/* miniFMsynth 1.0 by Matthias Nagorni    *//* This program uses callback-based audio *//* playback as proposed by Paul Davis on  *//* the linux-audio-dev mailinglist.       */#include <stdio.h>   #include <stdlib.h>#include <alsa/asoundlib.h>#include <math.h>#define POLY 10#define GAIN 5000.0#define BUFSIZE 512snd_seq_t *seq_handle;snd_pcm_t *playback_handle;short *buf;double phi[POLY], phi_mod[POLY], pitch, modulation, velocity[POLY], attack, decay, sustain, release, env_time[POLY], env_level[POLY];int harmonic, subharmonic, transpose, note[POLY], gate[POLY], note_active[POLY];snd_seq_t *open_seq() {    snd_seq_t *seq_handle;        if (snd_seq_open(&seq_handle, "default", SND_SEQ_OPEN_DUPLEX, 0) < 0) {        fprintf(stderr, "Error opening ALSA sequencer.\n");        exit(1);    }    snd_seq_set_client_name(seq_handle, "miniFMsynth");    if (snd_seq_create_simple_port(seq_handle, "miniFMsynth",        SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE,        SND_SEQ_PORT_TYPE_APPLICATION) < 0) {        fprintf(stderr, "Error creating sequencer port.\n");        exit(1);    }    return(seq_handle);}snd_pcm_t *open_pcm(char *pcm_name) {    snd_pcm_t *playback_handle;    snd_pcm_hw_params_t *hw_params;    snd_pcm_sw_params_t *sw_params;                if (snd_pcm_open (&playback_handle, pcm_name, SND_PCM_STREAM_PLAYBACK, 0) < 0) {        fprintf (stderr, "cannot open audio device %s\n", pcm_name);        exit (1);    }    snd_pcm_hw_params_alloca(&hw_params);    snd_pcm_hw_params_any(playback_handle, hw_params);    snd_pcm_hw_params_set_access(playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);    snd_pcm_hw_params_set_format(playback_handle, hw_params, SND_PCM_FORMAT_S16_LE);    snd_pcm_hw_params_set_rate_near(playback_handle, hw_params, 44100, 0);    snd_pcm_hw_params_set_channels(playback_handle, hw_params, 2);    snd_pcm_hw_params_set_periods(playback_handle, hw_params, 2, 0);    snd_pcm_hw_params_set_period_size(playback_handle, hw_params, BUFSIZE, 0);    snd_pcm_hw_params(playback_handle, hw_params);    snd_pcm_sw_params_alloca(&sw_params);    snd_pcm_sw_params_current(playback_handle, sw_params);    snd_pcm_sw_params_set_avail_min(playback_handle, sw_params, BUFSIZE);    snd_pcm_sw_params(playback_handle, sw_params);    return(playback_handle);}double envelope(int *note_active, int gate, double *env_level, double t, double attack, double decay, double sustain, double release) {    if (gate)  {        if (t > attack + decay) return(*env_level = sustain);        if (t > attack) return(*env_level = 1.0 - (1.0 - sustain) * (t - attack) / decay);        return(*env_level = t / attack);    } else {        if (t > release) {            if (note_active) *note_active = 0;            return(*env_level = 0);        }        return(*env_level * (1.0 - t / release));    }}int midi_callback() {    snd_seq_event_t *ev;    int l1;      do {        snd_seq_event_input(seq_handle, &ev);        switch (ev->type) {            case SND_SEQ_EVENT_PITCHBEND:                pitch = (double)ev->data.control.value / 8192.0;                break;            case SND_SEQ_EVENT_CONTROLLER:                if (ev->data.control.param == 1) {                    modulation = (double)ev->data.control.value / 10.0;                }                 break;            case SND_SEQ_EVENT_NOTEON:                for (l1 = 0; l1 < POLY; l1++) {                    if (!note_active[l1]) {                        note[l1] = ev->data.note.note;                        velocity[l1] = ev->data.note.velocity / 127.0;                        env_time[l1] = 0;                        