1 files changed, 131 insertions, 0 deletions
diff --git a/flib/src/cross~.c b/flib/src/cross~.c
new file mode 100644
index 0000000..d769e54
--- /dev/null
+++ b/flib/src/cross~.c
@@ -0,0 +1,131 @@
+/* flib - PD library for feature extraction 
+   Copyright (C) 2005  Jamie Bullock
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+   */
+
+
+/*Calculate the (non optimized) cross correlation of two signal vectors*/
+
+#include "flib.h"
+#define SQ(a) (a * a)
+
+static t_class *cross_class;
+
+typedef struct _cross {
+    t_object  x_obj;
+    t_float f;
+    t_int delay;
+} t_cross;
+
+static t_int *cross_perform(t_int *w)
+{
+    t_sample *x = (t_sample *)(w[1]);
+    t_sample *y = (t_sample *)(w[2]);
+    t_sample *out = (t_sample *)(w[3]);
+    t_int N = (t_int)(w[4]),
+	  i, j, delay;
+    t_int maxdelay = (t_int)(w[5]);
+    t_float mx, my, sx, sy, sxy, denom, r;
+  
+   if(maxdelay > N * .5){
+	maxdelay = N * .5;
+	post("cross~: invalid maxdelay, must be <= blocksize/2");
+   }
+ 
+   /* Calculate the mean of the two series x[], y[] */
+   mx = 0;
+   my = 0;   
+   for (i=0;i<N;i++) {
+      mx += x[i];
+      my += y[i];
+   }
+   mx /= N;
+   my /= N;
+
+   /* Calculate the denominator */
+   sx = 0;
+   sy = 0;
+   for (i=0;i<N;i++) {
+      sx += (x[i] - mx) * (x[i] - mx);
+      sy += (y[i] - my) * (y[i] - my);
+   }
+   denom = sqrt(sx*sy);
+
+   /* Calculate the correlation series */
+   for (delay=-maxdelay;delay<maxdelay;delay++) {
+      sxy = 0;
+      for (i=0;i<N;i++) {
+         j = i + delay;
+
+	/* circular correlation */
+	 while (j < 0)
+            j += N;
+         j %= N;
+         sxy += (x[i] - mx) * (y[j] - my);
+
+
+    /*  
+	   if (j < 0 || j >= N)
+            continue;
+         else
+            sxy += (x[i] - mx) * (y[j] - my);
+        */ 
+
+
+	/* Or should it be (?)
+         if (j < 0 || j >= n)
+            sxy += (x[i] - mx) * (-my);
+         else
+            sxy += (x[i] - mx) * (y[j] - my);
+         */
+      }
+      r = sxy / denom;
+	*out++ = r;
+      /* r is the correlation coefficient at "delay" */
+
+   }
+
+  return (w+6);
+
+}
+
+static void cross_dsp(t_cross *x, t_signal **sp)
+{
+    dsp_add(cross_perform, 5,
+	    sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[0]->s_n, x->delay);
+}
+
+static void *cross_new(t_floatarg f)
+{
+    t_cross *x = (t_cross *)pd_new(cross_class);
+    x->delay = (t_int)f;
+    inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
+    outlet_new(&x->x_obj, &s_signal);
+    return (void *)x;
+}
+
+
+void cross_tilde_setup(void) {
+    cross_class = class_new(gensym("cross~"),
+	    (t_newmethod)cross_new,
+	    0, sizeof(t_cross),
+	    CLASS_DEFAULT, A_DEFFLOAT, 0);
+
+    class_addmethod(cross_class,
+	    (t_method)cross_dsp, gensym("dsp"), 0);
+    CLASS_MAINSIGNALIN(cross_class, t_cross,f);
+    class_sethelpsymbol(cross_class, gensym("help-flib"));
+}