yafox
/
minimodem-mirror
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Compute expected bit strings outside of main loop

This commit is contained in:
Marcos Vives Del Sol 2014-08-15 18:26:21 +02:00 committed by Kamal Mostafa
parent 163af2539c
commit bbf121a63f
1 changed files with 69 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

115
src/minimodem.c
View File

@ -360,6 +360,52 @@ usage()
exit(1);
}
int
build_expect_bit_string(char * expect_bits_string,
int bfsk_nstartbits,
int bfsk_n_data_bits,
float bfsk_nstopbits,
int invert_start_stop,
unsigned long long bfsk_sync_byte)
{
// example expect_bits_string
// 0123456789A
// isddddddddp i == idle bit (a.k.a. prev_stop bit)
// s == start bit d == data bits p == stop bit
// ebs = "10dddddddd1" <-- expected mark/space framing pattern
//
// NOTE! expect_n_bits ends up being (frame_n_bits+1), because
// we expect the prev_stop bit in addition to this frame's own
// (start + n_data_bits + stop) bits. But for each decoded frame,
// we will advance just frame_n_bits worth of samples, leaving us
// pointing at our stop bit -- it becomes the next frame's prev_stop.
//
// prev_stop--v
// start--v v--stop
// char *expect_bits_string = "10dddddddd1";
//
char start_bit_value = invert_start_stop ? '1' : '0';
char stop_bit_value = invert_start_stop ? '0' : '1';
int j = 0;
if ( bfsk_nstopbits != 0.0 )
expect_bits_string[j++] = stop_bit_value;
int i;
// Nb. only integer number of start bits works (for rx)
for ( i=0; i<bfsk_nstartbits; i++ )
expect_bits_string[j++] = start_bit_value;
for ( i=0; i<bfsk_n_data_bits; i++,j++ ) {
if ( (long long) bfsk_sync_byte >= 0 )
expect_bits_string[j] = ( (bfsk_sync_byte>>i)&1 ) + '0';
else
expect_bits_string[j] = 'd';
}
if ( bfsk_nstopbits != 0.0 )
expect_bits_string[j++] = stop_bit_value;
expect_bits_string[j] = 0;
return j;
}
int
main( int argc, char*argv[] )
{
@ -375,8 +421,11 @@ main( int argc, char*argv[] )
float bfsk_nstopbits = -1;
unsigned int bfsk_do_rx_sync = 0;
unsigned int bfsk_do_tx_sync_bytes = 0;
unsigned int bfsk_sync_byte = -1;
unsigned long long bfsk_sync_byte = -1;
unsigned int bfsk_n_data_bits = 0;
char *expect_data_string = NULL;
char *expect_sync_string = NULL;
unsigned int expect_n_bits;
int invert_start_stop = 0;
int autodetect_shift;
char *filename = NULL;
@ -795,7 +844,6 @@ main( int argc, char*argv[] )
return 0;
}
/*
* Open the input audio stream
*/
@ -898,6 +946,23 @@ main( int argc, char*argv[] )
float frame_n_bits = bfsk_n_data_bits + bfsk_nstartbits + bfsk_nstopbits;
unsigned int frame_nsamples = nsamples_per_bit * frame_n_bits + 0.5;
char expect_data_string_buffer[64];
if (expect_data_string == NULL) {
expect_data_string = expect_data_string_buffer;
expect_n_bits = build_expect_bit_string(expect_data_string, bfsk_nstartbits, bfsk_n_data_bits, bfsk_nstopbits, invert_start_stop, (unsigned long long) -1);
}
fprintf(stderr, "eds = '%s' (%lu)\n", expect_data_string, strlen(expect_data_string));
char expect_sync_string_buffer[64];
if (expect_sync_string == NULL && bfsk_do_rx_sync && (long long) bfsk_sync_byte >= 0) {
expect_sync_string = expect_sync_string_buffer;
build_expect_bit_string(expect_sync_string, bfsk_nstartbits, bfsk_n_data_bits, bfsk_nstopbits, invert_start_stop, bfsk_sync_byte);
} else {
expect_sync_string = expect_data_string;
}
fprintf(stderr, "ess = '%s' (%lu)\n", expect_sync_string, strlen(expect_sync_string));
unsigned int expect_nsamples = nsamples_per_bit * expect_n_bits;
float track_amplitude = 0.0;
float peak_confidence = 0.0;
@ -995,48 +1060,6 @@ main( int argc, char*argv[] )
debug_log( "--------------------------\n");
// example expect_bits_string
// 0123456789A
// isddddddddp i == idle bit (a.k.a. prev_stop bit)
// s == start bit d == data bits p == stop bit
// ebs = "10dddddddd1" <-- expected mark/space framing pattern
//
// NOTE! expect_n_bits ends up being (frame_n_bits+1), because
// we expect the prev_stop bit in addition to this frame's own
// (start + n_data_bits + stop) bits. But for each decoded frame,
// we will advance just frame_n_bits worth of samples, leaving us
// pointing at our stop bit -- it becomes the next frame's prev_stop.
//
// prev_stop--v
// start--v v--stop
// char *expect_bits_string = "10dddddddd1";
//
char expect_bits_string[64];
char start_bit_value = invert_start_stop ? '1' : '0';
char stop_bit_value = invert_start_stop ? '0' : '1';
int j = 0;
if ( bfsk_nstopbits != 0.0 )
expect_bits_string[j++] = stop_bit_value;
int i;
// Nb. only integer number of start bits works (for rx)
for ( i=0; i<bfsk_nstartbits; i++ )
expect_bits_string[j++] = start_bit_value;
for ( i=0; i<bfsk_n_data_bits; i++,j++ ) {
if ( ! carrier && bfsk_do_rx_sync )
expect_bits_string[j] = ( (bfsk_sync_byte>>i)&1 ) + '0';
else
expect_bits_string[j] = 'd';
}
if ( bfsk_nstopbits != 0.0 )
expect_bits_string[j++] = stop_bit_value;
expect_bits_string[j++] = 0;
unsigned int expect_n_bits = strlen(expect_bits_string);
unsigned int expect_nsamples = nsamples_per_bit * expect_n_bits;
// fprintf(stderr, "ebs = '%s' (%lu) ; expect_nsamples=%u samples_nvalid=%lu\n", expect_bits_string, strlen(expect_bits_string), expect_nsamples, samples_nvalid);
if ( samples_nvalid < expect_nsamples )
break;
@ -1078,7 +1101,7 @@ main( int argc, char*argv[] )
try_max_nsamples,
try_step_nsamples,
try_confidence_search_limit,
expect_bits_string,
carrier ? expect_data_string : expect_sync_string,
&bits,
&amplitude,
&frame_start_sample
@ -1186,7 +1209,7 @@ main( int argc, char*argv[] )
try_max_nsamples,
try_step_nsamples,
try_confidence_search_limit,
expect_bits_string,
carrier ? expect_data_string : expect_sync_string,
&bits2,
&amplitude2,
&frame_start_sample2