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#define BACKEND_NAME "midi"
#include <string.h>
#include <alsa/asoundlib.h>
#include "midi.h"
static char* sequencer_name = NULL;
static snd_seq_t* sequencer = NULL;
enum /*_midi_channel_type*/ {
none = 0,
note,
cc,
pressure,
aftertouch,
pitchbend,
rpn,
nrpn
};
static struct {
uint8_t detect;
} midi_config = {
.detect = 0
};
MM_PLUGIN_API int init(){
backend midi = {
.name = BACKEND_NAME,
.conf = midi_configure,
.create = midi_instance,
.conf_instance = midi_configure_instance,
.channel = midi_channel,
.handle = midi_set,
.process = midi_handle,
.start = midi_start,
.shutdown = midi_shutdown
};
if(sizeof(midi_channel_ident) != sizeof(uint64_t)){
LOG("Channel identification union out of bounds");
return 1;
}
//register backend
if(mm_backend_register(midi)){
LOG("Failed to register backend");
return 1;
}
return 0;
}
static int midi_configure(char* option, char* value){
if(!strcmp(option, "name")){
free(sequencer_name);
sequencer_name = strdup(value);
return 0;
}
else if(!strcmp(option, "detect")){
midi_config.detect = 1;
if(!strcmp(value, "off")){
midi_config.detect = 0;
}
return 0;
}
LOGPF("Unknown backend option %s", option);
return 1;
}
static int midi_instance(instance* inst){
inst->impl = calloc(1, sizeof(midi_instance_data));
if(!inst->impl){
LOG("Failed to allocate memory");
return 1;
}
return 0;
}
static int midi_configure_instance(instance* inst, char* option, char* value){
midi_instance_data* data = (midi_instance_data*) inst->impl;
//FIXME maybe allow connecting more than one device
if(!strcmp(option, "read")){
//connect input device
if(data->read){
LOGPF("Instance %s was already connected to an input device", inst->name);
return 1;
}
data->read = strdup(value);
return 0;
}
else if(!strcmp(option, "write")){
//connect output device
if(data->write){
LOGPF("Instance %s was already connected to an output device", inst->name);
return 1;
}
data->write = strdup(value);
return 0;
}
else if(!strcmp(option, "epn-tx")){
data->epn_tx_short = 0;
if(!strcmp(value, "short")){
data->epn_tx_short = 1;
}
return 0;
}
LOGPF("Unknown instance option %s", option);
return 1;
}
static channel* midi_channel(instance* inst, char* spec, uint8_t flags){
midi_channel_ident ident = {
.label = 0
};
char* channel = NULL;
if(!strncmp(spec, "ch", 2)){
channel = spec + 2;
if(!strncmp(spec, "channel", 7)){
channel = spec + 7;
}
}
if(!channel){
LOGPF("Invalid channel specification %s", spec);
return NULL;
}
ident.fields.channel = strtoul(channel, &channel, 10);
if(ident.fields.channel > 15){
LOGPF("MIDI channel out of range in spec %s", spec);
return NULL;
}
if(*channel != '.'){
LOGPF("Need specification of form channel<X>.<control><Y>, had %s", spec);
return NULL;
}
//skip the period
channel++;
if(!strncmp(channel, "cc", 2)){
ident.fields.type = cc;
channel += 2;
}
else if(!strncmp(channel, "note", 4)){
ident.fields.type = note;
channel += 4;
}
else if(!strncmp(channel, "pressure", 8)){
ident.fields.type = pressure;
channel += 8;
}
else if(!strncmp(channel, "rpn", 3)){
ident.fields.type = rpn;
channel += 3;
}
else if(!strncmp(channel, "nrpn", 4)){
ident.fields.type = nrpn;
channel += 4;
}
else if(!strncmp(channel, "pitch", 5)){
ident.fields.type = pitchbend;
}
else if(!strncmp(channel, "aftertouch", 10)){
ident.fields.type = aftertouch;
}
else{
LOGPF("Unknown control type in %s", spec);
return NULL;
}
ident.fields.control = strtoul(channel, NULL, 10);
if(ident.label){
return mm_channel(inst, ident.label, 1);
}
