Sat Aug 6 00:40:06 2011

Asterisk developer's documentation


tdd.h File Reference

TTY/TDD Generation support. More...

Go to the source code of this file.

Defines

#define TDD_BYTES_PER_CHAR   2700

Typedefs

typedef tdd_state TDDSTATE

Functions

int ast_tdd_gen_ecdisa (unsigned char *outbuf, int len)
int tdd_feed (struct tdd_state *tdd, unsigned char *ubuf, int samples)
void tdd_free (struct tdd_state *tdd)
int tdd_generate (struct tdd_state *tdd, unsigned char *buf, const char *string)
void tdd_init (void)
tdd_statetdd_new (void)


Detailed Description

TTY/TDD Generation support.

Note:
Includes code and algorithms from the Zapata library.

Definition in file tdd.h.


Define Documentation

#define TDD_BYTES_PER_CHAR   2700

Definition at line 27 of file tdd.h.

Referenced by dahdi_sendtext().


Typedef Documentation

typedef struct tdd_state TDDSTATE

Definition at line 30 of file tdd.h.


Function Documentation

int ast_tdd_gen_ecdisa ( unsigned char *  outbuf,
int  len 
)

Parameters:
outbuf This is the buffer to receive the tone data
len This is the length (in samples) of the tone data to generate Returns 0 if no error, and -1 if error.

Definition at line 127 of file tdd.c.

References ecdisa, and tdd_state::pos.

Referenced by dahdi_setoption().

00128 {
00129    int pos = 0;
00130    int cnt;
00131    while (len) {
00132       cnt = len > sizeof(ecdisa) ? sizeof(ecdisa) : len;
00133       memcpy(outbuf + pos, ecdisa, cnt);
00134       pos += cnt;
00135       len -= cnt;
00136    }
00137    return 0;
00138 }

int tdd_feed ( struct tdd_state tdd,
unsigned char *  ubuf,
int  samples 
)

Parameters:
tdd Which state machine to act upon
ubuf containing your samples
samples number of samples contained within the buffer.
Send received audio to the TDD demodulator. Returns -1 on error, 0 for "needs more samples", and > 0 (the character) if reception of a character is complete.

Definition at line 140 of file tdd.c.

References ast_log(), AST_MULAW, calloc, free, fsk_serie(), tdd_state::fskd, LOG_ERROR, LOG_NOTICE, LOG_WARNING, tdd_state::mode, tdd_state::oldlen, tdd_state::oldstuff, and tdd_decode_baudot().

00141 {
00142    int mylen = len;
00143    int olen;
00144    int b = 'X';
00145    int res;
00146    int c,x;
00147    short *buf = calloc(1, 2 * len + tdd->oldlen);
00148    short *obuf = buf;
00149    if (!buf) {
00150       ast_log(LOG_WARNING, "Out of memory\n");
00151       return -1;
00152    }
00153    memcpy(buf, tdd->oldstuff, tdd->oldlen);
00154    mylen += tdd->oldlen/2;
00155    for (x = 0; x < len; x++) 
00156       buf[x + tdd->oldlen / 2] = AST_MULAW(ubuf[x]);
00157    c = res = 0;
00158    while (mylen >= 1320) { /* has to have enough to work on */
00159       olen = mylen;
00160       res = fsk_serie(&tdd->fskd, buf, &mylen, &b);
00161       if (mylen < 0) {
00162          ast_log(LOG_ERROR, "fsk_serial made mylen < 0 (%d) (olen was %d)\n", mylen, olen);
00163          free(obuf);
00164          return -1;
00165       }
00166       buf += (olen - mylen);
00167       if (res < 0) {
00168          ast_log(LOG_NOTICE, "fsk_serial failed\n");
00169          free(obuf);
00170          return -1;
00171       }
00172       if (res == 1) {
00173          /* Ignore invalid bytes */
00174          if (b > 0x7f)
00175             continue;
00176          c = tdd_decode_baudot(tdd,b);
00177          if ((c < 1) || (c > 126))
00178             continue; /* if not valid */
00179          break;
00180       }
00181    }
00182    if (mylen) {
00183       memcpy(tdd->oldstuff, buf, mylen * 2);
00184       tdd->oldlen = mylen * 2;
00185    } else
00186       tdd->oldlen = 0;
00187    free(obuf);
00188    if (res) {
00189       tdd->mode = 2; 
00190 /* put it in mode where it
00191          reliably puts teleprinter in correct shift mode */
00192       return(c);
00193    }
00194    return 0;
00195 }

void tdd_free ( struct tdd_state tdd  ) 

Parameters:
tdd This is the tdd_state state machine to free This function frees tdd_state tdd.

Definition at line 197 of file tdd.c.

References free.

Referenced by dahdi_setoption().

