1 files changed, 1094 insertions, 0 deletions

diff --git a/apps/plugins/pdbox/PDa/src/d_filter.c b/apps/plugins/pdbox/PDa/src/d_filter.c
new file mode 100644
index 0000000000..05bb7cd58e
--- /dev/null
+++ b/apps/plugins/pdbox/PDa/src/d_filter.c
@@ -0,0 +1,1094 @@
+/* Copyright (c) 1997-1999 Miller Puckette.
+* For information on usage and redistribution, and for a DISCLAIMER OF ALL
+* WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */
+
+/*  "filters", both linear and nonlinear. 
+*/
+#include "m_pd.h"
+#include <math.h>
+
+/* ---------------- hip~ - 1-pole 1-zero hipass filter. ----------------- */
+
+typedef struct hipctl
+{
+    float c_x;
+    float c_coef;
+} t_hipctl;
+
+typedef struct sighip
+{
+    t_object x_obj;
+    float x_sr;
+    float x_hz;
+    t_hipctl x_cspace;
+    t_hipctl *x_ctl;
+    float x_f;
+} t_sighip;
+
+t_class *sighip_class;
+static void sighip_ft1(t_sighip *x, t_floatarg f);
+
+static void *sighip_new(t_floatarg f)
+{
+    t_sighip *x = (t_sighip *)pd_new(sighip_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x = 0;
+    sighip_ft1(x, f);
+    x->x_f = 0;
+    return (x);
+}
+
+static void sighip_ft1(t_sighip *x, t_floatarg f)
+{
+    if (f < 0) f = 0;
+    x->x_hz = f;
+    x->x_ctl->c_coef = 1 - f * (2 * 3.14159) / x->x_sr;
+    if (x->x_ctl->c_coef < 0)
+        x->x_ctl->c_coef = 0;
+    else if (x->x_ctl->c_coef > 1)
+        x->x_ctl->c_coef = 1;
+}
+
+static t_int *sighip_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_hipctl *c = (t_hipctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x;
+    float coef = c->c_coef;
+    if (coef < 1)
+    {
+        for (i = 0; i < n; i++)
+        {
+            float new = *in++ + coef * last;
+            *out++ = new - last;
+            last = new;
+        }
+        if (PD_BIGORSMALL(last))
+            last = 0; 
+        c->c_x = last;
+    }
+    else
+    {
+        for (i = 0; i < n; i++)
+            *out++ = *in++;
+        c->c_x = 0;
+    }
+    return (w+5);
+}
+
+static void sighip_dsp(t_sighip *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    sighip_ft1(x,  x->x_hz);
+    dsp_add(sighip_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+static void sighip_clear(t_sighip *x, t_floatarg q)
+{
+    x->x_cspace.c_x = 0;
+}
+
+void sighip_setup(void)
+{
+    sighip_class = class_new(gensym("hip~"), (t_newmethod)sighip_new, 0,
+        sizeof(t_sighip), 0, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(sighip_class, t_sighip, x_f);
+    class_addmethod(sighip_class, (t_method)sighip_dsp, gensym("dsp"), 0);
+    class_addmethod(sighip_class, (t_method)sighip_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(sighip_class, (t_method)sighip_clear, gensym("clear"), 0);
+}
+
+/* ---------------- lop~ - 1-pole lopass filter. ----------------- */
+
+typedef struct lopctl
+{
+    float c_x;
+    float c_coef;
+} t_lopctl;
+
+typedef struct siglop
+{
+    t_object x_obj;
+    float x_sr;
+    float x_hz;
+    t_lopctl x_cspace;
+    t_lopctl *x_ctl;
+    float x_f;
+} t_siglop;
+
+t_class *siglop_class;
+
+static void siglop_ft1(t_siglop *x, t_floatarg f);
+
+static void *siglop_new(t_floatarg f)
+{
+    t_siglop *x = (t_siglop *)pd_new(siglop_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x = 0;
+    siglop_ft1(x, f);
+    x->x_f = 0;
+    return (x);
+}
+
+static void siglop_ft1(t_siglop *x, t_floatarg f)
+{
+    if (f < 0) f = 0;
+    x->x_hz = f;
