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/**
* Smarc
*
* Copyright (c) 2009-2011 Institut Télécom - Télécom Paristech
* Télécom ParisTech / dept. TSI
*
* Authors : Benoit Mathieu, Jacques Prado
*
* This file is part of Smarc.
*
* Smarc is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Smarc is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "stage_impl.h"
#include "filtering.h"
#include "polyfilt.h"
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include "remez_lp.h"
#define MAX_FILTER_LENGTH 8192
void build_filter(double fpass, double fstop,
double rp, double rs, int rpFactor, double** h, int* len, int lenStep) {
int i;
double *bands, *mag, *dev, *weight;
// printf("build filter %f %f %f, %f/%i %f (lenstep=%i)\n",fpass,fstop,fmax,rp,rpFactor, rs,lenStep);
bands = malloc(10 * sizeof(double));
mag = &bands[4];
dev = &mag[2];
weight = &dev[2];
bands[0] = 0;
bands[1] = fpass;
bands[2] = fstop;
bands[3] = 0.5;
mag[0] = 1;
mag[1] = 0;
dev[0] = (pow(10, rp / 20.0) - 1) / (rpFactor *(pow(10, rp / 20.0) + 1));
dev[1] = pow(10, -rs / 20.0);
int n = remez_lp_order(bands, mag, dev, weight);
// filter length must be 2*K*lenStep+1 so that delay is integer
{
int k = 1;
while (2*k*lenStep + 1 < n)
k++;
*len = 2*k*lenStep + 1;
}
if (n>MAX_FILTER_LENGTH)
{
free(bands);
*len = 0;
printf("ERROR: cannot build remez filter, it's too long ! (%i) try with other parameters\n",n);
return;
}
*h = malloc((*len) * sizeof(double));
for (i = 0; i < *len; i++)
(*h)[i] = 0;
int iRc = remez_lp(*h, *len, bands, mag, weight);
if (iRc)
{
free(*h);
*h = NULL;
*len = 0;
}
free(bands);
}
struct PSFilter* init_psfilter(int L, int M,
double fpass, double fstop,
double rp, double rs, int rpFactor) {
double* h = 0;
int Lenh;
build_filter(fpass,fstop,rp, rs, rpFactor, &h, &Lenh,M);
if (Lenh==0)
{
printf("ERROR: cannot build filter %i/%i (within a %i stage filter) with parameters fpass=%0.2f fstop=%0.2f rp=%0.2f rs=%0.2f\n",L,M,rpFactor, fpass,fstop,rp,rs);
return NULL;
}
// ensure Lenh > M+L-1
// (this is generally already true, but must check it for polyfiltLM)
while (Lenh<(L+M-1))
Lenh += 2 * M;
struct PSFilter* pfilt = malloc(sizeof(struct PSFilter));
// adjust filter gain
if (L>1)
for (int i = 0; i < Lenh; i++)
h[i] *= L;
// filters
int K = Lenh / L;
if (Lenh > K*L)
K++;
pfilt->filters = malloc(L*K*sizeof(double));
if (L==1)
{
// decimation filter (only one filter)
for (int k=0;k<K;k++)
pfilt->filters[K-1-k] = h[k];
} else {
// filter with interpolation (one filter per interpolation tap)
for (int i=0;i<L;i++)
pfilt->filters[i*K] = 0.0;
for (int i=0;i<Lenh;i++)
{
pfilt->filters[(i%L)*K+K-1-i/L] = h[i];
}
}
free(h);
pfilt->flen = Lenh;
pfilt->M = M;
pfilt->L = L;
pfilt->K = K;
pfilt->filter_delay = (Lenh - 1) / (2*M);
return pfilt;
}
void destroy_psfilter(struct PSFilter* pfilt) {
free(pfilt->filters);
free(pfilt);
}
struct PSState* init_psstate(struct PSFilter* pfilt) {
struct PSState* pstate = (struct PSState*) malloc(sizeof(struct PSState));
pstate->skip = 0;
pstate->phase = 0;
reset_psstate(pstate,pfilt);
return pstate;
}
void destroy_psstate(struct PSState* pstate) {
free(pstate);
}
void reset_psstate(struct PSState* pstate, const struct PSFilter* pfilt) {
pstate->skip=pfilt->filter_delay;
pstate->phase = 0;
}
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