Files
looper/src/looper.c
Loic Coenen bb648d471b fix: resolve cppcheck warnings for const pointer and static functions
Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>
2026-05-12 19:58:20 +00:00

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// cppcheck-suppress missingIncludeSystem
#include "looper.h"
#include "channel.h"
#include "midi.h"
#include "wav.h"
#include <jack/jack.h>
#include <jack/midiport.h>
#include <math.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
/* Global state (shared across files) */
struct channel_t channels[MAX_CHANNELS];
atomic_int channel_count = 0;
int next_channel_id = 1;
atomic_int cmd_add = 0;
atomic_int cmd_remove = 0;
atomic_int cmd_load = 0;
atomic_int cmd_save = 0;
jack_port_t *midi_control_port = NULL;
jack_port_t *midi_clock_port = NULL;
atomic_int control_key_active = 0;
atomic_int bind_channel = 0;
/* Deferred removal index (1 second grace) */
static int pending_unregister_idx = -1;
/* writer thread function and sample rate holder */
static void *writer_thread(void *arg);
static int global_sample_rate = 0;
/* ----------------------------------------------------------------
* process callback
* ---------------------------------------------------------------- */
int process_callback(jack_nframes_t nframes, void *arg) {
(void)arg;
if (midi_control_port) {
void *midi_ctrl_buf = jack_port_get_buffer(midi_control_port, nframes);
if (midi_ctrl_buf) {
midi_handle_events(midi_ctrl_buf, nframes);
}
}
/* process each active channel */
for (int c = 0; c < MAX_CHANNELS; c++) {
if (!atomic_load(&channels[c].active))
continue;
/* Guard against NULL ports (e.g. if port registration failed) */
if (!channels[c].audio_in || !channels[c].audio_out) {
fprintf(stderr, "WARN: channel %d has NULL audio port(s), skipping\n", c);
continue;
}
const jack_default_audio_sample_t *in =
(const jack_default_audio_sample_t *)jack_port_get_buffer(
channels[c].audio_in, nframes);
jack_default_audio_sample_t *out =
(jack_default_audio_sample_t *)jack_port_get_buffer(
channels[c].audio_out, nframes);
if (!out)
continue;
int state = atomic_load(&channels[c].state);
if (state != atomic_load(&channels[c].prev_state)) {
switch (state) {
case STATE_RECORD:
atomic_store(&channels[c].record_pos, 0);
atomic_store(&channels[c].loop_count, 0);
break;
case STATE_LOOPING:
if (atomic_load(&channels[c].prev_state) == STATE_RECORD &&
atomic_load(&channels[c].record_pos) > 0)
atomic_store(&channels[c].loop_count,
atomic_load(&channels[c].record_pos));
atomic_store(&channels[c].playback_pos, 0);
break;
default:
break;
}
}
jack_nframes_t i;
switch (state) {
case STATE_RECORD:
if (in) {
float *f_out = (float *)out;
const float *f_in = (const float *)in;
for (i = 0; i < nframes; i++) {
int rp = atomic_fetch_add(&channels[c].record_pos, 1);
if (rp < LOOP_BUF_SIZE)
channels[c].loop_buffer[rp] = f_in[i];
f_out[i] = f_in[i];
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
case STATE_LOOPING:
int lc = atomic_load(&channels[c].loop_count);
if (lc > 0) {
float *outf = (float *)out;
for (i = 0; i < nframes; i++) {
int pp = atomic_load(&channels[c].playback_pos);
outf[i] = channels[c].loop_buffer[pp];
atomic_store(&channels[c].playback_pos, (pp + 1) % lc);
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
case STATE_PAUSED:
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
break;
default: /* IDLE */
if (in) {
memcpy(out, in, sizeof(jack_default_audio_sample_t) * nframes);
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
}
// push loop output into save ring if saving (atomic load)
RingBuf *r = (RingBuf *)atomic_load_explicit(&channels[c].save_ring,
memory_order_acquire);
if (r != NULL) {
if (state == STATE_LOOPING && atomic_load(&channels[c].loop_count) > 0) {
const float *outf = (const float *)out;
ring_write(r, outf, nframes);
}
}
atomic_store(&channels[c].prev_state, state);
}
/* MIDI clock events affect channel 0 only */
if (midi_clock_port) {
void *midi_clock_buf = jack_port_get_buffer(midi_clock_port, nframes);
if (midi_clock_buf) {
jack_nframes_t n_clock_events = jack_midi_get_event_count(midi_clock_buf);
jack_midi_event_t cev;
for (jack_nframes_t j = 0; j < n_clock_events; j++) {
if (jack_midi_event_get(&cev, midi_clock_buf, j) != 0)
continue;
if (cev.size >= 1) {
unsigned char msg = cev.buffer[0];
switch (msg) {
case 0xFA: {
int s = atomic_load(&channels[0].state);
if (s == STATE_IDLE)
atomic_store(&channels[0].state, STATE_RECORD);
break;
}
case 0xFC:
atomic_store(&channels[0].state, STATE_IDLE);
break;
case 0xFB: {
int s = atomic_load(&channels[0].state);
if (s == STATE_PAUSED)
atomic_store(&channels[0].state, STATE_LOOPING);
break;
}
default:
break;
}
}
}
}
}
return 0;
}
/* ----------------------------------------------------------------
* shutdown callback
* ---------------------------------------------------------------- */
void jack_shutdown_cb(void *arg) {