+    x->x_ctl->c_coef = f * (2 * 3.14159) / x->x_sr;
+    if (x->x_ctl->c_coef > 1)
+        x->x_ctl->c_coef = 1;
+    else if (x->x_ctl->c_coef < 0)
+        x->x_ctl->c_coef = 0;
+}
+
+static void siglop_clear(t_siglop *x, t_floatarg q)
+{
+    x->x_cspace.c_x = 0;
+}
+
+static t_int *siglop_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_lopctl *c = (t_lopctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x;
+    float coef = c->c_coef;
+    float feedback = 1 - coef;
+    for (i = 0; i < n; i++)
+        last = *out++ = coef * *in++ + feedback * last;
+    if (PD_BIGORSMALL(last))
+        last = 0;
+    c->c_x = last;
+    return (w+5);
+}
+
+static void siglop_dsp(t_siglop *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    siglop_ft1(x,  x->x_hz);
+    dsp_add(siglop_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void siglop_setup(void)
+{
+    siglop_class = class_new(gensym("lop~"), (t_newmethod)siglop_new, 0,
+        sizeof(t_siglop), 0, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(siglop_class, t_siglop, x_f);
+    class_addmethod(siglop_class, (t_method)siglop_dsp, gensym("dsp"), 0);
+    class_addmethod(siglop_class, (t_method)siglop_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(siglop_class, (t_method)siglop_clear, gensym("clear"), 0);
+}
+
+/* ---------------- bp~ - 2-pole bandpass filter. ----------------- */
+
+typedef struct bpctl
+{
+    float c_x1;
+    float c_x2;
+    float c_coef1;
+    float c_coef2;
+    float c_gain;
+} t_bpctl;
+
+typedef struct sigbp
+{
+    t_object x_obj;
+    float x_sr;
+    float x_freq;
+    float x_q;
+    t_bpctl x_cspace;
+    t_bpctl *x_ctl;
+    float x_f;
+} t_sigbp;
+
+t_class *sigbp_class;
+
+static void sigbp_docoef(t_sigbp *x, t_floatarg f, t_floatarg q);
+
+static void *sigbp_new(t_floatarg f, t_floatarg q)
+{
+    t_sigbp *x = (t_sigbp *)pd_new(sigbp_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft2"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x1 = 0;
+    x->x_cspace.c_x2 = 0;
+    sigbp_docoef(x, f, q);
+    x->x_f = 0;
+    return (x);
+}
+
+static float sigbp_qcos(float f)
+{
+    if (f >= -(0.5f*3.14159f) && f <= 0.5f*3.14159f)
+    {
+        float g = f*f;
+        return (((g*g*g * (-1.0f/720.0f) + g*g*(1.0f/24.0f)) - g*0.5) + 1);
+    }
+    else return (0);
+}
+
+static void sigbp_docoef(t_sigbp *x, t_floatarg f, t_floatarg q)
+{
+    float r, oneminusr, omega;
+    if (f < 0.001) f = 10;
+    if (q < 0) q = 0;
+    x->x_freq = f;
+    x->x_q = q;
+    omega = f * (2.0f * 3.14159f) / x->x_sr;
+    if (q < 0.001) oneminusr = 1.0f;
+    else oneminusr = omega/q;
+    if (oneminusr > 1.0f) oneminusr = 1.0f;
+    r = 1.0f - oneminusr;
+    x->x_ctl->c_coef1 = 2.0f * sigbp_qcos(omega) * r;
+    x->x_ctl->c_coef2 = - r * r;
+    x->x_ctl->c_gain = 2 * oneminusr * (oneminusr + r * omega);
+    /* post("r %f, omega %f, coef1 %f, coef2 %f",
+        r, omega, x->x_ctl->c_coef1, x->x_ctl->c_coef2); */
+}
+
+static void sigbp_ft1(t_sigbp *x, t_floatarg f)
+{
+    sigbp_docoef(x, f, x->x_q);
+}
+
+static void sigbp_ft2(t_sigbp *x, t_floatarg q)
+{
+    sigbp_docoef(x, x->x_freq, q);
+}
+
+static void sigbp_clear(t_sigbp *x, t_floatarg q)
+{
+    x->x_ctl->c_x1 = x->x_ctl->c_x2 = 0;
+}
+
+static t_int *sigbp_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_bpctl *c = (t_bpctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x1;
+    float prev = c->c_x2;
+    float coef1 = c->c_coef1;
