tdd.c

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/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * TTY/TDD Generation support 
 * 
 * Copyright (C) 2001, Linux Support Services, Inc.
 *
 * Mark Spencer <markster@linux-support.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License.
 *
 * Includes code and algorithms from the Zapata library.
 *
 */

#include <time.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <ctype.h>
#include <asterisk/ulaw.h>
#include <asterisk/tdd.h>
#include <asterisk/logger.h>
#include <asterisk/fskmodem.h>
#include "ecdisa.h"


struct tdd_state {
   fsk_data fskd;
   char rawdata[256];
   short oldstuff[4096];
   int oldlen;
   int pos;
   int modo;
   int mode;
};

static float dr[4], di[4];
static float tddsb = 176.0;  /* 45.5 baud */

#define TDD_SPACE 1800.0      /* 1800 hz for "0" */
#define TDD_MARK  1400.0      /* 1400 hz for "1" */

static int tdd_decode_baudot(struct tdd_state *tdd,unsigned char data)  /* covert baudot into ASCII */
{
   static char ltrs[32]={'<','E','\n','A',' ','S','I','U',
            '\n','D','R','J','N','F','C','K',
            'T','Z','L','W','H','Y','P','Q',
            'O','B','G','^','M','X','V','^'};
   static char figs[32]={'<','3','\n','-',' ',',','8','7',
            '\n','$','4','\'',',','·',':','(',
            '5','+',')','2','·','6','0','1',
            '9','7','·','^','.','/','=','^'};
   int d;
   d=0;  /* return 0 if not decodeable */
   switch (data) {
   case 0x1f : tdd->modo=0; break;
   case 0x1b : tdd->modo=1; break;
   default: if (tdd->modo==0) d=ltrs[data]; else d=figs[data]; break;
   }
   return d;
}

void tdd_init(void)
{
   /* Initialize stuff for inverse FFT */
   dr[0] = cos(TDD_SPACE * 2.0 * M_PI / 8000.0);
   di[0] = sin(TDD_SPACE * 2.0 * M_PI / 8000.0);
   dr[1] = cos(TDD_MARK * 2.0 * M_PI / 8000.0);
   di[1] = sin(TDD_MARK * 2.0 * M_PI / 8000.0);
}

struct tdd_state *tdd_new(void)
{
   struct tdd_state *tdd;
   tdd = malloc(sizeof(struct tdd_state));
   memset(tdd, 0, sizeof(struct tdd_state));
   if (tdd) {
      tdd->fskd.spb = 176;    /* 45.5 baud */
      tdd->fskd.hdlc = 0;     /* Async */
      tdd->fskd.nbit = 5;     /* 5 bits */
      tdd->fskd.nstop = 1.5;  /* 1.5 stop bits */
      tdd->fskd.paridad = 0;  /* No parity */
      tdd->fskd.bw=0;         /* Filter 75 Hz */
      tdd->fskd.f_mark_idx =  0; /* 1400 Hz */
      tdd->fskd.f_space_idx = 1; /* 1800 Hz */
      tdd->fskd.pcola = 0;    /* No clue */
      tdd->fskd.cont = 0;        /* Digital PLL reset */
      tdd->fskd.x0 = 0.0;
      tdd->fskd.state = 0;
      tdd->pos = 0;
      tdd->mode = 2;
   } else
      ast_log(LOG_WARNING, "Out of memory\n");
   return tdd;
}

int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len)
{
   int pos = 0;
   int cnt;
   while(len) {
      cnt = len;
      if (cnt > sizeof(ecdisa))
         cnt = sizeof(ecdisa);
      memcpy(outbuf + pos, ecdisa, cnt);
      pos += cnt;
      len -= cnt;
   }
   return 0;
}

