p->c.enc.input_filter, i = ENC_FILTERLEN; i > 0; i--)
*fp1++ = 0;
p->c.enc.recon_int = 0;
return(ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static int st_cvsdstopwrite(ft_t ft)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
if (p->bit.cnt) {
st_writeb(ft, p->bit.shreg);
p->bytes_written++;
}
st_debug("cvsd: min slope %f, max slope %f",
p->com.v_min, p->com.v_max);
return (ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static int st_cvsdstopread(ft_t ft)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
st_debug("cvsd: min value %f, max value %f",
p->com.v_min, p->com.v_max);
return(ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static st_size_t st_cvsdread(ft_t ft, st_sample_t *buf, st_size_t nsamp)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
st_size_t done = 0;
float oval;
while (done < nsamp) {
if (!p->bit.cnt) {
if (st_readb(ft, &(p->bit.shreg)) == ST_EOF)
return done;
p->bit.cnt = 8;
p->bit.mask = 1;
}
/*
* handle one bit
*/
p->bit.cnt--;
p->com.overload = ((p->com.overload << 1) |
(!!(p->bit.shreg & p->bit.mask))) & 7;
p->bit.mask <<= 1;
p->com.mla_int *= p->com.mla_tc0;
if ((p->com.overload == 0) || (p->com.overload == 7))
p->com.mla_int += p->com.mla_tc1;
memmove(p->c.dec.output_filter+1, p->c.dec.output_filter,
sizeof(p->c.dec.output_filter)-sizeof(float));
if (p->com.overload & 1)
p->c.dec.output_filter[0] = p->com.mla_int;
else
p->c.dec.output_filter[0] = -p->com.mla_int;
/*
* check if the next output is due
*/
p->com.phase += p->com.phase_inc;
if (p->com.phase >= 4) {
oval = float_conv(p->c.dec.output_filter,
(p->cvsd_rate < 24000) ?
dec_filter_16 : dec_filter_32,
DEC_FILTERLEN);
st_debug_more("input %d %f\n", debug_count, p->com.mla_int);
st_debug_more("recon %d %f\n", debug_count, oval);
debug_count++;
if (oval > p->com.v_max)
p->com.v_max = oval;
if (oval < p->com.v_min)
p->com.v_min = oval;
*buf++ = (oval * ((float)ST_SAMPLE_MAX));
done++;
}
p->com.phase &= 3;
}
return done;
}
/* ---------------------------------------------------------------------- */
static st_size_t st_cvsdwrite(ft_t ft, const st_sample_t *buf, st_size_t nsamp)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
st_size_t done = 0;
float inval;
for(;;) {
/*
* check if the next input is due
*/
if (p->com.phase >= 4) {
if (done >= nsamp)
return done;
memmove(p->c.enc.input_filter+1, p->c.enc.input_filter,
sizeof(p->c.enc.input_filter)-sizeof(float));
p->c.enc.input_filter[0] = (*buf++) /
((float)ST_SAMPLE_MAX);
done++;
}
p->com.phase &= 3;
/* insert input filter here! */
inval = float_conv(p->c.enc.input_filter,
(p->cvsd_rate < 24000) ?