+    float coef2 = c->c_coef2;
+    float gain = c->c_gain;
+    for (i = 0; i < n; i++)
+    {
+        float output =  *in++ + coef1 * last + coef2 * prev;
+        *out++ = gain * output;
+        prev = last;
+        last = output;
+    }
+    if (PD_BIGORSMALL(last))
+        last = 0;
+    if (PD_BIGORSMALL(prev))
+        prev = 0;
+    c->c_x1 = last;
+    c->c_x2 = prev;
+    return (w+5);
+}
+
+static void sigbp_dsp(t_sigbp *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    sigbp_docoef(x, x->x_freq, x->x_q);
+    dsp_add(sigbp_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void sigbp_setup(void)
+{
+    sigbp_class = class_new(gensym("bp~"), (t_newmethod)sigbp_new, 0,
+        sizeof(t_sigbp), 0, A_DEFFLOAT, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(sigbp_class, t_sigbp, x_f);
+    class_addmethod(sigbp_class, (t_method)sigbp_dsp, gensym("dsp"), 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_ft2,
+        gensym("ft2"), A_FLOAT, 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_clear, gensym("clear"), 0);
+}
+
+/* ---------------- biquad~ - raw biquad filter ----------------- */
+
+typedef struct biquadctl
+{
+    float c_x1;
+    float c_x2;
+    float c_fb1;
+    float c_fb2;
+    float c_ff1;
+    float c_ff2;
+    float c_ff3;
+} t_biquadctl;
+
+typedef struct sigbiquad
+{
+    t_object x_obj;
+    float x_f;
+    t_biquadctl x_cspace;
+    t_biquadctl *x_ctl;
+} t_sigbiquad;
+
+t_class *sigbiquad_class;
+
+static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv);
+
+static void *sigbiquad_new(t_symbol *s, int argc, t_atom *argv)
+{
+    t_sigbiquad *x = (t_sigbiquad *)pd_new(sigbiquad_class);
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x1 = x->x_cspace.c_x2 = 0;
+    sigbiquad_list(x, s, argc, argv);
+    x->x_f = 0;
+    return (x);
+}
+
+static t_int *sigbiquad_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_biquadctl *c = (t_biquadctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x1;
+    float prev = c->c_x2;
+    float fb1 = c->c_fb1;
+    float fb2 = c->c_fb2;
+    float ff1 = c->c_ff1;
+    float ff2 = c->c_ff2;
+    float ff3 = c->c_ff3;
+    for (i = 0; i < n; i++)
+    {
+        float output =  *in++ + fb1 * last + fb2 * prev;
+        if (PD_BIGORSMALL(output))
+            output = 0; 
+        *out++ = ff1 * output + ff2 * last + ff3 * prev;
+        prev = last;
+        last = output;
+    }
+    c->c_x1 = last;
+    c->c_x2 = prev;
+    return (w+5);
+}
+
+static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
+{
+    float fb1 = atom_getfloatarg(0, argc, argv);
+    float fb2 = atom_getfloatarg(1, argc, argv);
+    float ff1 = atom_getfloatarg(2, argc, argv);
+    float ff2 = atom_getfloatarg(3, argc, argv);
+    float ff3 = atom_getfloatarg(4, argc, argv);
+    float discriminant = fb1 * fb1 + 4 * fb2;
+    t_biquadctl *c = x->x_ctl;
+    if (discriminant < 0) /* imaginary roots -- resonant filter */
+    {
+            /* they're conjugates so we just check that the product
+            is less than one */
+        if (fb2 >= -1.0f) goto stable;
+    }
+    else    /* real roots */
+    {
+            /* check that the parabola 1 - fb1 x - fb2 x^2 has a
+                vertex between -1 and 1, and that it's nonnegative
+                at both ends, which implies both roots are in [1-,1]. */
+        if (fb1 <= 2.0f && fb1 >= -2.0f &&
+            1.0f - fb1 -fb2 >= 0 && 1.0f + fb1 - fb2 >= 0)
