From f4e27be46c01e60acfe97ae020e036581c4cab77 Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Sat, 25 Oct 2025 15:05:44 +0200
Subject: [PATCH] delete redundant Iir

---
 src/Iir.c | 225 ------------------------------------------------------
 src/Iir.h |  68 -----------------
 2 files changed, 293 deletions(-)
 delete mode 100755 src/Iir.c
 delete mode 100755 src/Iir.h

diff --git a/src/Iir.c b/src/Iir.c
deleted file mode 100755
index 87980e1..0000000
--- a/src/Iir.c
+++ /dev/null
@@ -1,225 +0,0 @@
-/*************************************************************************/
-/* iir.c
-/*************************************************************************/
-#include "stdio.h"
-#include "math.h"
-#include "iir.h"
-
-/*************************************************************************/
-/* Global Variables
-/*************************************************************************/
-const char *filterTypeString[] =
-{
-	"Unknown filter type",
-	"Butterworth-Lowpass",
-	"Butterworth-Highpass",
-    "Butterworth-Bandpass",
-	"Butterworth-Bandstop",
-	"Peaking-EQ",
-	"Low Shelving-EQ",
-	"High Shelving-EQ"
-};
-
-/******************************************************************************/
-void IIRCalcFilterCoeff(struct _sIIRCoeff *pCoeff, float fa, float fg, float q, unsigned order, unsigned filterType)
-{
-	unsigned p;
-	float qp;
-	
-	//IIRInit(pCoeff, order);
-
-	for(p=0; p < order/2;p++)
-	{
-		qp = q * IIRCalcQp(p+1, order);
-		IIRCalcPartFilterCoeff2(&pCoeff[p], 1.0, fa, fg, qp, filterType);
-	}
-}
-
-int IIRCalcPartFilterCoeff1(struct _sIIRCoeff *pCoeff, float fa, float fg, float Qi, unsigned filterType)
-{
-	float K, a0;
-	float alpha, omega, ks, kc;
-	unsigned error;
-
-	omega = (float)(2*pi*fg/fa);
-	ks    = (float)sin(omega);
-	kc    = (float)cos(omega);
-	alpha = (float)(0.5*ks /Qi);
-
-	K  = IIRBilTrans(fg, fa);
-	a0 = K/Qi + 1;
-
-	switch(filterType)
-	{
-	case IIR_FILTERTYPE_LOWPASS:
-	
-		pCoeff->ak0 = 1.0;
-		pCoeff->ak1 = (1 - K/Qi)/a0;
-		pCoeff->ak2 = 0.0;
-
-		pCoeff->bk0 = (float)(1.0/a0);
-		pCoeff->bk1 = (float)(1.0/a0);
-		pCoeff->bk2 = (float)0.0;
-
-		break;
-	
-	case IIR_FILTERTYPE_HIGHPASS:
-	
-		pCoeff->ak0 = 1.0;
-		pCoeff->ak1 = (1 - K/Qi) /a0;
-		pCoeff->ak2 = 0.0;
-
-		pCoeff->bk0 =  (float)(1.0*K /a0);
-		pCoeff->bk1 = (float)(-1.0*K /a0);
-		pCoeff->bk2 =  (float)0.0;
-		
-		break;
-
-	default:
-		error = -1;
-		break;
-	}
-	return error;
-}
-
-int IIRCalcPartFilterCoeff2(struct _sIIRCoeff *pCoeff, float A, float fa, float fg, float qp, unsigned filterType)
-{
-	float a0;
-	float alpha, omega, ks, kc;
-	unsigned error;
-
-	omega = (float)(2*pi*fg/fa);
-	ks    = (float)sin(omega);
-	kc    = (float)cos(omega);
-	alpha = (float)(0.5*ks /qp);
-
-	error = 0;
-	switch(filterType)
-	{
-	case IIR_FILTERTYPE_LOWPASS:
-
-		a0 = 1 + alpha;
-		pCoeff->ak0 =  1.0;
-		pCoeff->ak1 = (float)(-2.0*kc /a0);
-		pCoeff->ak2 = (1 - alpha) /a0;
-
-		pCoeff->bk0 = (float)(0.5*(1 - kc) /a0);
-		pCoeff->bk1 = (1 - kc) /a0;
-		pCoeff->bk2 = (float)(0.5*(1 - kc) /a0);
-
-		break;
-	
-	case IIR_FILTERTYPE_HIGHPASS:
-
-		a0 = 1 + alpha;
-		pCoeff->ak0 =  1.0;
-		pCoeff->ak1 = (float)(-2.0*kc /a0);
-		pCoeff->ak2 = (1 - alpha) /a0;
-
-		pCoeff->bk0 = (float)(0.5*(1 + kc) /a0);
-		pCoeff->bk1 = -(1 + kc) /a0;
-		pCoeff->bk2 = (float)(0.5*(1 + kc) /a0);
-
-		break;
-
-	case IIR_FILTERTYPE_BANDPASS:
-
-		a0 = 1 + alpha;
-		pCoeff->ak0 =  1.0;
-		pCoeff->ak1 = (float)(-2.0*kc /a0);
-		pCoeff->ak2 = (1 - alpha) /a0;
-
-		pCoeff->bk0 = alpha /a0;
-		pCoeff->bk1 = 0;
-		pCoeff->bk2 = -alpha /a0;
-
-		break;
-
-	case IIR_FILTERTYPE_BANDSTOP:
-
-		a0 = 1 + alpha;
-		pCoeff->ak0 =  1.0;
-		pCoeff->ak1 = (float)(-2.0*kc /a0);
-		pCoeff->ak2 = (1 - alpha) /a0;
-
-		pCoeff->bk0 = (float)(1.0 /a0);
-		pCoeff->bk1 = (float)(-2.0*kc /a0);
