Hello list,

I need some help understanding whats going on with my external, and I havent coded in a long time. I appologize if I do newbie things, All I do is try to make the errors go away by trying things. For example I try to cast (t_float *) to (float) for truncf but I get errors unless I make *(t_float *)...

Problem 1, Basic functionality. I want to return the Nth sample from a block of samples. Is others have pointed out there may be other ways of doing this using other externals and combonations of objects, but I want to write my own object, in order to both learn more about writing externals, and to have a cleaner solution.

Problem 2, Weird errors. I get a werid warning: implicit declaration of function `truncf' when using a simple math.h function, and if I connect my external to fft~ while enabling a small piece of code I color the FFT~ output. When I then disconnect my object, the fft~ stops putting output out.

Problem 1: a closer look. Ive included my code at the bottom of this email. I really appreciate if someone could point out what Im doing wrong. Ive looked at snapshot~ and tried to adopt some of its methods, but it doesnt seem to work when compaired to print~ output.

Problem 2: a closer look. The peice of code: int n = (int)(w[3]); t_float *bin = (t_float *)(w[4]); *bin = truncf(*bin); if (*bin > n) *bin = n; if (*bin < 0) *bin = 0; Gives me the error: warning: implicit declaration of function `truncf'. Im not redefining the function... Also when this piece of code is enabled, and I connect to FFT~ real output I get colored output, then when I break the connection, FFT~ doesnt output anything, it seems. w[3]=sp[0]->s_n - 1 w[4]=&ref->x_bin t_float x_bin;

-------------The Code----------------- #include <m_pd.h> #include <math.h>

/*-------------------------------------------------------*/ /*fftbin~ */ /* A tool to extract specific bins from the output of */ /* fft~. Inlets are (from left to right): */ /* The output of fft~ and bang, the bin number to */ /* capture. */ /* The outlet is a control rate float equal to the value */ /* of the bin in question. */ /*-------------------------------------------------------*/

static t_class *fftbin_tilde_class;

typedef struct _fftbin { t_object x_obj; t_float x_n; t_float x_bin; t_float x_binval; float x_f; } t_fftbin;

void *fftbin_tilde_new(t_floatarg f) { t_fftbin *ref = (t_fftbin *)pd_new(fftbin_tilde_class); ref->x_bin = f; ref->x_binval=0; ref->x_f = 0; ref->x_n=64; //Signal inlet exists by default outlet_new(&ref->x_obj, &s_float); //bin value outlet floatinlet_new(&ref->x_obj, &ref->x_bin); //bin number inlet return (void *)ref; }

t_int *fftbin_tilde_perform(t_int *w) { t_float *in1 = (t_float *)(w[1]); //fft~ output t_float *binval = (t_float *)(w[2]); //value requested int n = (int)(w[3]); //block size t_float *bin = (t_float *)(w[4]); //bin request

//make sure bin requested is within block, and an integer *bin = truncf(*bin); if (*bin > n) *bin = n; if (*bin < 0) *bin = 0;

*binval = *in1;

return (w+5); }

void fftbin_tilde_dsp(t_fftbin *ref, t_signal **sp) { dsp_add(fftbin_tilde_perform, 4, sp[0]->s_vec + (int)ref->x_bin, &ref->x_binval, sp[0]->s_n - 1, &ref->x_bin); }

void fftbin_tilde_set(t_fftbin *ref, t_floatarg f) { ref->x_bin = f; }

void fftbin_tilde_bang(t_fftbin *ref) { outlet_float(ref->x_obj.ob_outlet, ref->x_binval); }

void fftbin_tilde_setup(void) { fftbin_tilde_class = class_new(gensym("fftbin~"), (t_newmethod)fftbin_tilde_new, 0, sizeof(t_fftbin), CLASS_DEFAULT, A_DEFFLOAT, 0);

class_addmethod(fftbin_tilde_class, (t_method)fftbin_tilde_dsp, gensym("dsp"), 0); class_addmethod(fftbin_tilde_class, (t_method)fftbin_tilde_set, gensym("set"), A_DEFFLOAT, 0); class_addbang(fftbin_tilde_class, fftbin_tilde_bang);

CLASS_MAINSIGNALIN(fftbin_tilde_class, t_fftbin, x_f); post("fftbin~: written by thewade with help from the PD list"); }