+                goto stable;
+    }
+        /* if unstable, just bash to zero */
+    fb1 = fb2 = ff1 = ff2 = ff3 = 0;
+stable:
+    c->c_fb1 = fb1;
+    c->c_fb2 = fb2;
+    c->c_ff1 = ff1;
+    c->c_ff2 = ff2;
+    c->c_ff3 = ff3;
+}
+
+static void sigbiquad_set(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
+{
+    t_biquadctl *c = x->x_ctl;
+    c->c_x1 = atom_getfloatarg(0, argc, argv);
+    c->c_x2 = atom_getfloatarg(1, argc, argv);
+}
+
+static void sigbiquad_dsp(t_sigbiquad *x, t_signal **sp)
+{
+    dsp_add(sigbiquad_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void sigbiquad_setup(void)
+{
+    sigbiquad_class = class_new(gensym("biquad~"), (t_newmethod)sigbiquad_new,
+        0, sizeof(t_sigbiquad), 0, A_GIMME, 0);
+    CLASS_MAINSIGNALIN(sigbiquad_class, t_sigbiquad, x_f);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_dsp, gensym("dsp"), 0);
+    class_addlist(sigbiquad_class, sigbiquad_list);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("set"),
+        A_GIMME, 0);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("clear"),
+        A_GIMME, 0);
+}
+
+/* ---------------- samphold~ - sample and hold  ----------------- */
+
+typedef struct sigsamphold
+{
+    t_object x_obj;
+    float x_f;
+    float x_lastin;
+    float x_lastout;
+} t_sigsamphold;
+
+t_class *sigsamphold_class;
+
+static void *sigsamphold_new(void)
+{
+    t_sigsamphold *x = (t_sigsamphold *)pd_new(sigsamphold_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_lastin = 0;
+    x->x_lastout = 0;
+    x->x_f = 0;
+    return (x);
+}
+
+static t_int *sigsamphold_perform(t_int *w)
+{
+    float *in1 = (float *)(w[1]);
+    float *in2 = (float *)(w[2]);
+    float *out = (float *)(w[3]);
+    t_sigsamphold *x = (t_sigsamphold *)(w[4]);
+    int n = (t_int)(w[5]);
+    int i;
+    float lastin = x->x_lastin;
+    float lastout = x->x_lastout;
+    for (i = 0; i < n; i++, *in1++)
+    {
+        float next = *in2++;
+        if (next < lastin) lastout = *in1;
+        *out++ = lastout;
+        lastin = next;
+    }
+    x->x_lastin = lastin;
+    x->x_lastout = lastout;
+    return (w+6);
+}
+
+static void sigsamphold_dsp(t_sigsamphold *x, t_signal **sp)
+{
+    dsp_add(sigsamphold_perform, 5,
+        sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, 
+            x, sp[0]->s_n);
+}
+
+static void sigsamphold_reset(t_sigsamphold *x)
+{
+    x->x_lastin = 1e20;
+}
+
+static void sigsamphold_set(t_sigsamphold *x, t_float f)
+{
+    x->x_lastout = f;
+}
+
+void sigsamphold_setup(void)
+{
+    sigsamphold_class = class_new(gensym("samphold~"),
+        (t_newmethod)sigsamphold_new, 0, sizeof(t_sigsamphold), 0, 0);
+    CLASS_MAINSIGNALIN(sigsamphold_class, t_sigsamphold, x_f);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_set,
+        gensym("set"), A_FLOAT, 0);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_reset,
+        gensym("reset"), 0);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_dsp,
+        gensym("dsp"), 0);
+}
+
+/* ------------------------ setup routine ------------------------- */
+
+void d_filter_setup(void)
+{
+    sighip_setup();
+    siglop_setup();
+    sigbp_setup();
+    sigbiquad_setup();
+    sigsamphold_setup();
+}
+/* Copyright (c) 1997-1999 Miller Puckette.
+* For information on usage and redistribution, and for a DISCLAIMER OF ALL
+* WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */
+
+/*  "filters", both linear and nonlinear. 
