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minimodem -T rtty (baudot RTTY transmit)

This commit is contained in:
Kamal Mostafa 2011-06-18 21:03:20 -07:00
parent 286879cfb3
commit 2a7f8214df
3 changed files with 248 additions and 20 deletions
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209
src/baudot.c
View File

@ -9,10 +9,19 @@
#include <assert.h> #include <assert.h>
#include <ctype.h>
#include <stdio.h>
//#define BAUDOT_DEBUG
#ifdef BAUDOT_DEBUG
# define debug_log(format, args...) fprintf(stderr, format, ## args)
#else
# define debug_log(format, args...)
#endif
static char static char
baudot_table[32][3] = { baudot_decode_table[32][3] = {
// letter, U.S. figs, CCITT No.2 figs (Europe) // letter, U.S. figs, CCITT No.2 figs (Europe)
{ '*', '*', '*' }, // NUL { '*', '*', '*' }, // NUL
{ 'E', '3', '3' }, { 'E', '3', '3' },
@ -51,18 +60,137 @@ baudot_table[32][3] = {
{ '*', '*', '*' }, // LTRS { '*', '*', '*' }, // LTRS
}; };
static char
baudot_encode_table[0x60][2] = {
// index: ascii char; values: bits, ltrs_or_figs_or_neither_or_both
/* 0x00 */
/* NUL */ { 0x00, 3 }, // NUL
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* BEL */ { 0x05, 2 }, // BELL (or CCITT2 apostrophe)
/* BS */ { 0, 0 }, // non-encodable (FIXME???)
/* xxx */ { 0, 0 }, // non-encodable
/* LF */ { 0x02, 3 }, // LF
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* 0xD */ { 0x08, 3 }, // CR
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* 0x10 */
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* xxx */ { 0, 0 }, // non-encodable
/* 0x20 */
/* */ { 0x04, 3 }, // SPACE
/* ! */ { 0x0d, 2 }, //
/* " */ { 0x11, 2 }, //
/* # */ { 0x14, 2 }, // '#' (or CCITT2 British pounds symbol)
/* $ */ { 0x09, 2 }, // '$' (or CCITT2 ENQ)
/* % */ { 0, 0 }, // non-encodable
/* & */ { 0x1a, 2 }, //
/* ' */ { 0x0b, 2 }, // apostrophe (or CCITT2 BELL)
/* ( */ { 0x0f, 2 }, //
/* ) */ { 0x12, 2 }, //
/* * */ { 0, 0 }, // non-encodable
/* + */ { 0x12, 2 }, //
/* , */ { 0x0c, 2 }, //
/* - */ { 0x03, 2 }, //
/* . */ { 0x1c, 2 }, //
/* / */ { 0x1d, 2 }, //
/* 0x30 */
/* 0 */ { 0x16, 2 }, //
/* 1 */ { 0x17, 2 }, //
/* 2 */ { 0x13, 2 }, //
/* 3 */ { 0x01, 2 }, //
/* 4 */ { 0x0a, 2 }, //
/* 5 */ { 0x10, 2 }, //
/* 6 */ { 0x15, 2 }, //
/* 7 */ { 0x07, 2 }, //
/* 8 */ { 0x06, 2 }, //
/* 9 */ { 0x18, 2 }, //
/* : */ { 0x0e, 2 }, //
/* ; */ { 0x1e, 2 }, //
/* < */ { 0, 0 }, // non-encodable
/* = */ { 0, 0 }, // non-encodable
/* > */ { 0, 0 }, // non-encodable
/* ? */ { 0x19, 2 }, //
/* 0x40 */
/* @ */ { 0, 0 }, // non-encodable
/* A */ { 0x03, 1 }, //
/* B */ { 0x19, 1 }, //
/* C */ { 0x0e, 1 }, //
/* D */ { 0x09, 1 }, //
/* E */ { 0x01, 1 }, //
/* F */ { 0x0d, 1 }, //
/* G */ { 0x1a, 1 }, //
/* H */ { 0x14, 1 }, //
/* I */ { 0x06, 1 }, //
/* J */ { 0x0b, 1 }, //
/* K */ { 0x0f, 1 }, //
/* L */ { 0x12, 1 }, //
/* M */ { 0x1c, 1 }, //
/* N */ { 0x0c, 1 }, //
/* O */ { 0x18, 1 }, //
/* 0x50 */
/* P */ { 0x16, 1 }, //
/* Q */ { 0x17, 1 }, //
