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#include <string.h>
#include <alsa/asoundlib.h>
#include "midi.h"
#define BACKEND_NAME "midi"
static snd_seq_t* sequencer = NULL;
/*
* TODO
* Optionally send note-off messages
*/
enum /*_midi_channel_type*/ {
none = 0,
note,
cc,
sysmsg
};
int midi_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(snd_seq_open(&sequencer, "default", SND_SEQ_OPEN_DUPLEX, 0) < 0){
fprintf(stderr, "Failed to open ALSA sequencer\n");
return 1;
}
//register backend
if(mm_backend_register(midi)){
fprintf(stderr, "Failed to register MIDI backend\n");
return 1;
}
return 0;
}
static int midi_configure(char* option, char* value){
if(!strcmp(option, "name")){
if(snd_seq_set_client_name(sequencer, value) < 0){
fprintf(stderr, "Failed to set MIDI client name to %s\n", value);
return 1;
}
return 0;
}
fprintf(stderr, "Unknown MIDI backend option %s\n", option);
return 1;
}
static instance* midi_instance(){
return mm_instance();
}
static int midi_configure_instance(instance* instance, char* option, char* value){
if(!strcmp(option, "device")){
//open i/o device
return 0;
}
else if(!strcmp(option, "port")){
//create midi port
return 0;
}
else if(!strcmp(option, "mode")){
//configure open mode
//FIXME needed?
return 0;
}
fprintf(stderr, "Unknown MIDI instance option %s\n", option);
return 1;
}
static channel* midi_channel(instance* instance, char* spec){
union {
struct {
uint8_t pad[5];
uint8_t type;
uint8_t channel;
uint8_t control;
} fields;
uint64_t label;
} ident = {
.label = 0
};
char* channel;
if(!strncmp(spec, "cc", 2)){
ident.fields.type = cc;
channel = spec + 2;
}
else if(!strncmp(spec, "note", 4)){
ident.fields.type = note;
channel = spec + 4;
}
else{
fprintf(stderr, "Unknown MIDI channel specification %s\n", spec);
return NULL;
}
ident.fields.channel = strtoul(channel, &channel, 10);
//FIXME test this
if(ident.fields.channel > 16){
fprintf(stderr, "Channel out of range in channel spec %s\n", spec);
return NULL;
}
if(*channel != '.'){
fprintf(stderr, "Need MIDI channel specification of form channel.control, had %s\n", spec);
return NULL;
}
channel++;
ident.fields.control = strtoul(channel, NULL, 10);
if(ident.label){
return mm_channel(instance, ident.label);
}
return NULL;
}
static int midi_set(size_t num, channel* c, channel_value* v){
//TODO
return 1;
}
static int midi_handle(size_t num, int* fd, void** data){
//TODO
return 1;
}
static int midi_start(){
return 1;
}
static int midi_shutdown(){
size_t n, p;
instance** inst = NULL;
if(mm_backend_instances(BACKEND_NAME, &n, &inst)){
fprintf(stderr, "Failed to fetch instance list\n");
return 1;
}
for(p = 0; p < n; p++){
free(inst[p]->impl);
}
free(inst);
//close midi
snd_seq_close(sequencer);
sequencer = NULL;
//free configuration cache
snd_config_update_free_global();
fprintf(stderr, "MIDI backend shut down\n");
return 0;
}
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