+*/
+#include "m_pd.h"
+#include <math.h>
+
+/* ---------------- hip~ - 1-pole 1-zero hipass filter. ----------------- */
+
+typedef struct hipctl
+{
+    float c_x;
+    float c_coef;
+} t_hipctl;
+
+typedef struct sighip
+{
+    t_object x_obj;
+    float x_sr;
+    float x_hz;
+    t_hipctl x_cspace;
+    t_hipctl *x_ctl;
+    float x_f;
+} t_sighip;
+
+t_class *sighip_class;
+static void sighip_ft1(t_sighip *x, t_floatarg f);
+
+static void *sighip_new(t_floatarg f)
+{
+    t_sighip *x = (t_sighip *)pd_new(sighip_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x = 0;
+    sighip_ft1(x, f);
+    x->x_f = 0;
+    return (x);
+}
+
+static void sighip_ft1(t_sighip *x, t_floatarg f)
+{
+    if (f < 0) f = 0;
+    x->x_hz = f;
+    x->x_ctl->c_coef = 1 - f * (2 * 3.14159) / x->x_sr;
+    if (x->x_ctl->c_coef < 0)
+        x->x_ctl->c_coef = 0;
+    else if (x->x_ctl->c_coef > 1)
+        x->x_ctl->c_coef = 1;
+}
+
+static t_int *sighip_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_hipctl *c = (t_hipctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x;
+    float coef = c->c_coef;
+    if (coef < 1)
+    {
+        for (i = 0; i < n; i++)
+        {
+            float new = *in++ + coef * last;
+            *out++ = new - last;
+            last = new;
+        }
+        if (PD_BIGORSMALL(last))
+            last = 0; 
+        c->c_x = last;
+    }
+    else
+    {
+        for (i = 0; i < n; i++)
+            *out++ = *in++;
+        c->c_x = 0;
+    }
+    return (w+5);
+}
+
+static void sighip_dsp(t_sighip *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    sighip_ft1(x,  x->x_hz);
+    dsp_add(sighip_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+static void sighip_clear(t_sighip *x, t_floatarg q)
+{
+    x->x_cspace.c_x = 0;
+}
+
+void sighip_setup(void)
+{
+    sighip_class = class_new(gensym("hip~"), (t_newmethod)sighip_new, 0,
+        sizeof(t_sighip), 0, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(sighip_class, t_sighip, x_f);
+    class_addmethod(sighip_class, (t_method)sighip_dsp, gensym("dsp"), 0);
+    class_addmethod(sighip_class, (t_method)sighip_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(sighip_class, (t_method)sighip_clear, gensym("clear"), 0);
+}
+
+/* ---------------- lop~ - 1-pole lopass filter. ----------------- */
+
+typedef struct lopctl
+{
+    float c_x;
+    float c_coef;
+} t_lopctl;
+
+typedef struct siglop
+{
+    t_object x_obj;
+    float x_sr;
+    float x_hz;
+    t_lopctl x_cspace;
+    t_lopctl *x_ctl;
+    float x_f;
+} t_siglop;
+
+t_class *siglop_class;
+
+static void siglop_ft1(t_siglop *x, t_floatarg f);
+
+static void *siglop_new(t_floatarg f)
+{
+    t_siglop *x = (t_siglop *)pd_new(siglop_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x = 0;
+    siglop_ft1(x, f);
+    x->x_f = 0;
+    return (x);
+}
+
+static void siglop_ft1(t_siglop *x, t_floatarg f)
+{
+    if (f < 0) f = 0;
+    x->x_hz = f;
+    x->x_ctl->c_coef = f * (2 * 3.14159) / x->x_sr;
+    if (x->x_ctl->c_coef > 1)
+        x->x_ctl->c_coef = 1;
+    else if (x->x_ctl->c_coef < 0)
+        x->x_ctl->c_coef = 0;
+}
+
+static void siglop_clear(t_siglop *x, t_floatarg q)
+{
+    x->x_cspace.c_x = 0;
+}
+
+static t_int *siglop_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_lopctl *c = (t_lopctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x;