/* R */ { 0x0a, 1 }, //
/* S */ { 0x05, 1 }, //
/* T */ { 0x10, 1 }, //
/* U */ { 0x07, 1 }, //
/* V */ { 0x1e, 1 }, //
/* W */ { 0x13, 1 }, //
/* X */ { 0x1d, 1 }, //
/* Y */ { 0x15, 1 }, //
/* Z */ { 0x11, 1 }, //
/* [ */ { 0, 0 }, // non-encodable
/* \\ */ { 0, 0 }, // non-encodable
/* ] */ { 0, 0 }, // non-encodable
/* ^ */ { 0, 0 }, // non-encodable
/* _ */ { 0, 0 }, // non-encodable
};
#define BAUDOT_LTRS 0x1F #define BAUDOT_LTRS 0x1F
#define BAUDOT_FIGS 0x1B #define BAUDOT_FIGS 0x1B
#define BAUDOT_SPACE 0x04 #define BAUDOT_SPACE 0x04
/*
* 0 unknown state
* 1 LTRS state
* 2 FIGS state
*/
static int baudot_charset = 0; // FIXME static int baudot_charset = 0; // FIXME
void void
baudot_reset() baudot_reset()
{ {
baudot_charset = 0; baudot_charset = 1;
} }
@ -79,16 +207,83 @@ baudot_decode( char *char_outp, unsigned char databits )
int stuff_char = 1; int stuff_char = 1;
if ( databits == BAUDOT_FIGS ) { if ( databits == BAUDOT_FIGS ) {
baudot_charset = 1; baudot_charset = 2;
stuff_char = 0; stuff_char = 0;
} else if ( databits == BAUDOT_LTRS ) { } else if ( databits == BAUDOT_LTRS ) {
baudot_charset = 0; baudot_charset = 1;
stuff_char = 0; stuff_char = 0;
} else if ( databits == BAUDOT_SPACE ) { } else if ( databits == BAUDOT_SPACE ) { /* RX un-shift on space */
baudot_charset = 0; baudot_charset = 1;
} }
if ( stuff_char ) if ( stuff_char )
*char_outp = baudot_table[databits][baudot_charset]; *char_outp = baudot_decode_table[databits][baudot_charset-1];
return stuff_char; return stuff_char;
} }
static void
baudot_skip_warning( char char_out )
{
unsigned char byte = char_out;
fprintf(stderr, "W: baudot skipping non-encodable character '%c' 0x%02x\n",
char_out, byte);
}
/*
* Returns the number of 5-bit data words stuffed into *databits_outp (1 or 2)
*/
int
baudot_encode( unsigned int *databits_outp, char char_out )
{
char_out = toupper(char_out);
if( char_out >= 0x60 || char_out < 0 ) {
baudot_skip_warning(char_out);
return 0;
}
unsigned char ind = char_out;
int n = 0;
unsigned char charset_mask = baudot_encode_table[ind][1];
debug_log("I: (baudot_charset==%u) input character '%c' 0x%02x charset_mask=%u\n", baudot_charset, char_out, char_out, charset_mask);
if ( (baudot_charset & charset_mask ) == 0 ) {
if ( charset_mask == 0 ) {
baudot_skip_warning(char_out);
return 0;
}
if ( baudot_charset == 0 )
baudot_charset = 1;
if ( charset_mask != 3 )
baudot_charset = charset_mask;
if ( baudot_charset == 1 )
databits_outp[n++] = BAUDOT_LTRS;
else if ( baudot_charset == 2 )
databits_outp[n++] = BAUDOT_FIGS;
else
assert(0);
debug_log("I: emit charset select 0x%02X\n", databits_outp[n-1]);
}
if ( !( baudot_charset == 1 || baudot_charset == 2 ) ) {
fprintf(stderr, "E: baudot input character failed '%c' 0x%02x\n",
char_out, char_out);
fprintf(stderr, "E: baudot_charset==%u\n", baudot_charset);
assert(0);
}
databits_outp[n++] = baudot_encode_table[ind][0];
/* TX un-shift on space */
if ( char_out == ' ' )
baudot_charset = 1;
return n;
}

