xref: /illumos-gate/usr/src/cmd/audio/include/Fir.h (revision 2a8bcb4e)
1*7c478bd9Sstevel@tonic-gate /*
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14*7c478bd9Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
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21*7c478bd9Sstevel@tonic-gate  */
22*7c478bd9Sstevel@tonic-gate /*
23*7c478bd9Sstevel@tonic-gate  * Copyright (c) 1992-2001 by Sun Microsystems, Inc.
24*7c478bd9Sstevel@tonic-gate  * All rights reserved.
25*7c478bd9Sstevel@tonic-gate  */
26*7c478bd9Sstevel@tonic-gate 
27*7c478bd9Sstevel@tonic-gate #ifndef _MULTIMEDIA_FIR_H
28*7c478bd9Sstevel@tonic-gate #define	_MULTIMEDIA_FIR_H
29*7c478bd9Sstevel@tonic-gate 
30*7c478bd9Sstevel@tonic-gate #ifdef __cplusplus
31*7c478bd9Sstevel@tonic-gate extern "C" {
32*7c478bd9Sstevel@tonic-gate #endif
33*7c478bd9Sstevel@tonic-gate 
34*7c478bd9Sstevel@tonic-gate /*
35*7c478bd9Sstevel@tonic-gate  * Finite Impulse Response (FIR) filter object
36*7c478bd9Sstevel@tonic-gate  *
37*7c478bd9Sstevel@tonic-gate  * For every input sample, the FIR filter generates an output sample:
38*7c478bd9Sstevel@tonic-gate  * output =	coef[0] * input +
39*7c478bd9Sstevel@tonic-gate  *		coef[1] * state[order - 1] +
40*7c478bd9Sstevel@tonic-gate  *		coef[2] * state[order - 2] +
41*7c478bd9Sstevel@tonic-gate  *		...
42*7c478bd9Sstevel@tonic-gate  *		coef[order] * state[0]
43*7c478bd9Sstevel@tonic-gate  *
44*7c478bd9Sstevel@tonic-gate  * and the filter states are updated:
45*7c478bd9Sstevel@tonic-gate  *	state[0] = state[1]
46*7c478bd9Sstevel@tonic-gate  *	state[1] = state[2]
47*7c478bd9Sstevel@tonic-gate  *	...
48*7c478bd9Sstevel@tonic-gate  *	state[order - 2] = state[order - 1]
49*7c478bd9Sstevel@tonic-gate  *	state[order - 1] = input
50*7c478bd9Sstevel@tonic-gate  */
51*7c478bd9Sstevel@tonic-gate class Fir {
52*7c478bd9Sstevel@tonic-gate protected:
53*7c478bd9Sstevel@tonic-gate 	int		order;		// filter order, # taps = order + 1
54*7c478bd9Sstevel@tonic-gate 	double		*coef;		// (order + 1) filter coeffs.
55*7c478bd9Sstevel@tonic-gate 	double		*state;		// "order" filter states
56*7c478bd9Sstevel@tonic-gate 	int		delay;		// actual delay between output & input
57*7c478bd9Sstevel@tonic-gate 
58*7c478bd9Sstevel@tonic-gate 	virtual void	updateState(double *data, int size);
59*7c478bd9Sstevel@tonic-gate 	virtual void	update_short(short *data, int size);
60*7c478bd9Sstevel@tonic-gate 	virtual int	flush(short *out);
61*7c478bd9Sstevel@tonic-gate public:
62*7c478bd9Sstevel@tonic-gate 	virtual void	resetState(void);	// reset states to zero
63*7c478bd9Sstevel@tonic-gate 	Fir(void);
64*7c478bd9Sstevel@tonic-gate 	Fir(int order_in);
65*7c478bd9Sstevel@tonic-gate 	~Fir();
66*7c478bd9Sstevel@tonic-gate 	virtual int	getOrder(void);		// get filter order value
67*7c478bd9Sstevel@tonic-gate 	virtual int	getNumCoefs(void);	// get number of coefficients
68*7c478bd9Sstevel@tonic-gate 	virtual void	putCoef(double *coef_in); // put coef_in in filter coef
69*7c478bd9Sstevel@tonic-gate 	virtual void	getCoef(double *coef_out); // get filter coef
70*7c478bd9Sstevel@tonic-gate 	// filter "size" input samples for "size" output samples
71*7c478bd9Sstevel@tonic-gate 	virtual int	filter_noadjust(short *in, int size, short *out);
72*7c478bd9Sstevel@tonic-gate 	/*
73*7c478bd9Sstevel@tonic-gate 	 * filter "size" input samples. Output sample sequence is offset by
74*7c478bd9Sstevel@tonic-gate 	 * group delay samples to align with the input sample sequence.
75*7c478bd9Sstevel@tonic-gate 	 * the first call of this routine returns "size - group_delay"
76*7c478bd9Sstevel@tonic-gate 	 * output samples. Call this routine with size = 0
77*7c478bd9Sstevel@tonic-gate 	 * to fill the output buffer such that the total number of output
78*7c478bd9Sstevel@tonic-gate 	 * samples is equal to the number of input samples.
79*7c478bd9Sstevel@tonic-gate 	 */
80*7c478bd9Sstevel@tonic-gate 	virtual int	getFlushSize(void); // size of out[] for the last call
81*7c478bd9Sstevel@tonic-gate 	virtual int	filter(short *in, int size, short *out);
82*7c478bd9Sstevel@tonic-gate };
83*7c478bd9Sstevel@tonic-gate 
84*7c478bd9Sstevel@tonic-gate #ifdef __cplusplus
85*7c478bd9Sstevel@tonic-gate }
86*7c478bd9Sstevel@tonic-gate #endif
87*7c478bd9Sstevel@tonic-gate 
88*7c478bd9Sstevel@tonic-gate #endif /* !_MULTIMEDIA_FIR_H */
89