+    float coef = c->c_coef;
+    float feedback = 1 - coef;
+    for (i = 0; i < n; i++)
+        last = *out++ = coef * *in++ + feedback * last;
+    if (PD_BIGORSMALL(last))
+        last = 0;
+    c->c_x = last;
+    return (w+5);
+}
+
+static void siglop_dsp(t_siglop *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    siglop_ft1(x,  x->x_hz);
+    dsp_add(siglop_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void siglop_setup(void)
+{
+    siglop_class = class_new(gensym("lop~"), (t_newmethod)siglop_new, 0,
+        sizeof(t_siglop), 0, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(siglop_class, t_siglop, x_f);
+    class_addmethod(siglop_class, (t_method)siglop_dsp, gensym("dsp"), 0);
+    class_addmethod(siglop_class, (t_method)siglop_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(siglop_class, (t_method)siglop_clear, gensym("clear"), 0);
+}
+
+/* ---------------- bp~ - 2-pole bandpass filter. ----------------- */
+
+typedef struct bpctl
+{
+    float c_x1;
+    float c_x2;
+    float c_coef1;
+    float c_coef2;
+    float c_gain;
+} t_bpctl;
+
+typedef struct sigbp
+{
+    t_object x_obj;
+    float x_sr;
+    float x_freq;
+    float x_q;
+    t_bpctl x_cspace;
+    t_bpctl *x_ctl;
+    float x_f;
+} t_sigbp;
+
+t_class *sigbp_class;
+
+static void sigbp_docoef(t_sigbp *x, t_floatarg f, t_floatarg q);
+
+static void *sigbp_new(t_floatarg f, t_floatarg q)
+{
+    t_sigbp *x = (t_sigbp *)pd_new(sigbp_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft1"));
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("float"), gensym("ft2"));
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_sr = 44100;
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x1 = 0;
+    x->x_cspace.c_x2 = 0;
+    sigbp_docoef(x, f, q);
+    x->x_f = 0;
+    return (x);
+}
+
+static float sigbp_qcos(float f)
+{
+    if (f >= -(0.5f*3.14159f) && f <= 0.5f*3.14159f)
+    {
+        float g = f*f;
+        return (((g*g*g * (-1.0f/720.0f) + g*g*(1.0f/24.0f)) - g*0.5) + 1);
+    }
+    else return (0);
+}
+
+static void sigbp_docoef(t_sigbp *x, t_floatarg f, t_floatarg q)
+{
+    float r, oneminusr, omega;
+    if (f < 0.001) f = 10;
+    if (q < 0) q = 0;
+    x->x_freq = f;
+    x->x_q = q;
+    omega = f * (2.0f * 3.14159f) / x->x_sr;
+    if (q < 0.001) oneminusr = 1.0f;
+    else oneminusr = omega/q;
+    if (oneminusr > 1.0f) oneminusr = 1.0f;
+    r = 1.0f - oneminusr;
+    x->x_ctl->c_coef1 = 2.0f * sigbp_qcos(omega) * r;
+    x->x_ctl->c_coef2 = - r * r;
+    x->x_ctl->c_gain = 2 * oneminusr * (oneminusr + r * omega);
+    /* post("r %f, omega %f, coef1 %f, coef2 %f",
+        r, omega, x->x_ctl->c_coef1, x->x_ctl->c_coef2); */
+}
+
+static void sigbp_ft1(t_sigbp *x, t_floatarg f)
+{
+    sigbp_docoef(x, f, x->x_q);
+}
+
+static void sigbp_ft2(t_sigbp *x, t_floatarg q)
+{
+    sigbp_docoef(x, x->x_freq, q);
+}
+
+static void sigbp_clear(t_sigbp *x, t_floatarg q)
+{
+    x->x_ctl->c_x1 = x->x_ctl->c_x2 = 0;
+}
+
+static t_int *sigbp_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_bpctl *c = (t_bpctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x1;
+    float prev = c->c_x2;
+    float coef1 = c->c_coef1;
+    float coef2 = c->c_coef2;
+    float gain = c->c_gain;
+    for (i = 0; i < n; i++)
+    {
+        float output =  *in++ + coef1 * last + coef2 * prev;
+        *out++ = gain * output;
+        prev = last;