(void)arg;
fprintf(stderr, "JACK shutdown\n");
exit(0);
}
/* ----------------------------------------------------------------
* looper initialisation
* ---------------------------------------------------------------- */
int looper_init(jack_client_t *client) {
/* store sample rate for writer thread */
global_sample_rate = jack_get_sample_rate(client);
/* channel 0 */
channels[0].active = 1;
atomic_store(&channels[0].state, STATE_IDLE);
atomic_store(&channels[0].prev_state, -1);
channels[0].loop_count = 0;
atomic_store(&channels[0].record_pos, 0);
atomic_store(&channels[0].playback_pos, 0);
atomic_store_explicit(&channels[0].save_ring, NULL, memory_order_release);
channels[0].audio_in = jack_port_register(
client, "input", JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
channels[0].audio_out = jack_port_register(
client, "output", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
if (!channels[0].audio_in || !channels[0].audio_out) {
fprintf(stderr, "Could not create audio ports for channel 0\n");
return -1;
}
channel_count = 1;
midi_control_port = jack_port_register(
client, "control", JACK_DEFAULT_MIDI_TYPE, JackPortIsInput, 0);
midi_clock_port = jack_port_register(client, "clock", JACK_DEFAULT_MIDI_TYPE,
JackPortIsInput, 0);
if (!midi_control_port || !midi_clock_port) {
fprintf(stderr, "Could not create MIDI ports\n");
return -1;
}
return 0;
}
/* ----------------------------------------------------------------
* writer thread consumes the save ring and writes WAV file
* ---------------------------------------------------------------- */
static void *writer_thread(void *arg) {
struct channel_t *ch = (struct channel_t *)arg;
RingBuf *ring = (RingBuf *)ch->save_ring;
if (!ring)
return NULL;
static const char *path = "save.wav";
unsigned sr = (unsigned)global_sample_rate;
if (sr == 0)
sr = 48000;
int lc = atomic_load(&ch->loop_count);
float *outbuf = malloc((size_t)lc * sizeof(float));
if (!outbuf) {
ring_destroy(ring);
free(ring);
ch->save_ring = NULL;
return NULL;
}
size_t collected = 0;
size_t want = (size_t)lc;
while (collected < want) {
size_t got = ring_read(ring, outbuf + collected, want - collected);
collected += got;
if (got == 0) {
struct timespec req = {.tv_sec = 0, .tv_nsec = 10000000};
nanosleep(&req, NULL);
}
}
wav_write(path, outbuf, (unsigned)lc, sr);
free(outbuf);
ring_destroy(ring);
free(ring);
atomic_store_explicit(&ch->save_ring, NULL, memory_order_release);
return NULL;
}
/* ----------------------------------------------------------------
* mainloop command processing
* ---------------------------------------------------------------- */
void looper_process_commands(jack_client_t *client) {
/* Unregister any ports that were marked for deferred removal.
By now the realtime thread has had at least one full cycle
to see the `active = 0` store. */
if (pending_unregister_idx != -1) {
int idx = pending_unregister_idx;
if (channels[idx].audio_in)
jack_port_unregister(client, channels[idx].audio_in);
if (channels[idx].audio_out)
jack_port_unregister(client, channels[idx].audio_out);
pending_unregister_idx = -1;
}
if (atomic_exchange(&cmd_add, 0)) {
int idx;
for (idx = 0; idx < MAX_CHANNELS; idx++)
if (!channels[idx].active)
break;
if (idx < MAX_CHANNELS) {
channel_add(client, idx);
}
}
if (atomic_exchange(&cmd_remove, 0)) {
int remove_idx = -1;
for (int idx = 1; idx < MAX_CHANNELS; idx++)
if (channels[idx].active)
remove_idx = idx;
if (remove_idx != -1) {
/* Mark inactive now; ports will be unregistered next round */
channel_remove(client, remove_idx);
pending_unregister_idx = remove_idx;
}
}
/* ---------- load command ---------- */
if (atomic_exchange(&cmd_load, 0)) {
float *buf = NULL;
unsigned frames = 0;
printf("LOAD: wav_read called\n");
if (wav_read("loop.wav", &buf, &frames) == 0 && frames > 0) {
printf("LOAD: success, frames=%u\n", frames);
if (frames > LOOP_BUF_SIZE)
frames = LOOP_BUF_SIZE;
memcpy(channels[0].loop_buffer, buf, frames * sizeof(float));
atomic_store(&channels[0].loop_count, (int)frames);
atomic_store(&channels[0].record_pos, 0);
atomic_store(&channels[0].playback_pos, 0);
atomic_store(&channels[0].state, STATE_LOOPING);
atomic_store(&channels[0].prev_state, -1);
free(buf);
} else {
fprintf(stderr, "Failed to load loop.wav\n");
printf("LOAD: FAILED\n");
}
}
/* ---------- save command (writer thread) ---------- */
if (atomic_exchange(&cmd_save, 0)) {
int lc = atomic_load(&channels[0].loop_count);
if (atomic_load(&channels[0].state) == STATE_LOOPING && lc > 0 &&
channels[0].save_ring == NULL) {
RingBuf *ring = (RingBuf *)malloc(sizeof(RingBuf));
if (ring) {
size_t sz = (size_t)lc * 2;
if (ring_init(ring, sz) == 0) {
atomic_store_explicit(&channels[0].save_ring, (_Atomic RingBuf *)ring,
memory_order_release);
pthread_t th;
pthread_create(&th, NULL, writer_thread, &channels[0]);
pthread_detach(th);
} else {
free(ring);
}
}
}
}
}