int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int len)
{
   int mylen = len;
   int olen;
   int b = 'X';
   int res;
   int c,x;
   short *buf = malloc(2 * len + tdd->oldlen);
   short *obuf = buf;
   if (!buf) {
      ast_log(LOG_WARNING, "Out of memory\n");
      return -1;
   }
   memset(buf, 0, 2 * len + tdd->oldlen);
   memcpy(buf, tdd->oldstuff, tdd->oldlen);
   mylen += tdd->oldlen/2;
   for (x=0;x<len;x++) 
      buf[x+tdd->oldlen/2] = AST_MULAW(ubuf[x]);
   c = res = 0;
   while(mylen >= 1320) { /* has to have enough to work on */
      olen = mylen;
      res = fsk_serie(&tdd->fskd, buf, &mylen, &b);
      if (mylen < 0) {
         ast_log(LOG_ERROR, "fsk_serie made mylen < 0 (%d) (olen was %d)\n", mylen,olen);
         free(obuf);
         return -1;
      }
      buf += (olen - mylen);
      if (res < 0) {
         ast_log(LOG_NOTICE, "fsk_serie failed\n");
         free(obuf);
         return -1;
      }
      if (res == 1) {
         /* Ignore invalid bytes */
         if (b > 0x7f)
            continue;
         c = tdd_decode_baudot(tdd,b);
         if ((c < 1) || (c > 126)) continue; /* if not valid */
         break;
      }
   }
   if (mylen) {
      memcpy(tdd->oldstuff, buf, mylen * 2);
      tdd->oldlen = mylen * 2;
   } else
      tdd->oldlen = 0;
   free(obuf);
   if (res)  {
      tdd->mode = 2; /* put it in mode where it
         reliably puts teleprinter in correct shift mode */
      return(c);
   }
   return 0;
}

void tdd_free(struct tdd_state *tdd)
{
   free(tdd);
}

static inline float tdd_getcarrier(float *cr, float *ci, int bit)
{
   /* Move along.  There's nothing to see here... */
   float t;
   t = *cr * dr[bit] - *ci * di[bit];
   *ci = *cr * di[bit] + *ci * dr[bit];
   *cr = t;
   
   t = 2.0 - (*cr * *cr + *ci * *ci);
   *cr *= t;
   *ci *= t;
   return *cr;
}  

#define PUT_BYTE(a) do { \
   *(buf++) = (a); \
   bytes++; \
} while(0)

#define PUT_AUDIO_SAMPLE(y) do { \
   int index = (short)(rint(8192.0 * (y))); \
   *(buf++) = AST_LIN2MU(index); \
   bytes++; \
} while(0)
   
#define PUT_TDD_MARKMS do { \
   int x; \
   for (x=0;x<8;x++) \
      PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, 1)); \
} while(0)

#define PUT_TDD_BAUD(bit) do { \
   while(scont < tddsb) { \
      PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, bit)); \
      scont += 1.0; \
   } \
   scont -= tddsb; \
} while(0)

#define PUT_TDD_STOP do { \
   while(scont < (tddsb * 1.5)) { \
      PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, 1)); \
      scont += 1.0; \
   } \
   scont -= (tddsb * 1.5); \
} while(0)


#define PUT_TDD(byte) do { \
   int z; \
   unsigned char b = (byte); \
   PUT_TDD_BAUD(0);  /* Start bit */ \
   for (z=0;z<5;z++) { \
      PUT_TDD_BAUD(b & 1); \
      b >>= 1; \
   } \
   PUT_TDD_STOP;  /* Stop bit */ \
} while(0); 

int tdd_generate(struct tdd_state *tdd, unsigned char *buf, char *str)
{
   int bytes=0;
   int i,x;
   char  c;
   static unsigned char lstr[31] = "\000E\nA SIU\rDRJNFCKTZLWHYPQOBG\000MXV";
   static unsigned char fstr[31] = "\0003\n- \00787\r$4',!:(5\")2\0006019?&\000./;";
   /* Initial carriers (real/imaginary) */
   float cr = 1.0;
   float ci = 0.0;
   float scont = 0.0;

   for(x = 0; str[x]; x++) {
      c = toupper(str[x]);
#if   0
      printf("%c",c); fflush(stdout);
#endif
      if (c == 0) /* send null */
         {
         PUT_TDD(0);
         continue;
         }
      if (c == '\r') /* send c/r */
         {
         PUT_TDD(8);
         continue;
         }
      if (c == '\n') /* send c/r and l/f */
         {
         PUT_TDD(8);
         PUT_TDD(2);
         continue;
         }
      if (c == ' ') /* send space */
         {
         PUT_TDD(4);
         continue;
         }
      for(i = 0; i < 31; i++)
         {
         if (lstr[i] == c) break;
         }
      if (i < 31) /* if we found it */
         {
         if (tdd->mode)  /* if in figs mode, change it */
            { 
            PUT_TDD(31); /* Send LTRS */
            tdd->mode = 0;
            }
         PUT_TDD(i);
         continue;
         }
      for(i = 0; i < 31; i++)
         {
         if (fstr[i] == c) break;
         }
      if (i < 31) /* if we found it */
         {
         if (tdd->mode != 1)  /* if in ltrs mode, change it */
            {
            PUT_TDD(27); /* send FIGS */
            tdd->mode = 1;
            }
         PUT_TDD(i);  /* send byte */
         continue;
         }
      }
   return bytes;
}

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