gate[l1] = 1;                        note_active[l1] = 1;                        break;                    }                }                break;                    case SND_SEQ_EVENT_NOTEOFF:                for (l1 = 0; l1 < POLY; l1++) {                    if (gate[l1] && note_active[l1] && (note[l1] == ev->data.note.note)) {                        env_time[l1] = 0;                        gate[l1] = 0;                    }                }                break;                }        snd_seq_free_event(ev);    } while (snd_seq_event_input_pending(seq_handle, 0) > 0);    return (0);}int playback_callback (snd_pcm_sframes_t nframes) {    int l1, l2;    double dphi, dphi_mod, f1, f2, f3, freq_note, sound;          memset(buf, 0, nframes * 4);    for (l2 = 0; l2 < POLY; l2++) {        if (note_active[l2]) {            f1 = 8.176 * exp((double)(transpose+note[l2]-2)*log(2.0)/12.0);            f2 = 8.176 * exp((double)(transpose+note[l2])*log(2.0)/12.0);            f3 = 8.176 * exp((double)(transpose+note[l2]+2)*log(2.0)/12.0);            freq_note = (pitch > 0) ? f2 + (f3-f2)*pitch : f2 + (f2-f1)*pitch;            dphi = M_PI * freq_note / 22050.0;                                                dphi_mod = dphi * (double)harmonic / (double)subharmonic;            for (l1 = 0; l1 < nframes; l1++) {                phi[l2] += dphi;                phi_mod[l2] += dphi_mod;                if (phi[l2] > 2.0 * M_PI) phi[l2] -= 2.0 * M_PI;                if (phi_mod[l2] > 2.0 * M_PI) phi_mod[l2] -= 2.0 * M_PI;                sound = GAIN * envelope(&note_active[l2], gate[l2], &env_level[l2], env_time[l2], attack, decay, sustain, release)                             * velocity[l2] * sin(phi[l2] + modulation * sin(phi_mod[l2]));                env_time[l2] += 1.0 / 44100.0;                buf[2 * l1] += sound;                buf[2 * l1 + 1] += sound;            }        }        }    return snd_pcm_writei (playback_handle, buf, nframes); }      int main (int argc, char *argv[]) {    int nfds, seq_nfds, l1;    struct pollfd *pfds;        if (argc < 10) {        fprintf(stderr, "miniFMsynth <device> <FM> <harmonic> <subharmonic> <transpose> <a> <d> <s> <r>\n");         exit(1);    }    modulation = atof(argv[2]);    harmonic = atoi(argv[3]);    subharmonic = atoi(argv[4]);    transpose = atoi(argv[5]);    attack = atof(argv[6]);    decay = atof(argv[7]);    sustain = atof(argv[8]);    release = atof(argv[9]);    pitch = 0;    buf = (short *) malloc (2 * sizeof (short) * BUFSIZE);    playback_handle = open_pcm(argv[1]);    seq_handle = open_seq();    seq_nfds = snd_seq_poll_descriptors_count(seq_handle, POLLIN);    nfds = snd_pcm_poll_descriptors_count (playback_handle);    pfds = (struct pollfd *)alloca(sizeof(struct pollfd) * (seq_nfds + nfds));    snd_seq_poll_descriptors(seq_handle, pfds, seq_nfds, POLLIN);    snd_pcm_poll_descriptors (playback_handle, pfds+seq_nfds, nfds);    for (l1 = 0; l1 < POLY; note_active[l1++] = 0);    while (1) {        if (poll (pfds, seq_nfds + nfds, 1000) > 0) {            for (l1 = 0; l1 < seq_nfds; l1++) {               if (pfds[l1].revents > 0) midi_callback();            }            for (l1 = seq_nfds; l1 < seq_nfds + nfds; l1++) {                    if (pfds[l1].revents > 0) {                     if (playback_callback(BUFSIZE) < BUFSIZE) {                        fprintf (stderr, "xrun !\n");                        snd_pcm_prepare(playback_handle);                    }                }            }                }    }    snd_pcm_close (playback_handle);    snd_seq_close (seq_handle);    free(buf);    return (0);}