hi,
here's my "template" for a threaded external. i had to use pthread,
because polling an usb device was causing glitches in pd. since i didn't
want to have 2 instance of pd (1 for polling usb + netsend, 1 for audio
+ netreceive) i came up with this solution. i am sure it's dirty and
unstable, but at least no more glitches...
if anyone can tight it up, it could be a nice template for anyone who
wants to build a thread safe external!
pat
#include "m_pd.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pthread.h"
typedef struct _pdexterna
{
t_object p_ob; // object header - ALL pd external MUST begin with this...
void *outlets[OUTLETS]; // handle to the objects outlets
int x_verbose;
pthread_attr_t pdexterna_thread_attr;
pthread_t x_threadid;
} t_pdexterna;
void *pdexterna_class; // global pointer to the object class - so pd can reference the object
// ==============================================================================
// Function Prototypes
// ------------------------------------------------------------------------------
void *pdexterna_new(t_symbol *s);
void pdexterna_bang(t_pdexterna *x);
// =============================================================================
// Thread crap
// =============================================================================
static void *usb_thread_read(void *w)
{
t_pdexterna *x = (t_pdexterna*) w;
while(1) {
pthread_testcancel();
//sys_lock();
pdexterna_bang(x);
//sys_unlock();
}
}
static void usb_thread_start(t_pdexterna *x)
{
// create the worker thread
if(pthread_attr_init(&x->pdexterna_thread_attr) < 0)
{
error("pdexterna: could not launch receive thread");
return;
}
if(pthread_attr_setdetachstate(&x->pdexterna_thread_attr, PTHREAD_CREATE_DETACHED) < 0)
{
error("pdexterna: could not launch receive thread");
return;
}
if(pthread_create(&x->x_threadid, &x->pdexterna_thread_attr, usb_thread_read, x) < 0)
{
error("pdexterna: could not launch receive thread");
return;
}
else
{
if(x->x_verbose)post("pdexterna: thread %d launched", (int)x->x_threadid );
}
}
//--------------------------------------------------------------------------
// - Message: bang -> poll pdexterna
//--------------------------------------------------------------------------
void pdexterna_bang(t_pdexterna *x) // poll pdexterna
{
//whatever
}
//--------------------------------------------------------------------------
// - Object creation and setup
//--------------------------------------------------------------------------
int pdexterna_setup(void)
{
pdexterna_class = class_new ( gensym("pdexterna"),(t_newmethod)pdexterna_new, 0, sizeof(t_pdexterna), CLASS_DEFAULT,0);
// Add message handlers
class_addbang(pdexterna_class, (t_method)pdexterna_bang);
post("pdexterna version 0.1",0);
return 1;
}
//--------------------------------------------------------------------------
void *pdexterna_new(t_symbol *s) // s = optional argument typed into object box (A_SYM) -- defaults to 0 if no args are typed
{
t_pdexterna *x; // local variable (pointer to a t_pdexterna data structure)
x = (t_pdexterna *)pd_new(pdexterna_class); // create a new instance of this object
x->x_verbose = 1;
int i;
// create outlets and assign it to our outlet variable in the instance's data structure
for (i=0; i < OUTLETS; i++) {
x->outlets[i] = outlet_new(&x->p_ob, &s_float);
}
usb_thread_start(x);
return x; // return a reference to the object instance
}
//--------------------------------------------------------------------------
// - Object destruction
//--------------------------------------------------------------------------
void pdexterna_free(t_pdexterna *x)
{
while(pthread_cancel(x->x_threadid) < 0)
if(x->x_verbose)post("pdexterna: killing thread\n");
if(x->x_verbose)post("pdexterna: thread canceled\n");
}
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