Sun Aug 6 15:02:47 2006

Asterisk developer's documentation


Main Page | Modules | Alphabetical List | Data Structures | Directories | File List | Data Fields | Globals | Related Pages

tdd.c

Go to the documentation of this file.
00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * Includes code and algorithms from the Zapata library.
00009  *
00010  * See http://www.asterisk.org for more information about
00011  * the Asterisk project. Please do not directly contact
00012  * any of the maintainers of this project for assistance;
00013  * the project provides a web site, mailing lists and IRC
00014  * channels for your use.
00015  *
00016  * This program is free software, distributed under the terms of
00017  * the GNU General Public License Version 2. See the LICENSE file
00018  * at the top of the source tree.
00019  */
00020 
00021 /*! \file
00022  *
00023  * \brief TTY/TDD Generation support 
00024  * 
00025  */
00026 
00027 #include <time.h>
00028 #include <string.h>
00029 #include <stdio.h>
00030 #include <stdlib.h>
00031 #include <unistd.h>
00032 #include <math.h>
00033 #include <ctype.h>
00034 
00035 #include "asterisk.h"
00036 
00037 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 7221 $")
00038 
00039 #include "asterisk/ulaw.h"
00040 #include "asterisk/tdd.h"
00041 #include "asterisk/logger.h"
00042 #include "asterisk/fskmodem.h"
00043 #include "ecdisa.h"
00044 
00045 struct tdd_state {
00046    fsk_data fskd;
00047    char rawdata[256];
00048    short oldstuff[4096];
00049    int oldlen;
00050    int pos;
00051    int modo;
00052    int mode;
00053 };
00054 
00055 static float dr[4], di[4];
00056 static float tddsb = 176.0;  /* 45.5 baud */
00057 
00058 #define TDD_SPACE 1800.0      /* 1800 hz for "0" */
00059 #define TDD_MARK  1400.0      /* 1400 hz for "1" */
00060 
00061 static int tdd_decode_baudot(struct tdd_state *tdd,unsigned char data)  /* covert baudot into ASCII */
00062 {
00063    static char ltrs[32]={'<','E','\n','A',' ','S','I','U',
00064             '\n','D','R','J','N','F','C','K',
00065             'T','Z','L','W','H','Y','P','Q',
00066             'O','B','G','^','M','X','V','^'};
00067    static char figs[32]={'<','3','\n','-',' ',',','8','7',
00068             '\n','$','4','\'',',','·',':','(',
00069             '5','+',')','2','·','6','0','1',
00070             '9','7','·','^','.','/','=','^'};
00071    int d;
00072    d=0;  /* return 0 if not decodeable */
00073    switch (data) {
00074    case 0x1f : tdd->modo=0; break;
00075    case 0x1b : tdd->modo=1; break;
00076    default: if (tdd->modo==0) d=ltrs[data]; else d=figs[data]; break;
00077    }
00078    return d;
00079 }
00080 
00081 void tdd_init(void)
00082 {
00083    /* Initialize stuff for inverse FFT */
00084    dr[0] = cos(TDD_SPACE * 2.0 * M_PI / 8000.0);
00085    di[0] = sin(TDD_SPACE * 2.0 * M_PI / 8000.0);
00086    dr[1] = cos(TDD_MARK * 2.0 * M_PI / 8000.0);
00087    di[1] = sin(TDD_MARK * 2.0 * M_PI / 8000.0);
00088 }
00089 
00090 struct tdd_state *tdd_new(void)
00091 {
00092    struct tdd_state *tdd;
00093    tdd = malloc(sizeof(struct tdd_state));
00094    if (tdd) {
00095       memset(tdd, 0, sizeof(struct tdd_state));
00096       tdd->fskd.spb = 176;    /* 45.5 baud */
00097       tdd->fskd.hdlc = 0;     /* Async */
00098       tdd->fskd.nbit = 5;     /* 5 bits */