(enc_filter_16[(p->com.phase >= 2)]) :
(enc_filter_32[p->com.phase]),
ENC_FILTERLEN);
/*
* encode one bit
*/
p->com.overload = (((p->com.overload << 1) |
(inval > p->c.enc.recon_int)) & 7);
p->com.mla_int *= p->com.mla_tc0;
if ((p->com.overload == 0) || (p->com.overload == 7))
p->com.mla_int += p->com.mla_tc1;
if (p->com.mla_int > p->com.v_max)
p->com.v_max = p->com.mla_int;
if (p->com.mla_int < p->com.v_min)
p->com.v_min = p->com.mla_int;
if (p->com.overload & 1) {
p->c.enc.recon_int += p->com.mla_int;
p->bit.shreg |= p->bit.mask;
} else
p->c.enc.recon_int -= p->com.mla_int;
if ((++(p->bit.cnt)) >= 8) {
st_writeb(ft, p->bit.shreg);
p->bytes_written++;
p->bit.shreg = p->bit.cnt = 0;
p->bit.mask = 1;
} else
p->bit.mask <<= 1;
p->com.phase += p->com.phase_inc;
st_debug_more("input %d %f\n", debug_count, inval);
st_debug_more("recon %d %f\n", debug_count, p->c.enc.recon_int);
debug_count++;
}
}
/* ---------------------------------------------------------------------- */
/*
* DVMS file header
*/
struct dvms_header {
char Filename[14];
unsigned Id;
unsigned State;
time_t Unixtime;
unsigned Usender;
unsigned Ureceiver;
st_size_t Length;
unsigned Srate;
unsigned Days;
unsigned Custom1;
unsigned Custom2;
char Info[16];
char extend[64];
unsigned Crc;
};
#define DVMS_HEADER_LEN 120
/* ---------------------------------------------------------------------- */
static int dvms_read_header(ft_t ft, struct dvms_header *hdr)
{
unsigned char hdrbuf[DVMS_HEADER_LEN];
unsigned char *pch = hdrbuf;
int i;
unsigned sum;
if (st_readbuf(ft, hdrbuf, sizeof(hdrbuf), 1) != 1)
{
return (ST_EOF);
}
for(i = sizeof(hdrbuf), sum = 0; i > /*2*/3; i--) /* Deti bug */
sum += *pch++;
pch = hdrbuf;
memcpy(hdr->Filename, pch, sizeof(hdr->Filename));
pch += sizeof(hdr->Filename);
hdr->Id = get16_le(&pch);
hdr->State = get16_le(&pch);
hdr->Unixtime = get32_le(&pch);
hdr->Usender = get16_le(&pch);
hdr->Ureceiver = get16_le(&pch);
hdr->Length = get32_le(&pch);
hdr->Srate = get16_le(&pch);
hdr->Days = get16_le(&pch);
hdr->Custom1 = get16_le(&pch);
hdr->Custom2 = get16_le(&pch);
memcpy(hdr->Info, pch, sizeof(hdr->Info));
pch += sizeof(hdr->Info);
memcpy(hdr->extend, pch, sizeof(hdr->extend));
pch += sizeof(hdr->extend);
hdr->Crc = get16_le(&pch);
if (sum != hdr->Crc)
{
st_report("DVMS header checksum error, read %u, calculated %u",
hdr->Crc, sum);
return (ST_EOF);
}
return (ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
/*
* note! file must be seekable
*/
static int dvms_write_header(ft_t ft, struct dvms_header *hdr)
{
unsigned char hdrbuf[DVMS_HEADER_LEN];
unsigned char *pch = hdrbuf;
unsigned char *pchs = hdrbuf;
int i;
unsigned sum;
memcpy(pch, hdr->Filename, sizeof(hdr->Filename));
pch += sizeof(hdr->Filename);
put16_le(&pch, hdr->Id);
put16_le(&pch, hdr->State);
put32_le(&pch, hdr->Unixtime);
put16_le(&pch, hdr->Usender);
put16_le(&pch, hdr->Ureceiver);
put32_le(&pch, hdr->Length);
put16_le(&pch, hdr->Srate);
put16_le(&pch, hdr->Days);
put16_le(&pch, hdr->Custom1);
put16_le(&pch, hdr->Custom2);
memcpy(pch, hdr->Info, sizeof(hdr->Info));
pch += sizeof(hdr->Info);
memcpy(pch, hdr->extend, sizeof(hdr->extend));
pch += sizeof(hdr->extend);
for(i = sizeof(hdrbuf), sum = 0; i > /*2*/3; i--) /* Deti bug */
sum += *pchs++;
hdr->Crc = sum;
put16_le(&pch, hdr->Crc);
if (st_seeki(ft, 0, SEEK_SET) < 0)
{
st_report("seek failed\n: %s",strerror(errno));
return (ST_EOF);
}
if (st_writebuf(ft, hdrbuf, sizeof(hdrbuf), 1) != 1)
{
st_report("%s",strerror(errno));
return (ST_EOF);
}