+        last = output;
+    }
+    if (PD_BIGORSMALL(last))
+        last = 0;
+    if (PD_BIGORSMALL(prev))
+        prev = 0;
+    c->c_x1 = last;
+    c->c_x2 = prev;
+    return (w+5);
+}
+
+static void sigbp_dsp(t_sigbp *x, t_signal **sp)
+{
+    x->x_sr = sp[0]->s_sr;
+    sigbp_docoef(x, x->x_freq, x->x_q);
+    dsp_add(sigbp_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void sigbp_setup(void)
+{
+    sigbp_class = class_new(gensym("bp~"), (t_newmethod)sigbp_new, 0,
+        sizeof(t_sigbp), 0, A_DEFFLOAT, A_DEFFLOAT, 0);
+    CLASS_MAINSIGNALIN(sigbp_class, t_sigbp, x_f);
+    class_addmethod(sigbp_class, (t_method)sigbp_dsp, gensym("dsp"), 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_ft1,
+        gensym("ft1"), A_FLOAT, 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_ft2,
+        gensym("ft2"), A_FLOAT, 0);
+    class_addmethod(sigbp_class, (t_method)sigbp_clear, gensym("clear"), 0);
+}
+
+/* ---------------- biquad~ - raw biquad filter ----------------- */
+
+typedef struct biquadctl
+{
+    float c_x1;
+    float c_x2;
+    float c_fb1;
+    float c_fb2;
+    float c_ff1;
+    float c_ff2;
+    float c_ff3;
+} t_biquadctl;
+
+typedef struct sigbiquad
+{
+    t_object x_obj;
+    float x_f;
+    t_biquadctl x_cspace;
+    t_biquadctl *x_ctl;
+} t_sigbiquad;
+
+t_class *sigbiquad_class;
+
+static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv);
+
+static void *sigbiquad_new(t_symbol *s, int argc, t_atom *argv)
+{
+    t_sigbiquad *x = (t_sigbiquad *)pd_new(sigbiquad_class);
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_ctl = &x->x_cspace;
+    x->x_cspace.c_x1 = x->x_cspace.c_x2 = 0;
+    sigbiquad_list(x, s, argc, argv);
+    x->x_f = 0;
+    return (x);
+}
+
+static t_int *sigbiquad_perform(t_int *w)
+{
+    float *in = (float *)(w[1]);
+    float *out = (float *)(w[2]);
+    t_biquadctl *c = (t_biquadctl *)(w[3]);
+    int n = (t_int)(w[4]);
+    int i;
+    float last = c->c_x1;
+    float prev = c->c_x2;
+    float fb1 = c->c_fb1;
+    float fb2 = c->c_fb2;
+    float ff1 = c->c_ff1;
+    float ff2 = c->c_ff2;
+    float ff3 = c->c_ff3;
+    for (i = 0; i < n; i++)
+    {
+        float output =  *in++ + fb1 * last + fb2 * prev;
+        if (PD_BIGORSMALL(output))
+            output = 0; 
+        *out++ = ff1 * output + ff2 * last + ff3 * prev;
+        prev = last;
+        last = output;
+    }
+    c->c_x1 = last;
+    c->c_x2 = prev;
+    return (w+5);
+}
+
+static void sigbiquad_list(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
+{
+    float fb1 = atom_getfloatarg(0, argc, argv);
+    float fb2 = atom_getfloatarg(1, argc, argv);
+    float ff1 = atom_getfloatarg(2, argc, argv);
+    float ff2 = atom_getfloatarg(3, argc, argv);
+    float ff3 = atom_getfloatarg(4, argc, argv);
+    float discriminant = fb1 * fb1 + 4 * fb2;
+    t_biquadctl *c = x->x_ctl;
+    if (discriminant < 0) /* imaginary roots -- resonant filter */
+    {
+            /* they're conjugates so we just check that the product
+            is less than one */
+        if (fb2 >= -1.0f) goto stable;
+    }
+    else    /* real roots */
+    {
+            /* check that the parabola 1 - fb1 x - fb2 x^2 has a
+                vertex between -1 and 1, and that it's nonnegative
+                at both ends, which implies both roots are in [1-,1]. */
+        if (fb1 <= 2.0f && fb1 >= -2.0f &&