00198 {
00199    free(tdd);
00200 }

int tdd_generate ( struct tdd_state tdd,
unsigned char *  buf,
const char *  string 
)

Parameters:
tdd tdd structure
buf Buffer to use. This needs to be large enough to accomodate all the generated samples.
string This is the string to send. This function creates a stream of TDD data in ulaw format. It returns the size (in bytes) of the data (if it returns a size of 0, there is probably an error)

Baudot letters

Baudot figures

Definition at line 261 of file tdd.c.

References tdd_state::charnum, tdd_state::mode, and PUT_TDD.

Referenced by dahdi_sendtext().

00262 {
00263    int bytes=0;
00264    int i,x;
00265    char  c;
00266    /*! Baudot letters */
00267    static unsigned char lstr[31] = "\000E\nA SIU\rDRJNFCKTZLWHYPQOBG\000MXV";
00268    /*! Baudot figures */
00269    static unsigned char fstr[31] = "\0003\n- \00787\r$4',!:(5\")2\0006019?+\000./;";
00270    /* Initial carriers (real/imaginary) */
00271    float cr = 1.0;
00272    float ci = 0.0;
00273    float scont = 0.0;
00274 
00275    for(x = 0; str[x]; x++) {
00276       /* Do synch for each 72th character */
00277       if ( (tdd->charnum++) % 72 == 0) 
00278          PUT_TDD(tdd->mode ? 27 /* FIGS */ : 31 /* LTRS */);
00279 
00280       c = toupper(str[x]);
00281 #if   0
00282       printf("%c",c); fflush(stdout);
00283 #endif
00284       if (c == 0) { /* send null */
00285          PUT_TDD(0);
00286          continue;
00287       }
00288       if (c == '\r') { /* send c/r */
00289          PUT_TDD(8);
00290          continue;
00291       }
00292       if (c == '\n') { /* send c/r and l/f */
00293          PUT_TDD(8);
00294          PUT_TDD(2);
00295          continue;
00296       }
00297       if (c == ' ') { /* send space */
00298          PUT_TDD(4);
00299          continue;
00300       }
00301       for (i = 0; i < 31; i++) {
00302          if (lstr[i] == c)
00303             break;
00304       }
00305       if (i < 31) {        /* if we found it */
00306          if (tdd->mode) { /* if in figs mode, change it */
00307             PUT_TDD(31); /* Send LTRS */
00308             tdd->mode = 0;
00309          }
00310          PUT_TDD(i);
00311          continue;
00312       }
00313       for (i = 0; i < 31; i++) {
00314          if (fstr[i] == c)
00315             break;
00316       }
00317       if (i < 31) {             /* if we found it */
00318          if (tdd->mode != 1) { /* if in ltrs mode, change it */
00319             PUT_TDD(27);      /* send FIGS */
00320             tdd->mode = 1;
00321          }
00322          PUT_TDD(i);           /* send byte */
00323          continue;
00324       }
00325    }
00326    return bytes;
00327 }

void tdd_init ( void   ) 

Initializes the TDD system. Mostly stuff for inverse FFT

Definition at line 93 of file tdd.c.

References TDD_MARK, and TDD_SPACE.

Referenced by main().

00094 {
00095    /* Initialize stuff for inverse FFT */
00096    dr[0] = cos(TDD_SPACE * 2.0 * M_PI / 8000.0);
00097    di[0] = sin(TDD_SPACE * 2.0 * M_PI / 8000.0);
00098    dr[1] = cos(TDD_MARK * 2.0 * M_PI / 8000.0);
00099    di[1] = sin(TDD_MARK * 2.0 * M_PI / 8000.0);
00100 }

struct tdd_state* tdd_new ( void   ) 

This function returns a malloc'd instance of the tdd_state data structure. Returns a pointer to a malloc'd tdd_state structure, or NULL on error.

Definition at line 102 of file tdd.c.

References ast_log(), calloc, and LOG_WARNING.

Referenced by dahdi_setoption().

00103 {
00104    struct tdd_state *tdd;
00105    tdd = calloc(1, sizeof(*tdd));
00106    if (tdd) {
00107       tdd->fskd.spb = 176;        /* 45.5 baud */
00108       tdd->fskd.hdlc = 0;         /* Async */
00109       tdd->fskd.nbit = 5;         /* 5 bits */
00110       tdd->fskd.nstop = 1.5;      /* 1.5 stop bits */
00111       tdd->fskd.paridad = 0;      /* No parity */
00112       tdd->fskd.bw=0;             /* Filter 75 Hz */
00113       tdd->fskd.f_mark_idx = 0;   /* 1400 Hz */
00114       tdd->fskd.f_space_idx = 1;  /* 1800 Hz */
00115       tdd->fskd.pcola = 0;        /* No clue */
00116       tdd->fskd.cont = 0;         /* Digital PLL reset */
00117       tdd->fskd.x0 = 0.0;
00118       tdd->fskd.state = 0;
00119       tdd->pos = 0;
00120       tdd->mode = 0;
00121       tdd->charnum = 0;
00122    } else
00123       ast_log(LOG_WARNING, "Out of memory\n");
00124    return tdd;
00125 }


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