From 386b0b74b0133acb7caddc0f31f5ebbf255efc00 Mon Sep 17 00:00:00 2001
From: Hans-Christoph Steiner <eighthave@users.sourceforge.net>
Date: Tue, 10 Nov 2009 01:47:02 +0000
Subject: split out d_math.c into standalone objects

svn path=/trunk/; revision=12736
---
 externals/vanilla/rsqrt~.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 externals/vanilla/rsqrt~.c

(limited to 'externals/vanilla/rsqrt~.c')

diff --git a/externals/vanilla/rsqrt~.c b/externals/vanilla/rsqrt~.c
new file mode 100644
index 00000000..ce558f5c
--- /dev/null
+++ b/externals/vanilla/rsqrt~.c
@@ -0,0 +1,80 @@
+/* Copyright (c) 1997-2001 Miller Puckette and others.
+* For information on usage and redistribution, and for a DISCLAIMER OF ALL
+* WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */
+
+#include "d_math.h"
+#include "m_pd.h"
+#include <math.h>
+
+/* sigrsqrt - reciprocal square root good to 8 mantissa bits  */
+
+static float rsqrt_exptab[DUMTAB1SIZE], rsqrt_mantissatab[DUMTAB2SIZE];
+
+static void init_rsqrt(void)
+{
+    int i;
+    for (i = 0; i < DUMTAB1SIZE; i++)
+    {
+        float f;
+        int32 l = (i ? (i == DUMTAB1SIZE-1 ? DUMTAB1SIZE-2 : i) : 1)<< 23;
+        *(int32 *)(&f) = l;
+        rsqrt_exptab[i] = 1./sqrt(f);   
+    }
+    for (i = 0; i < DUMTAB2SIZE; i++)
+    {
+        float f = 1 + (1./DUMTAB2SIZE) * i;
+        rsqrt_mantissatab[i] = 1./sqrt(f);      
+    }
+}
+
+typedef struct sigrsqrt
+{
+    t_object x_obj;
+    t_float x_f;
+} t_sigrsqrt;
+
+static t_class *sigrsqrt_class;
+
+static void *sigrsqrt_new(void)
+{
+    t_sigrsqrt *x = (t_sigrsqrt *)pd_new(sigrsqrt_class);
+    outlet_new(&x->x_obj, gensym("signal"));
+    x->x_f = 0;
+    return (x);
+}
+
+static t_int *sigrsqrt_perform(t_int *w)
+{
+    t_sample *in = *(t_sample **)(w+1), *out = *(t_sample **)(w+2);
+    t_int n = *(t_int *)(w+3);
+    while (n--)
+    {   
+        t_sample f = *in;
+        long l = *(long *)(in++);
+        if (f < 0) *out++ = 0;
+        else
+        {
+            t_sample g = rsqrt_exptab[(l >> 23) & 0xff] *
+                rsqrt_mantissatab[(l >> 13) & 0x3ff];
+            *out++ = 1.5 * g - 0.5 * g * g * g * f;
+        }
+    }
+    return (w + 4);
+}
+
+static void sigrsqrt_dsp(t_sigrsqrt *x, t_signal **sp)
+{
+    dsp_add(sigrsqrt_perform, 3, sp[0]->s_vec, sp[1]->s_vec, sp[0]->s_n);
+}
+
+void rsqrt_tilde_setup(void)
+{
+    init_rsqrt();
+    sigrsqrt_class = class_new(gensym("rsqrt~"), (t_newmethod)sigrsqrt_new, 0,
+        sizeof(t_sigrsqrt), 0, 0);
+            /* an old name for it: */
+    class_addcreator(sigrsqrt_new, gensym("q8_rsqrt~"), 0);
+    CLASS_MAINSIGNALIN(sigrsqrt_class, t_sigrsqrt, x_f);
+    class_addmethod(sigrsqrt_class, (t_method)sigrsqrt_dsp, gensym("dsp"), 0);
+}
+
-- 
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