00099       tdd->fskd.nstop = 1.5;  /* 1.5 stop bits */
00100       tdd->fskd.paridad = 0;  /* No parity */
00101       tdd->fskd.bw=0;         /* Filter 75 Hz */
00102       tdd->fskd.f_mark_idx =  0; /* 1400 Hz */
00103       tdd->fskd.f_space_idx = 1; /* 1800 Hz */
00104       tdd->fskd.pcola = 0;    /* No clue */
00105       tdd->fskd.cont = 0;        /* Digital PLL reset */
00106       tdd->fskd.x0 = 0.0;
00107       tdd->fskd.state = 0;
00108       tdd->pos = 0;
00109       tdd->mode = 2;
00110    } else
00111       ast_log(LOG_WARNING, "Out of memory\n");
00112    return tdd;
00113 }
00114 
00115 int ast_tdd_gen_ecdisa(unsigned char *outbuf, int len)
00116 {
00117    int pos = 0;
00118    int cnt;
00119    while(len) {
00120       cnt = len;
00121       if (cnt > sizeof(ecdisa))
00122          cnt = sizeof(ecdisa);
00123       memcpy(outbuf + pos, ecdisa, cnt);
00124       pos += cnt;
00125       len -= cnt;
00126    }
00127    return 0;
00128 }
00129 
00130 int tdd_feed(struct tdd_state *tdd, unsigned char *ubuf, int len)
00131 {
00132    int mylen = len;
00133    int olen;
00134    int b = 'X';
00135    int res;
00136    int c,x;
00137    short *buf = malloc(2 * len + tdd->oldlen);
00138    short *obuf = buf;
00139    if (!buf) {
00140       ast_log(LOG_WARNING, "Out of memory\n");
00141       return -1;
00142    }
00143    memset(buf, 0, 2 * len + tdd->oldlen);
00144    memcpy(buf, tdd->oldstuff, tdd->oldlen);
00145    mylen += tdd->oldlen/2;
00146    for (x=0;x<len;x++) 
00147       buf[x+tdd->oldlen/2] = AST_MULAW(ubuf[x]);
00148    c = res = 0;
00149    while(mylen >= 1320) { /* has to have enough to work on */
00150       olen = mylen;
00151       res = fsk_serie(&tdd->fskd, buf, &mylen, &b);
00152       if (mylen < 0) {
00153          ast_log(LOG_ERROR, "fsk_serie made mylen < 0 (%d) (olen was %d)\n", mylen,olen);
00154          free(obuf);
00155          return -1;
00156       }
00157       buf += (olen - mylen);
00158       if (res < 0) {
00159          ast_log(LOG_NOTICE, "fsk_serie failed\n");
00160          free(obuf);
00161          return -1;
00162       }
00163       if (res == 1) {
00164          /* Ignore invalid bytes */
00165          if (b > 0x7f)
00166             continue;
00167          c = tdd_decode_baudot(tdd,b);
00168          if ((c < 1) || (c > 126)) continue; /* if not valid */
00169          break;
00170       }
00171    }
00172    if (mylen) {
00173       memcpy(tdd->oldstuff, buf, mylen * 2);
00174       tdd->oldlen = mylen * 2;
00175    } else
00176       tdd->oldlen = 0;
00177    free(obuf);
00178    if (res)  {
00179       tdd->mode = 2; /* put it in mode where it
00180          reliably puts teleprinter in correct shift mode */
00181       return(c);
00182    }
00183    return 0;
00184 }
00185 
00186 void tdd_free(struct tdd_state *tdd)
00187 {
00188    free(tdd);
00189 }
00190 
00191 static inline float tdd_getcarrier(float *cr, float *ci, int bit)
00192 {
00193    /* Move along.  There's nothing to see here... */
00194    float t;
00195    t = *cr * dr[bit] - *ci * di[bit];
00196    *ci = *cr * di[bit] + *ci * dr[bit];
00197    *cr = t;
00198    
00199    t = 2.0 - (*cr * *cr + *ci * *ci);
00200    *cr *= t;
00201    *ci *= t;
00202    return *cr;
00203 }  
00204 
00205 #define PUT_BYTE(a) do { \
00206    *(buf++) = (a); \
00207    bytes++; \
