complex_filters.h

00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * complex_filters.h
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2003 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU Lesser General Public License version 2.1,
00014  * as published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  */
00025 
00026 #if !defined(_SPANDSP_COMPLEX_FILTERS_H_)
00027 #define _SPANDSP_COMPLEX_FILTERS_H_
00028 
00029 typedef struct filter_s filter_t;
00030 
00031 typedef float (*filter_step_func_t)(filter_t *fi, float x);
00032 
00033 /*! Filter state */
00034 typedef struct
00035 {
00036     int nz;
00037     int np;
00038     filter_step_func_t fsf;
00039 } fspec_t;
00040 
00041 struct filter_s
00042 {
00043     fspec_t *fs;
00044     float sum;
00045     int ptr;            /* Only for moving average filters */
00046     float v[];
00047 };
00048 
00049 typedef struct
00050 {
00051     filter_t *ref;
00052     filter_t *imf;
00053 } cfilter_t;
00054 
00055 #if defined(__cplusplus)
00056 extern "C"
00057 {
00058 #endif
00059 
00060 SPAN_DECLARE(filter_t *) filter_create(fspec_t *fs);
00061 SPAN_DECLARE(void) filter_delete(filter_t *fi);
00062 SPAN_DECLARE(float) filter_step(filter_t *fi, float x);
00063 
00064 SPAN_DECLARE(cfilter_t *) cfilter_create(fspec_t *fs);
00065 SPAN_DECLARE(void) cfilter_delete(cfilter_t *cfi);
00066 SPAN_DECLARE(complexf_t) cfilter_step(cfilter_t *cfi, const complexf_t *z);
00067 
00068 #if defined(__cplusplus)
00069 }
00070 #endif
00071 
00072 #endif
00073 /*- End of file ------------------------------------------------------------*/

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