-		pCoeff->bk2 = (float)(1.0 /a0);
-
-		break;
-
-	case IIR_FILTERTYPE_PEAKING:
-
-		a0 = 1 + (alpha/A);
-		pCoeff->ak0 =  1.0;
-		pCoeff->ak1 = (float)(-2.0*kc /a0);
-		pCoeff->ak2 = (1 - (alpha/A)) /a0;
-
-		pCoeff->bk0 =  (1 + (alpha*A)) /a0;
-		pCoeff->bk1 = (float)(-2.0*kc /a0);
-		pCoeff->bk2 =  (1 - (alpha*A)) /a0;
-
-		break;
-
-	default:
-		error = -1;
-		break;
-	}
-	return error;
-}
-
-void IIR(struct _sIIRCoeff *pCoeff, float *xn, float *yn, unsigned order, unsigned numPoints)
-{
-	float xp, yp;
-	unsigned i, p;
-	unsigned numSec = order/2;
-
-	for (i=0; i<numPoints; i++)
-	{
-		xp = xn[i];
-		for (p=0; p < numSec; p++)
-		{
-			yp = pCoeff[p].bk0*xp 
-			   + pCoeff[p].bk1*pCoeff[p].xn1
-			   + pCoeff[p].bk2*pCoeff[p].xn2
-			   - pCoeff[p].ak1*pCoeff[p].yn1
-			   - pCoeff[p].ak2*pCoeff[p].yn2;
-			
-			pCoeff[p].yn2 = pCoeff[p].yn1;
-			pCoeff[p].yn1 = yp;
-			pCoeff[p].xn2 = pCoeff[p].xn1;
-			pCoeff[p].xn1 = xp;
-			xp	  = yp;
-		}
-		yn[i] = yp;	
-	}
-}
-
-void IIRInit(struct _sIIRCoeff *pCoeff, unsigned order)
-{
-	unsigned n;
-	for(n=0; n < order/2; n++)
-	{
-		pCoeff[n].ak0 = 0;
-		pCoeff[n].ak1 = 0;
-		pCoeff[n].ak2 = 0;
-		pCoeff[n].bk0 = 0;
-		pCoeff[n].bk1 = 0;
-		pCoeff[n].bk2 = 0;
-		pCoeff[n].xn1 = 0;
-		pCoeff[n].xn2 = 0;
-		pCoeff[n].yn1 = 0;
-		pCoeff[n].yn2 = 0;
-	}
-}
-
-float IIRBilTrans(float fg, float fa)
-{
-	return (float)(1.0/(tan(pi*fg/fa)));
-}
-
-float IIRCalcQp(unsigned p, unsigned N)
-{
-	return (float)(1.0/(2*sin(pi*(2*p-1)/(2*N))));
-}
-
diff --git a/src/Iir.h b/src/Iir.h
deleted file mode 100755
index 0cb20e7..0000000
--- a/src/Iir.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/******************************************************************************/
-/* iir.h
-/******************************************************************************/
-#ifndef IIR_H
-#define IIR_H
-
-#define	pi			3.1415926535897932384626433832795
-
-#define IIR_FILTERTYPE_UNKNOWN     0x00000000
-#define IIR_FILTERTYPE_LOWPASS     0x00000001
-#define IIR_FILTERTYPE_HIGHPASS    0x00000002
-#define IIR_FILTERTYPE_BANDPASS    0x00000003
-#define IIR_FILTERTYPE_BANDSTOP    0x00000004
-#define IIR_FILTERTYPE_PEAKING     0x00000005
-#define IIR_FILTERTYPE_LOWSHELF    0x00000006
-#define IIR_FILTERTYPE_HIGHSHELF   0x00000007
-
-#if defined(__cplusplus)
-extern "C" {
-#endif
-/******************************************************************************/
-typedef struct _sComplex
-{
-	float pRealData, pImagData;
-} Complex;
-
-typedef struct _sIIRCoeff
-{
-
-	float ak0, ak1, ak2;
-	float bk0, bk1, bk2;
-	float xn1, xn2;
-	float yn1, yn2;
-
-}IIRCOEFF;
-
-typedef struct _sIIRParam
-{
-	/* General Params */
-	float fg, Qf;
-	
-	/* for shelving EQs */
-	float beta; 
- 
-	/* for peaking and shelving EQs */
-	float A;
-}IIRPARAM;
-
-/******************************************************************************/
-void IIRInit(struct _sIIRCoeff *pCoeff, unsigned order);
-int IIRCalcPartFilterCoeff1(struct _sIIRCoeff *pCoeff, float fa, float fg, float qp, unsigned filterType);
-int IIRCalcPartFilterCoeff2(struct _sIIRCoeff *pCoeff, float A, float fa, float fg, float qp, unsigned filterType);
-void IIRCalcFilterCoeff(struct _sIIRCoeff *pCoeff, float fa, float fg, float q, unsigned order, unsigned filterType);
-
-float IIRBilTrans(float fg, float fa);
-float IIRCalcQp(unsigned p, unsigned N);
-void IIR(struct _sIIRCoeff *pCoeff, float *xn, float *yn, unsigned order, unsigned numPoints);
-void IIRPrintCoeff(FILE *pFile, struct _sIIRCoeff *pCoeff, unsigned N);
-void ScaleCoeff(struct _sIIRCoeff *pCoeff);
-float MinMag(float val1, float val2);
-float MaxMag(float val1, float val2);
-
-/******************************************************************************/
-#if defined(__cplusplus)
-}
-#endif
-
-#endif /* IIR_H */