return (ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static void make_dvms_hdr(ft_t ft, struct dvms_header *hdr)
{
struct cvsdpriv *p = (struct cvsdpriv *) ft->priv;
size_t len;
memset(hdr->Filename, 0, sizeof(hdr->Filename));
len = strlen(ft->filename);
if (len >= sizeof(hdr->Filename))
len = sizeof(hdr->Filename)-1;
memcpy(hdr->Filename, ft->filename, len);
hdr->Id = hdr->State = 0;
hdr->Unixtime = time(NULL);
hdr->Usender = hdr->Ureceiver = 0;
hdr->Length = p->bytes_written;
hdr->Srate = p->cvsd_rate/100;
hdr->Days = hdr->Custom1 = hdr->Custom2 = 0;
memset(hdr->Info, 0, sizeof(hdr->Info));
len = strlen(ft->comment);
if (len >= sizeof(hdr->Info))
len = sizeof(hdr->Info)-1;
memcpy(hdr->Info, ft->comment, len);
memset(hdr->extend, 0, sizeof(hdr->extend));
}
/* ---------------------------------------------------------------------- */
static int st_dvmsstartread(ft_t ft)
{
struct dvms_header hdr;
int rc;
rc = dvms_read_header(ft, &hdr);
if (rc){
st_fail_errno(ft,ST_EHDR,"unable to read DVMS header");
return rc;
}
st_debug("DVMS header of source file \"%s\":");
st_debug(" filename \"%.14s\"",ft->filename);
st_debug(" id 0x%x", hdr.Filename);
st_debug(" state 0x%x", hdr.Id, hdr.State);
st_debug(" time %s",ctime(&hdr.Unixtime)); /* ctime generates lf */
st_debug(" usender %u", hdr.Usender);
st_debug(" ureceiver %u", hdr.Ureceiver);
st_debug(" length %u", hdr.Length);
st_debug(" srate %u", hdr.Srate);
st_debug(" days %u", hdr.Days);
st_debug(" custom1 %u", hdr.Custom1);
st_debug(" custom2 %u", hdr.Custom2);
st_debug(" info \"%.16s\"", hdr.Info);
ft->signal.rate = (hdr.Srate < 240) ? 16000 : 32000;
st_debug("DVMS rate %dbit/s using %dbit/s deviation %d%%",
hdr.Srate*100, ft->signal.rate,
((ft->signal.rate - hdr.Srate*100) * 100) / ft->signal.rate);
rc = st_cvsdstartread(ft);
if (rc)
return rc;
return(ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static int st_dvmsstartwrite(ft_t ft)
{
struct dvms_header hdr;
int rc;
rc = st_cvsdstartwrite(ft);
if (rc)
return rc;
make_dvms_hdr(ft, &hdr);
rc = dvms_write_header(ft, &hdr);
if (rc){
st_fail_errno(ft,rc,"cannot write DVMS header");
return rc;
}
if (!ft->seekable)
st_warn("Length in output .DVMS header will wrong since can't seek to fix it");
return(ST_SUCCESS);
}
/* ---------------------------------------------------------------------- */
static int st_dvmsstopwrite(ft_t ft)
{
struct dvms_header hdr;
int rc;
st_cvsdstopwrite(ft);
if (!ft->seekable)
{
st_warn("File not seekable");
return (ST_EOF);
}
if (st_seeki(ft, 0L, 0) != 0)
{
st_fail_errno(ft,errno,"Can't rewind output file to rewrite DVMS header.");
return(ST_EOF);
}
make_dvms_hdr(ft, &hdr);
rc = dvms_write_header(ft, &hdr);
if(rc){
st_fail_errno(ft,rc,"cannot write DVMS header");
return rc;
}
return rc;
}
/* ---------------------------------------------------------------------- */
/* Cont. Variable Slope Delta */
static const char *cvsdnames[] = {
"cvs",
"cvsd",
NULL
};
static st_format_t st_cvsd_format = {
cvsdnames,
NULL,
0,
st_cvsdstartread,
st_cvsdread,
st_cvsdstopread,
st_cvsdstartwrite,
st_cvsdwrite,
st_cvsdstopwrite,
st_format_nothing_seek
};
const st_format_t *st_cvsd_format_fn(void)
{
return &st_cvsd_format;
}
/* Cont. Variable Solot Delta */
static const char *dvmsnames[] = {
"vms",
"dvms",
NULL
};
static st_format_t st_dvms_format = {
dvmsnames,
NULL,
0,
st_dvmsstartread,
st_cvsdread,
st_cvsdstopread,
st_dvmsstartwrite,
st_cvsdwrite,
st_dvmsstopwrite,
st_format_nothing_seek
};
const st_format_t *st_dvms_format_fn(void)
{
return &st_dvms_format;
}