00208 } while(0)
00209 
00210 #define PUT_AUDIO_SAMPLE(y) do { \
00211    int index = (short)(rint(8192.0 * (y))); \
00212    *(buf++) = AST_LIN2MU(index); \
00213    bytes++; \
00214 } while(0)
00215    
00216 #define PUT_TDD_MARKMS do { \
00217    int x; \
00218    for (x=0;x<8;x++) \
00219       PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, 1)); \
00220 } while(0)
00221 
00222 #define PUT_TDD_BAUD(bit) do { \
00223    while(scont < tddsb) { \
00224       PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, bit)); \
00225       scont += 1.0; \
00226    } \
00227    scont -= tddsb; \
00228 } while(0)
00229 
00230 #define PUT_TDD_STOP do { \
00231    while(scont < (tddsb * 1.5)) { \
00232       PUT_AUDIO_SAMPLE(tdd_getcarrier(&cr, &ci, 1)); \
00233       scont += 1.0; \
00234    } \
00235    scont -= (tddsb * 1.5); \
00236 } while(0)
00237 
00238 
00239 #define PUT_TDD(byte) do { \
00240    int z; \
00241    unsigned char b = (byte); \
00242    PUT_TDD_BAUD(0);  /* Start bit */ \
00243    for (z=0;z<5;z++) { \
00244       PUT_TDD_BAUD(b & 1); \
00245       b >>= 1; \
00246    } \
00247    PUT_TDD_STOP;  /* Stop bit */ \
00248 } while(0); 
00249 
00250 int tdd_generate(struct tdd_state *tdd, unsigned char *buf, const char *str)
00251 {
00252    int bytes=0;
00253    int i,x;
00254    char  c;
00255    static unsigned char lstr[31] = "\000E\nA SIU\rDRJNFCKTZLWHYPQOBG\000MXV";
00256    static unsigned char fstr[31] = "\0003\n- \00787\r$4',!:(5\")2\0006019?&\000./;";
00257    /* Initial carriers (real/imaginary) */
00258    float cr = 1.0;
00259    float ci = 0.0;
00260    float scont = 0.0;
00261 
00262    for(x = 0; str[x]; x++) {
00263       c = toupper(str[x]);
00264 #if   0
00265       printf("%c",c); fflush(stdout);
00266 #endif
00267       if (c == 0) /* send null */
00268          {
00269          PUT_TDD(0);
00270          continue;
00271          }
00272       if (c == '\r') /* send c/r */
00273          {
00274          PUT_TDD(8);
00275          continue;
00276          }
00277       if (c == '\n') /* send c/r and l/f */
00278          {
00279          PUT_TDD(8);
00280          PUT_TDD(2);
00281          continue;
00282          }
00283       if (c == ' ') /* send space */
00284          {
00285          PUT_TDD(4);
00286          continue;
00287          }
00288       for(i = 0; i < 31; i++)
00289          {
00290          if (lstr[i] == c) break;
00291          }
00292       if (i < 31) /* if we found it */
00293          {
00294          if (tdd->mode)  /* if in figs mode, change it */
00295             { 
00296             PUT_TDD(31); /* Send LTRS */
00297             tdd->mode = 0;
00298             }
00299          PUT_TDD(i);
00300          continue;
00301          }
00302       for(i = 0; i < 31; i++)
00303          {
00304          if (fstr[i] == c) break;
00305          }
00306       if (i < 31) /* if we found it */
00307          {
00308          if (tdd->mode != 1)  /* if in ltrs mode, change it */
00309             {
00310             PUT_TDD(27); /* send FIGS */
00311             tdd->mode = 1;
00312             }
00313          PUT_TDD(i);  /* send byte */
00314          continue;
00315          }
00316       }
00317    return bytes;
00318 }
00319 
00320 

Generated on Sun Aug 6 15:02:47 2006 for Asterisk - the Open Source PBX by  doxygen 1.4.2