return NULL;
}
static void midi_tx(int port, uint8_t type, uint8_t channel, uint8_t control, uint16_t value){
snd_seq_event_t ev;
snd_seq_ev_clear(&ev);
snd_seq_ev_set_source(&ev, port);
snd_seq_ev_set_subs(&ev);
snd_seq_ev_set_direct(&ev);
switch(type){
case note:
snd_seq_ev_set_noteon(&ev, channel, control, value);
break;
case cc:
snd_seq_ev_set_controller(&ev, channel, control, value);
break;
case pressure:
snd_seq_ev_set_keypress(&ev, channel, control, value);
break;
case pitchbend:
snd_seq_ev_set_pitchbend(&ev, channel, value);
break;
case aftertouch:
snd_seq_ev_set_chanpress(&ev, channel, value);
break;
}
snd_seq_event_output(sequencer, &ev);
}
static int midi_set(instance* inst, size_t num, channel** c, channel_value* v){
size_t u;
midi_instance_data* data = (midi_instance_data*) inst->impl;
midi_channel_ident ident = {
.label = 0
};
for(u = 0; u < num; u++){
ident.label = c[u]->ident;
switch(ident.fields.type){
case rpn:
case nrpn:
//transmit parameter number
midi_tx(data->port, cc, ident.fields.channel, (ident.fields.type == rpn) ? 101 : 99, (ident.fields.control & 0x3F80) >> 7);
midi_tx(data->port, cc, ident.fields.channel, (ident.fields.type == rpn) ? 100 : 98, ident.fields.control & 0x7F);
//transmit parameter value
midi_tx(data->port, cc, ident.fields.channel, 6, (((uint16_t) (v[u].normalised * 16383.0)) & 0x3F80) >> 7);
midi_tx(data->port, cc, ident.fields.channel, 38, ((uint16_t) (v[u].normalised * 16383.0)) & 0x7F);
if(!data->epn_tx_short){
//clear active parameter
midi_tx(data->port, cc, ident.fields.channel, 101, 127);
midi_tx(data->port, cc, ident.fields.channel, 100, 127);
}
break;
case pitchbend:
midi_tx(data->port, ident.fields.type, ident.fields.channel, ident.fields.control, (v[u].normalised * 16383.0) - 8192);
break;
default:
midi_tx(data->port, ident.fields.type, ident.fields.channel, ident.fields.control, v[u].normalised * 127.0);
}
}
snd_seq_drain_output(sequencer);
return 0;
}
static char* midi_type_name(uint8_t type){
switch(type){
case none:
return "none";
case note:
return "note";
case cc:
return "cc";
case rpn:
return "rpn";
case nrpn:
return "nrpn";
case pressure:
return "pressure";
case aftertouch:
return "aftertouch";
case pitchbend:
return "pitch";
}
return "unknown";
}
static int midi_handle(size_t num, managed_fd* fds){
snd_seq_event_t* ev = NULL;
instance* inst = NULL;
channel* changed = NULL;
channel_value val;
char* event_type = NULL;
midi_channel_ident ident = {
.label = 0
};
if(!num){
return 0;
}
while(snd_seq_event_input(sequencer, &ev) > 0){
event_type = NULL;
ident.label = 0;
ident.fields.channel = ev->data.note.channel;
ident.fields.control = ev->data.note.note;
val.normalised = (double) ev->data.note.velocity / 127.0;
//TODO (n)rpn RX
switch(ev->type){
case SND_SEQ_EVENT_NOTEON:
case SND_SEQ_EVENT_NOTEOFF:
case SND_SEQ_EVENT_NOTE:
ident.fields.type = note;
if(ev->type == SND_SEQ_EVENT_NOTEOFF){
val.normalised = 0;
}
break;
case SND_SEQ_EVENT_KEYPRESS:
ident.fields.type = pressure;
break;
case SND_SEQ_EVENT_CHANPRESS:
ident.fields.type = aftertouch;
ident.fields.channel = ev->data.control.channel;
val.normalised = (double) ev->data.control.value / 127.0;
break;
case SND_SEQ_EVENT_PITCHBEND:
ident.fields.type = pitchbend;
ident.fields.channel = ev->data.control.channel;
val.normalised = ((double) ev->data.control.value + 8192) / 16383.0;
break;
case SND_SEQ_EVENT_CONTROLLER:
ident.fields.type = cc;
ident.fields.channel = ev->data.control.channel;
ident.fields.control = ev->data.control.param;
