1 files changed, 93 insertions, 0 deletions
diff --git a/src/spec2_sqrt~.c b/src/spec2_sqrt~.c
new file mode 100644
index 0000000..2701eec
--- /dev/null
+++ b/src/spec2_sqrt~.c
@@ -0,0 +1,93 @@
+/* For information on usage and redistribution, and for a DISCLAIMER OF ALL
+* WARRANTIES, see the file, "LICENSE.txt," in this distribution.
+
+iem_spec2 written by Thomas Musil, Copyright (c) IEM KUG Graz Austria 2000 - 2006 */
+
+#include "m_pd.h"
+#include "iemlib.h"
+#include <math.h>
+
+/* ------------------------ spec2_sqrt_tilde~ ------------------------- */
+
+static t_class *spec2_sqrt_tilde_class;
+
+#define SPEC2DUMTAB1SIZE 256
+#define SPEC2DUMTAB2SIZE 1024
+
+static t_float spec2_rsqrt_exptab[SPEC2DUMTAB1SIZE], spec2_rsqrt_mantissatab[SPEC2DUMTAB2SIZE];
+
+static void init_spec2_rsqrt(void)
+{
+  int i;
+  
+  for (i=0; i<SPEC2DUMTAB1SIZE; i++)
+  {
+    t_float f;
+    long l = (i ? (i == SPEC2DUMTAB1SIZE-1 ? SPEC2DUMTAB1SIZE-2 : i) : 1)<< 23;
+    
+    *(long *)(&f) = l;
+    spec2_rsqrt_exptab[i] = 1.0f/sqrt(f); 
+  }
+  
+  for (i=0; i<SPEC2DUMTAB2SIZE; i++)
+  {
+    t_float f = 1.0f + (1.0f / (t_float)SPEC2DUMTAB2SIZE) * (t_float)i;
+    
+    spec2_rsqrt_mantissatab[i] = 1.0f / sqrt(f);  
+  }
+}
+
+typedef struct _spec2_sqrt_tilde
+{
+  t_object  x_obj;
+  t_float   x_msi;
+} t_spec2_sqrt_tilde;
+
+static t_int *spec2_sqrt_tilde_perform(t_int *w)
+{
+  t_float *in = (t_float *)(w[1]);
+  t_float *out = (t_float *)(w[2]);
+  int n = w[3]+1;
+  
+  while(n--)
+  { 
+    t_float f = *in;
+    long l = *(long *)(in++);
+    
+    if(f < 0.0f)
+      *out++ = 0.0f;
+    else
+    {
+      t_float g = spec2_rsqrt_exptab[(l >> 23) & 0xff] * spec2_rsqrt_mantissatab[(l >> 13) & 0x3ff];
+      
+      *out++ = f*g*(1.5f - 0.5f*g*g*f);
+    }
+  }
+  return(w+4);
+}
+
+static void spec2_sqrt_tilde_dsp(t_spec2_sqrt_tilde *x, t_signal **sp)
+{
+  int n = (sp[0]->s_n)/2;
+  
+  dsp_add(spec2_sqrt_tilde_perform, 3, sp[0]->s_vec, sp[0]->s_vec, n);
+}
+
+static void *spec2_sqrt_tilde_new(void)
+{
+  t_spec2_sqrt_tilde *x = (t_spec2_sqrt_tilde *)pd_new(spec2_sqrt_tilde_class);
+  
+  outlet_new(&x->x_obj, &s_signal);
+  x->x_msi = 0.0f;
+  return (x);
+}
+
+void spec2_sqrt_tilde_setup(void)
+{
+  init_spec2_rsqrt();
+  spec2_sqrt_tilde_class = class_new(gensym("spec2_sqrt~"), (t_newmethod)spec2_sqrt_tilde_new,
+    0, sizeof(t_spec2_sqrt_tilde), 0, 0);
+  CLASS_MAINSIGNALIN(spec2_sqrt_tilde_class, t_spec2_sqrt_tilde, x_msi);
+  class_addmethod(spec2_sqrt_tilde_class, (t_method)spec2_sqrt_tilde_dsp, gensym("dsp"), 0);
+  class_sethelpsymbol(spec2_sqrt_tilde_class, gensym("iemhelp2/spec2_sqrt~-help"));
+}