Fri May 26 01:50:38 2006

Asterisk developer's documentation


tdd.h File Reference

TTY/TDD Generation support. More...

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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 zt_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 115 of file tdd.c.

References ecdisa, and tdd_state::pos.

Referenced by zt_setoption().

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 }

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 130 of file tdd.c.

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

Referenced by zt_read().

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 }

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 186 of file tdd.c.

References free.

Referenced by zt_setoption().

00187 {
00188    free(tdd);
00189 }

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)

Definition at line 250 of file tdd.c.

References PUT_TDD.

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 }

void tdd_init void   ) 
 

Initializes the TDD system. Mostly stuff for inverse FFT

Definition at line 81 of file tdd.c.

References TDD_MARK, and TDD_SPACE.

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 }

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 90 of file tdd.c.

References ast_log(), LOG_WARNING, and malloc.

Referenced by zt_setoption().

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 }


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