From 8a4bca986c57062e96f1e58281b3eff52a856ee6 Mon Sep 17 00:00:00 2001
From: rekado <rekado@elephly.net>
Date: Tue, 6 Sep 2016 22:13:03 +0200
Subject: Initial commit.

---
 objects/faust/karplus.axo | 98 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 objects/faust/karplus.axo

(limited to 'objects/faust/karplus.axo')

diff --git a/objects/faust/karplus.axo b/objects/faust/karplus.axo
new file mode 100644
index 0000000..60035a6
--- /dev/null
+++ b/objects/faust/karplus.axo
@@ -0,0 +1,98 @@
+<objdefs>
+   <obj.normal id="karplus" uuid="36d552a0297885559841ed95a25ec5e5589bf5c3" sha="39267e0b01468fb54a8799d8114d535c594a007b">
+   <sDescription>Karplus (from Faust)</sDescription>
+      <author>Ricardo Wurmus</author>
+      <license>GPL</license>
+      <helpPatch>filter.axh</helpPatch>
+      <outlets>
+         <frac32buffer.bipolar name="out" description="filter output"/>
+      </outlets>
+      <params>
+         <bool32.mom name="b" noLabel="true"/>
+         <frac32.s.map name="a"/>
+      </params>
+      <displays/>
+      <includes>
+        <include>arm_math.h</include>
+      </includes>
+      <attribs/>
+      <code.declaration><![CDATA[
+            // convert float to fixed point notation
+            // * take absolute value
+            // * multiply with constant to keep precision;
+            //   to get a fixed point at x:y we multiply by 2^y,
+            //   e.g. for 24:8 (24 significant bits before decimal point)
+            //   we multiply f by 2^8 (1<<8).
+            // * truncate and cast to int32_t
+            // * invert bits if negative
+            int32_t floatToFrac32(float f) {
+              // was 1 000 000 000 and then >> 2
+              // now is 2^27 = 134 217 728
+              // 2^32 = 4 294 967 296
+              // 2^29 = 536 870 912 (3:29)
+              int32_t preout = int32_t(((f < 0) ? (-f) : f) * (1<<29));
+              return ((f < 0) ? ~preout : preout);
+            }
+            // convert fixed point to float
+            // * invert bits if sign bit is set (0x08000000, or (1<<27))
+            // * cast int to float
+            // * divide by constant to shift decimal point
+            // * multiply by -1 if sign bit was set
+            float frac32ToFloat(int32_t frac) {
+              bool neg = (((1<<27) & frac) != 0);
+              float res = (float)(neg ? frac : ~frac);
+              res = res / (float(1<<29));
+              return (neg ? (-1 * res) : res);
+            }
+
+	float 	fslider0;
+	float 	fVec0[2];
+	float 	fRec1[2];
+	int 	iRec2[2];
+	float 	fslider1;
+	float 	fslider2;
+	int 	IOTA;
+	float 	fVec1[512];
+	float 	fslider3;
+	float 	fRec0[3];
+]]></code.declaration>
+      <code.init><![CDATA[
+		fslider0 = 128.0f; // duration or excitation
+		for (int i=0; i<2; i++) fVec0[i] = 0;
+		for (int i=0; i<2; i++) fRec1[i] = 0;
+		for (int i=0; i<2; i++) iRec2[i] = 0;
+		fslider1 = 0.5f; // level
+		fslider2 = 0.01f; // attenuation, was 0.1f
+		IOTA = 0;
+		for (int i=0; i<512; i++) fVec1[i] = 0;
+		fslider3 = 128.0f; // duration or excitation
+		for (int i=0; i<3; i++) fRec0[i] = 0;
+]]></code.init>
+      <code.krate><![CDATA[
+		float 	fSlow0 = (1.0f / float(fslider0));
+		float 	fSlow1 = float(param_b);
+		float 	fSlow2 = (4.656612875245797e-10f * float(fslider1));
+		float 	fSlow3 = (0.5f * (1.0f - float(fslider2)));
+		int 	iSlow4 = int((int((float(fslider3) - 1.5f)) & 4095));
+
+        int32_t* output0 = outlet_out;
+		for (int i=0; i<BUFSIZE; i++) {
+			fVec0[0] = fSlow1;
+			fRec1[0] = ((fRec1[1] + ((fSlow1 - fVec0[1]) > 0.0f)) - (fSlow0 * (fRec1[1] > 0.0f)));
+			iRec2[0] = (12345 + (1103515245 * iRec2[1]));
+			fVec1[IOTA&511] = ((fSlow3 * (fRec0[1] + fRec0[2])) + (fSlow2 * (iRec2[0] * (fRec1[0] > 0.0f))));
+			fRec0[0] = fVec1[(IOTA-iSlow4)&511];
+
+arm_float_to_q31(&fRec0[0], &output0[i], 0);
+//   			output0[i] = floatToFrac32(fRec0[0]);
+            
+			// post processing
+			fRec0[2] = fRec0[1]; fRec0[1] = fRec0[0];
+			IOTA = IOTA+1;
+			iRec2[1] = iRec2[0];
+			fRec1[1] = fRec1[0];
+			fVec0[1] = fVec0[0];
+		}
+]]></code.krate>
+   </obj.normal>
+</objdefs>
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