11
src/baudot.h
View File

@ -11,9 +11,16 @@
void void
baudot_reset(); baudot_reset();
/* /*
* returns nonzero if *char_outp was stuffed with an output character * Returns 1 if *char_outp was stuffed with an output character
* or 0 if no output character was stuffed (in other words, returns
* the count of characters decoded and stuffed).
*/ */
int int
baudot_decode( char *char_outp, unsigned char databits ); baudot_decode( char *char_outp, unsigned char databits );
/*
* Returns the number of 5-bit datawords stuffed into *databits_outp (1 or 2)
*/
int
baudot_encode( unsigned int *databits_outp, char char_out );

48
src/minimodem.c
View File

@ -21,8 +21,17 @@
/* /*
* ASCII 8-bit data framebits decoder (passthrough) * ASCII 8-bit data framebits decoder/encoder (passthrough)
*/ */
/* returns the number of datawords stuffed into *databits_outp */
int
framebits_encode_ascii8( unsigned int *databits_outp, char char_out )
{
*databits_outp = char_out;
return 1;
}
/* returns nbytes decoded */ /* returns nbytes decoded */
static unsigned int static unsigned int
framebits_decode_ascii8( char *dataout_p, unsigned int dataout_size, framebits_decode_ascii8( char *dataout_p, unsigned int dataout_size,
@ -38,8 +47,11 @@ framebits_decode_ascii8( char *dataout_p, unsigned int dataout_size,
/* /*
* Baudot 5-bit data framebits decoder * Baudot 5-bit data framebits decoder/encoder
*/ */
#define framebits_encode_baudot baudot_encode
/* returns nbytes decoded */ /* returns nbytes decoded */
static unsigned int static unsigned int
framebits_decode_baudot( char *dataout_p, unsigned int dataout_size, framebits_decode_baudot( char *dataout_p, unsigned int dataout_size,
@ -63,7 +75,8 @@ static void fsk_transmit_stdin(
float data_rate, float data_rate,
float bfsk_mark_f, float bfsk_mark_f,
float bfsk_space_f, float bfsk_space_f,
int n_data_bits int n_data_bits,
int (*framebits_encoder)( unsigned int *databits_outp, char char_out )
) )
{ {
size_t sample_rate = simpleaudio_get_rate(sa_out); size_t sample_rate = simpleaudio_get_rate(sa_out);
@ -73,14 +86,23 @@ static void fsk_transmit_stdin(
simpleaudio_tone(sa_out, bfsk_mark_f, sample_rate/2); // 0.5 sec leader simpleaudio_tone(sa_out, bfsk_mark_f, sample_rate/2); // 0.5 sec leader
while ( (c = getchar()) != EOF ) while ( (c = getchar()) != EOF )
{ {
simpleaudio_tone(sa_out, bfsk_space_f, bit_nsamples); // start
int i; // HACK - baudot
for ( i=0; i<n_data_bits; i++ ) { // data unsigned int nwords;
unsigned int bit = ( c >> i ) & 1; unsigned int bits[2];
float tone_freq = bit == 1 ? bfsk_mark_f : bfsk_space_f; nwords = framebits_encoder(bits, c);
simpleaudio_tone(sa_out, tone_freq, bit_nsamples);
unsigned int j;
for ( j=0; j<nwords; j++ ) {
simpleaudio_tone(sa_out, bfsk_space_f, bit_nsamples); // start
int i;
for ( i=0; i<n_data_bits; i++ ) { // data
unsigned int bit = ( bits[j] >> i ) & 1;
float tone_freq = bit == 1 ? bfsk_mark_f : bfsk_space_f;
simpleaudio_tone(sa_out, tone_freq, bit_nsamples);
}
simpleaudio_tone(sa_out, bfsk_mark_f, bit_nsamples); // stop
} }
simpleaudio_tone(sa_out, bfsk_mark_f, bit_nsamples); // stop
} }
simpleaudio_tone(sa_out, bfsk_mark_f, sample_rate/2); // 0.5 sec tail simpleaudio_tone(sa_out, bfsk_mark_f, sample_rate/2); // 0.5 sec tail
@ -113,6 +135,7 @@ main( int argc, char*argv[] )
float bfsk_data_rate; float bfsk_data_rate;
int bfsk_n_data_bits; int bfsk_n_data_bits;
int (*bfsk_framebits_encode)( unsigned int *databits_outp, char char_out );
unsigned int (*bfsk_framebits_decode)( char *dataout_p, unsigned int dataout_size, unsigned int (*bfsk_framebits_decode)( char *dataout_p, unsigned int dataout_size,
unsigned int bits ); unsigned int bits );
@ -121,10 +144,12 @@ main( int argc, char*argv[] )
bfsk_data_rate = 45.45; bfsk_data_rate = 45.45;
bfsk_n_data_bits = 5; bfsk_n_data_bits = 5;
bfsk_framebits_decode = framebits_decode_baudot; bfsk_framebits_decode = framebits_decode_baudot;
bfsk_framebits_encode = framebits_encode_baudot;
} else { } else {
bfsk_data_rate = atof(argv[argi]); bfsk_data_rate = atof(argv[argi]);
bfsk_n_data_bits = 8; bfsk_n_data_bits = 8;
bfsk_framebits_decode = framebits_decode_ascii8; bfsk_framebits_decode = framebits_decode_ascii8;
bfsk_framebits_encode = framebits_encode_ascii8;
} }
argi++; argi++;
@ -171,7 +196,8 @@ main( int argc, char*argv[] )
fsk_transmit_stdin(sa_out, fsk_transmit_stdin(sa_out,
bfsk_data_rate, bfsk_data_rate,
bfsk_mark_f, bfsk_space_f, bfsk_mark_f, bfsk_space_f,
bfsk_n_data_bits bfsk_n_data_bits,
bfsk_framebits_encode
); );
return 0; return 0;
} }