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/*=============================================================================
*
* This software has been released under the terms of the GNU Public
* license. See http://www.gnu.org/copyleft/gpl.html for details.
*
* Copyright 2001 Anders Johansson ajh@atri.curtin.edu.au
*
*=============================================================================
*/
#if !defined _DSP_H
# error "Never use <filter.h> directly; include <dsp.h> instead"
#endif
#ifndef _FILTER_H
#define _FILTER_H 1
/* Design and implementation of different types of digital filters */
/* Flags used for filter design */
/* Filter characteristics */
#define LP 0x00010000 /* Low pass */
#define HP 0x00020000 /* High pass */
#define BP 0x00040000 /* Band pass */
#define BS 0x00080000 /* Band stop */
#define TYPE_MASK 0x000F0000
/* Window types */
#define BOXCAR 0x00000001
#define TRIANG 0x00000002
#define HAMMING 0x00000004
#define HANNING 0x00000008
#define BLACKMAN 0x00000010
#define FLATTOP 0x00000011
#define KAISER 0x00000012
#define WINDOW_MASK 0x0000001F
/* Parallel filter design */
#define FWD 0x00000001 /* Forward indexing of polyphase filter */
#define REW 0x00000002 /* Reverse indexing of polyphase filter */
#define ODD 0x00000010 /* Make filter HP */
/* Exported functions */
extern _ftype_t fir(unsigned int n, _ftype_t* w, _ftype_t* x);
extern _ftype_t* pfir(unsigned int n, unsigned int k, unsigned int xi, _ftype_t** w, _ftype_t** x, _ftype_t* y, unsigned int s);
extern int updateq(unsigned int n, unsigned int xi, _ftype_t* xq, _ftype_t* in);
extern int updatepq(unsigned int n, unsigned int k, unsigned int xi, _ftype_t** xq, _ftype_t* in, unsigned int s);
extern int design_fir(unsigned int n, _ftype_t* w, _ftype_t* fc, unsigned int flags, _ftype_t opt);
extern int design_pfir(unsigned int n, unsigned int k, _ftype_t* w, _ftype_t** pw, _ftype_t g, unsigned int flags);
extern void prewarp(_ftype_t* a, _ftype_t fc, _ftype_t fs);
void bilinear(_ftype_t* a, _ftype_t* b, _ftype_t* k, _ftype_t fs, _ftype_t *coef);
extern int szxform(const _ftype_t* a, const _ftype_t* b, _ftype_t Q, _ftype_t fc, _ftype_t fs, _ftype_t *k, _ftype_t *coef);
/* Add new data to circular queue designed to be used with a FIR
* filter. xq is the circular queue, in pointing at the new sample, xi
* current index for xq and n the length of the filter. xq must be n*2
* long.
*/
#define updateq(n,xi,xq,in)\
xq[xi]=(xq)[(xi)+(n)]=*(in);\
xi=(++(xi))&((n)-1);
#endif
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