Visualizza wikitesto di ALSA e Gambas: Creare 16 Client ciascuno avente 16 porte in Uscita e 16 porte in Entrata

Mostriamo un possibile codice per creare 16 Client autonomi, ciascuno avente 16 porte in Uscita e 16 porte in Entrata:
 Library "libasound:2"
 
 Private Const SND_SEQ_OPEN_DUPLEX As Integer = 3
 Private Const SND_SEQ_PORT_CAP_READ As Integer = 1
 Private Const SND_SEQ_PORT_CAP_SUBS_READ As Integer = 32
 Private Const SND_SEQ_PORT_CAP_WRITE As Integer = 2
 Private Const SND_SEQ_PORT_CAP_SUBS_WRITE As Integer = 64
 <FONT color=gray>''Private Const SND_SEQ_PORT_TYPE_MIDI_GENERIC As Integer = 2''
 ''Private Const SND_SEQ_PORT_TYPE_APPLICATION As Integer = 1048576''</font>
 
 
 <FONT color=gray>' ''int snd_seq_open (snd_seq_t **handle, const char *name, int streams, int mode)''
 ' ''Open the ALSA sequencer.''</font>
 Private Extern snd_seq_open(seqP As Pointer, name As String, streams As Integer, mode As Integer) As Integer
 
 <FONT color=gray>' ''int snd_seq_set_client_name(snd_seq_t * seq, const char * name)''
 ' ''Set client name.''</font>
 Private Extern snd_seq_set_client_name(seqP As Pointer, name As String) As Integer
 
 <FONT color=gray>' ''int snd_seq_client_id(snd_seq_t * seq)''
 ' ''Get the client id.''</font>
 Private Extern snd_seq_client_id(seqP As Pointer) As Integer
 
 <FONT color=gray>' ''int snd_seq_create_simple_port(snd_seq_t* seq, const char* name, unsigned int caps, unsigned int type)''
 ' ''Create a port - simple version.''</font>
 Private Extern snd_seq_create_simple_port(seqP As Pointer, name As String, caps As Integer, type As Integer) As Integer
 
 <FONT color=gray>' ''int snd_seq_connect_to (snd_seq_t *seq, int my_port, int dest_client, int dest_port)''
 ' ''Simple subscription (w/o exclusive & time conversion).''</font>
 Private Extern snd_seq_connect_to(seq As Pointer, myport As Integer, dest_client As Integer, dest_port As Integer) As Integer
 
 <FONT color=gray>' ''int snd_seq_connect_from (snd_seq_t *seq, int my_port, int src_client, int src_port)''
 ' ''Simple subscription (w/o exclusive & time conversion).''</font>
 Private Extern snd_seq_connect_from(seq As Pointer, myport As Integer, src_client As Integer, src_port As Integer) As Integer
 
 <FONT color=gray>' ''const char * snd_strerror (int errnum)''
 ' ''Returns the message for an error code.''</font>
 Private Extern snd_strerror(err As Integer) As Pointer
 
 
 '''Public''' Sub Main()
 
  Dim err, id, extra, intra As Integer
  Dim hp As New Pointer[]
  Dim handle As Pointer
  Dim nomen As String
  Dim b, c As Byte
  
 
   For b = 0 To 15
   
     err = snd_seq_open(VarPtr(handle), "default", SND_SEQ_OPEN_DUPLEX, 0)
     If err < 0 Then Error.Raise("Errore nell'apertura di Alsa: " & snd_strerror(err))
  
     hp.Add(handle)
  
     nomen = "'Client n. " & CStr(b) & "'"
     snd_seq_set_client_name(hp[b], nomen)
     Print "\nNOME del Client: "; nomen
 
     id = snd_seq_client_id(hp[b])
     Print "ID del Client: "; id
  
     For c = 0 To 15
 <FONT color=gray>' ''Crea la porta in Uscita del Client:''</font>
       extra = snd_seq_create_simple_port(hp[b], "Porta di Uscita", 0, SND_SEQ_PORT_CAP_READ + SND_SEQ_PORT_CAP_SUBS_READ) <FONT color=gray>' ''oppure: SND_SEQ_PORT_TYPE_MIDI_GENERIC + SND_SEQ_PORT_TYPE_APPLICATION)''</font>
       If extra < 0 Then
         Error.Raise("Errore nella creazione della porta in Uscita del Client: " & snd_strerror(extra))
       Else
         Print "Porta in Uscita del Client: "; extra;
       Endif
    
 <FONT color=gray>' ''Crea la porta in Entrata del Client:''</font>
       intra = snd_seq_create_simple_port(hp[b], "Porta di Entrata", 0, SND_SEQ_PORT_CAP_WRITE + SND_SEQ_PORT_CAP_SUBS_WRITE) <FONT color=gray>' ''oppure: SND_SEQ_PORT_TYPE_MIDI_GENERIC + SND_SEQ_PORT_TYPE_APPLICATION)''</font>
       If intra < 0 Then
         Error.Raise("Errore nella creazione della porta in Entrata del Client: " & snd_strerror(intra))
       Else
         Print "    Porta in Entrata del Client: "; intra
       Endif
    
       impostaConnessioni(hp[b], extra, intra)
    
     Next
   
   Next
 
   While True
     Wait 0.01
   Wend
 
 '''End'''
 
 
 '''Public''' Sub impostaConnessioni(seq As Pointer, portEx As Integer, portIn As Integer)
 
  Dim err As Integer
 
 <FONT color=gray>' ''Connettiamo la corrente porta di Uscita del nostro Client''
 ' ''ad esempio alla porta n. 0 di entrata del Client avente Id 14 ('Midi Through'):''</font>
   err = snd_seq_connect_to(seq, portEx, 14, 0)
   If err < 0 Then error.Raise("Errore nella sottoscrizione del dispositivo !")
 
 <FONT color=gray>' ''Connettiamo la corrente porta di Entrata del nostro Client''
 ' ''alla porta di uscita di un dispositivo esterno Midi (ad esempio ad una tastiera Midi):''</font>
   err = snd_seq_connect_from(seq, portIn, 24, 0)
   If err < 0 Then error.Raise("Errore nella sottoscrizione del dispositivo !")
 
 '''End'''