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rtl_sdr_fm: add batched consumer API

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This commit is contained in:
arancormonk
2025-09-03 15:51:45 -04:00
parent 30766b34bd
commit 7dd9cd7566
1 changed files with 65 additions and 14 deletions
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79
src/rtl_sdr_fm.cpp
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@@ -279,6 +279,43 @@ static int ring_read_one(struct output_state *o, int16_t *out)
return 0;
}
/* Read up to max_count samples into out. Blocks until at least one sample is available or exit. Returns
number of samples read (>=1) or -1 on exit. Signals producer space once after the batch. */
static int ring_read_batch(struct output_state *o, int16_t *out, size_t max_count)
{
if (max_count == 0) return 0;
while (ring_is_empty(o)) {
struct timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
ts.tv_nsec += 10L * 1000000L; /* 10ms */
if (ts.tv_nsec >= 1000000000L) {
ts.tv_sec += ts.tv_nsec / 1000000000L;
ts.tv_nsec = ts.tv_nsec % 1000000000L;
}
pthread_mutex_lock(&o->ready_m);
pthread_cond_timedwait(&o->ready, &o->ready_m, &ts);
pthread_mutex_unlock(&o->ready_m);
if (exitflag) return -1;
}
size_t available = ring_used(o);
size_t read_now = (max_count < available) ? max_count : available;
size_t t = o->tail.load();
size_t first = o->capacity - t;
if (first > read_now) first = read_now;
memcpy(out, o->buffer + t, first * sizeof(int16_t));
t += first;
if (t == o->capacity) t = 0;
if (read_now > first) {
memcpy(out + first, o->buffer, (read_now - first) * sizeof(int16_t));
t = read_now - first;
}
o->tail.store(t);
/* Signal space available once for the whole batch */
safe_cond_signal(&o->space, &o->ready_m);
return (int)read_now;
}
/* {length, coef, coef, coef} and scaled by 2^15
for now, only length 9, optimal way to get +85% bandwidth */
#define CIC_TABLE_MAX 10
@@ -1409,6 +1446,31 @@ void cleanup_rtlsdr_stream()
rtlsdr_close(dongle.dev);
}
/* Batched consumer API: read up to count samples with fewer wakeups/locks.
Returns number of samples read (>=1) or -1 on exit. Applies volume scaling. */
int get_rtlsdr_samples(int16_t *out, size_t count, dsd_opts * opts, dsd_state * state)
{
UNUSED(state);
if (count == 0) return 0;
/* If PPM Error is Manually Changed, change it here once per batch */
if (opts->rtlsdr_ppm_error != dongle.ppm_error)
{
dongle.ppm_error = opts->rtlsdr_ppm_error;
verbose_ppm_set(dongle.dev, dongle.ppm_error);
}
int got = ring_read_batch(&output, out, count);
if (got <= 0) {
return -1;
}
/* Apply volume scaling */
for (int i = 0; i < got; i++) {
out[i] = out[i] * volume_multiplier;
}
return got;
}
//original for safe keeping
// void get_rtlsdr_sample(int16_t *sample, dsd_opts * opts, dsd_state * state)
// {
@@ -1425,20 +1487,9 @@ void cleanup_rtlsdr_stream()
//find way to modify this function to allow hopping (tuning) while squelched and send 0 sample?
int get_rtlsdr_sample(int16_t *sample, dsd_opts * opts, dsd_state * state)
{
UNUSED(state);
//if PPM Error is Manually Changed, Change it here now
if (opts->rtlsdr_ppm_error != dongle.ppm_error)
{
dongle.ppm_error = opts->rtlsdr_ppm_error;
verbose_ppm_set(dongle.dev, dongle.ppm_error);
}
int16_t tmp;
if (ring_read_one(&output, &tmp) < 0) {
return -1;
}
*sample = tmp * volume_multiplier;
/* Delegate to batched API for a single sample */
int ret = get_rtlsdr_samples(sample, 1, opts, state);
if (ret < 0) return -1;
return 0;
}