+            1.0f - fb1 -fb2 >= 0 && 1.0f + fb1 - fb2 >= 0)
+                goto stable;
+    }
+        /* if unstable, just bash to zero */
+    fb1 = fb2 = ff1 = ff2 = ff3 = 0;
+stable:
+    c->c_fb1 = fb1;
+    c->c_fb2 = fb2;
+    c->c_ff1 = ff1;
+    c->c_ff2 = ff2;
+    c->c_ff3 = ff3;
+}
+
+static void sigbiquad_set(t_sigbiquad *x, t_symbol *s, int argc, t_atom *argv)
+{
+    t_biquadctl *c = x->x_ctl;
+    c->c_x1 = atom_getfloatarg(0, argc, argv);
+    c->c_x2 = atom_getfloatarg(1, argc, argv);
+}
+
+static void sigbiquad_dsp(t_sigbiquad *x, t_signal **sp)
+{
+    dsp_add(sigbiquad_perform, 4,
+        sp[0]->s_vec, sp[1]->s_vec, 
+            x->x_ctl, sp[0]->s_n);
+
+}
+
+void sigbiquad_setup(void)
+{
+    sigbiquad_class = class_new(gensym("biquad~"), (t_newmethod)sigbiquad_new,
+        0, sizeof(t_sigbiquad), 0, A_GIMME, 0);
+    CLASS_MAINSIGNALIN(sigbiquad_class, t_sigbiquad, x_f);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_dsp, gensym("dsp"), 0);
+    class_addlist(sigbiquad_class, sigbiquad_list);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("set"),
+        A_GIMME, 0);
+    class_addmethod(sigbiquad_class, (t_method)sigbiquad_set, gensym("clear"),
+        A_GIMME, 0);
+}
+
+/* ---------------- samphold~ - sample and hold  ----------------- */
+
+typedef struct sigsamphold
+{
+    t_object x_obj;
+    float x_f;
+    float x_lastin;
+    float x_lastout;
+} t_sigsamphold;
+
+t_class *sigsamphold_class;
+
+static void *sigsamphold_new(void)
+{
+    t_sigsamphold *x = (t_sigsamphold *)pd_new(sigsamphold_class);
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_lastin = 0;
+    x->x_lastout = 0;
+    x->x_f = 0;
+    return (x);
+}
+
+static t_int *sigsamphold_perform(t_int *w)
+{
+    float *in1 = (float *)(w[1]);
+    float *in2 = (float *)(w[2]);
+    float *out = (float *)(w[3]);
+    t_sigsamphold *x = (t_sigsamphold *)(w[4]);
+    int n = (t_int)(w[5]);
+    int i;
+    float lastin = x->x_lastin;
+    float lastout = x->x_lastout;
+    for (i = 0; i < n; i++, *in1++)
+    {
+        float next = *in2++;
+        if (next < lastin) lastout = *in1;
+        *out++ = lastout;
+        lastin = next;
+    }
+    x->x_lastin = lastin;
+    x->x_lastout = lastout;
+    return (w+6);
+}
+
+static void sigsamphold_dsp(t_sigsamphold *x, t_signal **sp)
+{
+    dsp_add(sigsamphold_perform, 5,
+        sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, 
+            x, sp[0]->s_n);
+}
+
+static void sigsamphold_reset(t_sigsamphold *x)
+{
+    x->x_lastin = 1e20;
+}
+
+static void sigsamphold_set(t_sigsamphold *x, t_float f)
+{
+    x->x_lastout = f;
+}
+
+void sigsamphold_setup(void)
+{
+    sigsamphold_class = class_new(gensym("samphold~"),
+        (t_newmethod)sigsamphold_new, 0, sizeof(t_sigsamphold), 0, 0);
+    CLASS_MAINSIGNALIN(sigsamphold_class, t_sigsamphold, x_f);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_set,
+        gensym("set"), A_FLOAT, 0);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_reset,
+        gensym("reset"), 0);
+    class_addmethod(sigsamphold_class, (t_method)sigsamphold_dsp,
+        gensym("dsp"), 0);
+}
+
+/* ------------------------ setup routine ------------------------- */
+
+void d_filter_setup(void)
+{
+    sighip_setup();
+    siglop_setup();
+    sigbp_setup();
+    sigbiquad_setup();
+    sigsamphold_setup();
+}