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path: root/src/step~.c
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/******************************************************
 *
 * zexy - implementation file
 *
 * copyleft (c) IOhannes m zmölnig
 *
 *   1999:forum::für::umläute:2004
 *
 *   institute of electronic music and acoustics (iem)
 *
 ******************************************************
 *
 * license: GNU General Public License v.2
 ******************************************************/

/*
step~  : will make a unity step at a desired point in the signal-vector; the second input specifies a 
			length:	after the so-specified time has elapsed, the step will toggle back to the previous
			value;
			the length can be passed as an argument when creating the object
			with length==1 you might do the dirac~ thing a little bit more complicated
			with length==0 the output just toggles between 0 and 1 every time you bang the object

NOTE : the inlets do NOT specify any times but sample-NUMBERS; there are 64 samples in a signal-vector,
		each "lasting" for 1/44100 secs.
*/

#include "zexy.h"

/* ------------------------ step~ ----------------------------- */ 

static t_class *step_class;

typedef struct _step
{
    t_object x_obj;
	int position;
	int length;

	int toggle;

	int wait4start;
	int wait4stop;
} t_step;

static void step_bang(t_step *x)
{
	x->wait4stop = x->length + (x->wait4start = x->position);
}

static void step_float(t_step *x, t_float where)
{
	x->wait4stop = x->length + 
		(x->wait4start =
			(x->position = (where>0)*where)
		);
}

static void step_setlength(t_step *x, t_float arg)
{
	x->length = 1 + (arg>0)*arg;
}



static t_int *step_perform(t_int *w)
{
	t_step *x = (t_step *)(w[1]);
    t_float *out = (t_float *)(w[2]);
    int n = (int)(w[3]);

	int toggle = x->toggle;

	int wait4start = x->wait4start, wait4stop = x->wait4stop;

	while (n--)
	{
		wait4stop--;
		if (!wait4start--) toggle ^= 1;
		else if (!wait4stop) toggle ^= 1;

		*out++ = toggle;		
	}

	x->wait4start = wait4start;
	x->wait4stop = wait4stop;

	x->toggle = toggle;
	return (w+4);
}

static void step_dsp(t_step *x, t_signal **sp)
{
	dsp_add(step_perform, 3, x, sp[0]->s_vec, sp[0]->s_n);
}


static void step_helper(void)
{
	post("%c step~-object :: generates a unity-step", HEARTSYMBOL);
	post("creation : \"dirac~ [<position> [<length>]]\" : create a rectangular window\n"
		"\t\t\tat specified position and with specified length (in samples)\n"
		 "inlet1\t: <position>\t: create a rectangular window at new position\n"
		 "\t  'bang'\t: create a rectangular window at specified position\n"
		 "\t  'help'\t: view this\n"
		 "inlet2\t: <length>\t: define new window length ('0' will make a unity-step)\n"
		 "outlet\t: signal~");
}


static void *step_new(t_floatarg farg)
{
	t_step *x = (t_step *)pd_new(step_class);

	inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
	outlet_new(&x->x_obj, gensym("signal"));

	x->position = 0;
	x->wait4start = x->wait4stop = 0;
	x->toggle = 1;

	step_setlength(x, farg);

	return (x);
}
 
void step_tilde_setup(void)
{
	step_class = class_new(gensym("step~"), (t_newmethod)step_new, 0,
		sizeof(t_step), 0, A_DEFFLOAT, 0);

	class_addfloat(step_class, step_float);
	class_addbang(step_class, step_bang); 
	class_addmethod(step_class, (t_method)step_setlength, gensym("ft1"), A_FLOAT, 0);
	class_addmethod(step_class, (t_method)step_dsp, gensym("dsp"), 0);

	class_addmethod(step_class, (t_method)step_helper, gensym("help"), 0);

  zexy_register("step~");
}