val.normalised = (double) ev->data.control.value / 127.0;
break;
default:
LOG("Ignored event of unsupported type");
continue;
}
event_type = midi_type_name(ident.fields.type);
inst = mm_instance_find(BACKEND_NAME, ev->dest.port);
if(!inst){
//FIXME might want to return failure
LOG("Delivered event did not match any instance");
continue;
}
changed = mm_channel(inst, ident.label, 0);
if(changed){
if(mm_channel_event(changed, val)){
free(ev);
return 1;
}
}
if(midi_config.detect && event_type){
if(ident.fields.type == pitchbend || ident.fields.type == aftertouch){
LOGPF("Incoming data on channel %s.ch%d.%s", inst->name, ident.fields.channel, event_type);
}
else{
LOGPF("Incoming data on channel %s.ch%d.%s%d", inst->name, ident.fields.channel, event_type, ident.fields.control);
}
}
}
free(ev);
return 0;
}
static int midi_start(size_t n, instance** inst){
size_t p;
int nfds, rv = 1;
struct pollfd* pfds = NULL;
midi_instance_data* data = NULL;
snd_seq_addr_t addr;
//connect to the sequencer
if(snd_seq_open(&sequencer, "default", SND_SEQ_OPEN_DUPLEX, 0) < 0){
LOG("Failed to open ALSA sequencer");
goto bail;
}
snd_seq_nonblock(sequencer, 1);
LOGPF("Client ID is %d", snd_seq_client_id(sequencer));
//update the sequencer client name
if(snd_seq_set_client_name(sequencer, sequencer_name ? sequencer_name : "MIDIMonster") < 0){
LOGPF("Failed to set client name to %s", sequencer_name);
goto bail;
}
//create all ports
for(p = 0; p < n; p++){
data = (midi_instance_data*) inst[p]->impl;
data->port = snd_seq_create_simple_port(sequencer, inst[p]->name, SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE | SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ, SND_SEQ_PORT_TYPE_MIDI_GENERIC);
inst[p]->ident = data->port;
//make connections
if(data->write){
if(snd_seq_parse_address(sequencer, &addr, data->write) == 0){
LOGPF("Connecting output of instance %s to device %s (%d:%d)", inst[p]->name, data->write, addr.client, addr.port);
snd_seq_connect_to(sequencer, data->port, addr.client, addr.port);
}
else{
LOGPF("Failed to get destination device address: %s", data->write);
}
free(data->write);
data->write = NULL;
}
if(data->read){
if(snd_seq_parse_address(sequencer, &addr, data->read) == 0){
LOGPF("Connecting input from device %s to instance %s (%d:%d)", data->read, inst[p]->name, addr.client, addr.port);
snd_seq_connect_from(sequencer, data->port, addr.client, addr.port);
}
else{
LOGPF("Failed to get source device address: %s", data->read);
}
free(data->read);
data->read = NULL;
}
}
//register all fds to core
nfds = snd_seq_poll_descriptors_count(sequencer, POLLIN | POLLOUT);
pfds = calloc(nfds, sizeof(struct pollfd));
if(!pfds){
LOG("Failed to allocate memory");
goto bail;
}
nfds = snd_seq_poll_descriptors(sequencer, pfds, nfds, POLLIN | POLLOUT);
LOGPF("Registering %d descriptors to core", nfds);
for(p = 0; p < nfds; p++){
if(mm_manage_fd(pfds[p].fd, BACKEND_NAME, 1, NULL)){
goto bail;
}
}
rv = 0;
bail:
free(pfds);
return rv;
}
static int midi_shutdown(size_t n, instance** inst){
size_t p;
midi_instance_data* data = NULL;
for(p = 0; p < n; p++){
data = (midi_instance_data*) inst[p]->impl;
free(data->read);
free(data->write);
data->read = NULL;
data->write = NULL;
free(inst[p]->impl);
}
//close midi
if(sequencer){
snd_seq_close(sequencer);
sequencer = NULL;
}
//free configuration cache
snd_config_update_free_global();
free(sequencer_name);
sequencer_name = NULL;
LOG("Backend shut down");
return 0;
}
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