aboutsummaryrefslogtreecommitdiff
path: root/pd/doc/6.externs
diff options
context:
space:
mode:
Diffstat (limited to 'pd/doc/6.externs')
-rw-r--r--pd/doc/6.externs/dspobj~.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/pd/doc/6.externs/dspobj~.c b/pd/doc/6.externs/dspobj~.c
index a8841f21..5c3fa86b 100644
--- a/pd/doc/6.externs/dspobj~.c
+++ b/pd/doc/6.externs/dspobj~.c
@@ -12,9 +12,16 @@ static t_class *dspobj_class;
typedef struct _dspobj
{
- t_object x_obj;
+ t_object x_obj; /* obligatory header */
+ t_float x_f; /* place to hold inlet's value if it's set by message */
} t_dspobj;
+ /* this is the actual performance routine which acts on the samples.
+ It's called with a single pointer "w" which is our location in the
+ DSP call list. We return a new "w" which will point to the next item
+ after us. Meanwhile, w[0] is just a pointer to dsp-perform itself
+ (no use to us), w[1] and w[2] are the input and output vector locations,
+ and w[3] is the number of points to calculate. */
static t_int *dspobj_perform(t_int *w)
{
t_float *in = (t_float *)(w[1]);
@@ -28,6 +35,9 @@ static t_int *dspobj_perform(t_int *w)
return (w+4);
}
+ /* called to start DSP. Here we call Pd back to add our perform
+ routine to a linear callback list which Pd in turn calls to grind
+ out the samples. */
static void dspobj_dsp(t_dspobj *x, t_signal **sp)
{
dsp_add(dspobj_perform, 3, sp[0]->s_vec, sp[1]->s_vec, sp[0]->s_n);
@@ -37,13 +47,21 @@ static void *dspobj_new(void)
{
t_dspobj *x = (t_dspobj *)pd_new(dspobj_class);
outlet_new(&x->x_obj, gensym("signal"));
+ x->x_f = 0;
return (x);
}
+ /* this routine, which must have exactly this name (with the "~" replaced
+ by "_tilde) is called when the code is first loaded, and tells Pd how
+ to build the "class". */
void dspobj_tilde_setup(void)
{
dspobj_class = class_new(gensym("dspobj~"), (t_newmethod)dspobj_new, 0,
sizeof(t_dspobj), 0, A_DEFFLOAT, 0);
- class_addmethod(dspobj_class, nullfn, gensym("signal"), 0);
+ /* this is magic to declare that the leftmost, "main" inlet
+ takes signals; other signal inlets are done differently... */
+ CLASS_MAINSIGNALIN(dspobj_class, t_dspobj, x_f);
+ /* here we tell Pd about the "dsp" method, which is called back
+ when DSP is turned on. */
class_addmethod(dspobj_class, (t_method)dspobj_dsp, gensym("dsp"), 0);
}