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minimodem: performance: read samples in larger blocks 

For performance, read samples from the simpleaudio backend in larger
blocks when the number of bits per frame ends up being small.
This commit is contained in:
Kamal Mostafa 2012-10-01 21:00:28 -07:00
parent 2af26a4d06
commit 2373364d9a
1 changed files with 23 additions and 22 deletions
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45
src/minimodem.c
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@ -754,14 +754,16 @@ main( int argc, char*argv[] )
* we need 11 data-bits worth of samples, and we will scan through one bits
* worth at a time, hence we need a minimum total input buffer size of 12
* data-bits. */
// FIXME I should be able to reduce this to * 9 for 5-bit data, but
// it SOMETIMES crashes -- probably due to non-integer nsamples_per_bit
// FIXME by passing it down into the fsk code?
// FIXME EXPLAIN +1 goes with extra bit when scanning
size_t samplebuf_size = ceilf(nsamples_per_bit) * (12+1);
samplebuf_size *= 2; // account for the half-buf filling method
#define SAMPLE_BUF_DIVISOR 12
#ifdef SAMPLE_BUF_DIVISOR
// For performance, use a larger samplebuf_size than necessary
if ( samplebuf_size < sample_rate / SAMPLE_BUF_DIVISOR )
samplebuf_size = sample_rate / SAMPLE_BUF_DIVISOR;
#endif
float *samplebuf = malloc(samplebuf_size * sizeof(float));
float *samples_readptr = samplebuf;
size_t read_nsamples = samplebuf_size;
size_t samples_nvalid = 0;
debug_log("samplebuf_size=%zu\n", samplebuf_size);
@ -816,8 +818,6 @@ main( int argc, char*argv[] )
assert( advance <= samplebuf_size );
if ( advance == samplebuf_size ) {
samples_nvalid = 0;
samples_readptr = samplebuf;
read_nsamples = samplebuf_size;
advance = 0;
}
if ( advance ) {
@ -826,24 +826,25 @@ main( int argc, char*argv[] )
memmove(samplebuf, samplebuf+advance,
(samplebuf_size-advance)*sizeof(float));
samples_nvalid -= advance;
samples_readptr = samplebuf + (samplebuf_size-advance);
read_nsamples = advance;
}
/* Read more samples into samplebuf (fill it) */
assert ( read_nsamples > 0 );
assert ( samples_nvalid + read_nsamples <= samplebuf_size );
ssize_t r;
r = simpleaudio_read(sa, samples_readptr, read_nsamples);
debug_log("simpleaudio_read(samplebuf+%zd, n=%zu) returns %zd\n",
samples_readptr - samplebuf, read_nsamples, r);
if ( r < 0 ) {
fprintf(stderr, "simpleaudio_read: error\n");
ret = -1;
break;
}
else if ( r > 0 )
if ( samples_nvalid < samplebuf_size/2 ) {
float *samples_readptr = samplebuf + samples_nvalid;
size_t read_nsamples = samplebuf_size/2;
/* Read more samples into samplebuf (fill it) */
assert ( read_nsamples > 0 );
assert ( samples_nvalid + read_nsamples <= samplebuf_size );
ssize_t r;
r = simpleaudio_read(sa, samples_readptr, read_nsamples);
debug_log("simpleaudio_read(samplebuf+%zd, n=%zu) returns %zd\n",
samples_readptr - samplebuf, read_nsamples, r);
if ( r < 0 ) {
fprintf(stderr, "simpleaudio_read: error\n");
ret = -1;
break;
}
samples_nvalid += r;
}
if ( samples_nvalid == 0 )
break;