kopia lustrzana https://github.com/Dsplib/libdspl-2.0
188 wiersze
3.9 KiB
C
188 wiersze
3.9 KiB
C
/*
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* Copyright (c) 2015-2019 Sergey Bakhurin
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* Digital Signal Processing Library [http://dsplib.org]
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*
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* This file is part of libdspl-2.0.
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*
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* is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* DSPL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "dspl.h"
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#include "dspl_internal.h"
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/******************************************************************************
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Farrow resampler based on the cubic Lagrange polynomials
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*******************************************************************************/
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int DSPL_API farrow_lagrange(double *s, int n, double p, double q,
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double frd, double **y, int *ny)
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{
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double a[4];
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double t, x, dt;
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int ind, k, res;
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double g[4];
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double *z;
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if(!s || !y)
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return ERROR_PTR;
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if(n<1)
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return ERROR_SIZE;
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if(p <= 0.0 || q <= 0.0)
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return ERROR_RESAMPLE_RATIO;
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if(frd <= -1.0 || frd >= 1.0)
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return ERROR_RESAMPLE_FRAC_DELAY;
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dt = q/p;
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if((*ny) != (int)((double)(n-1)/dt)+1 || !(*y))
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{
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*ny = (int)((double)(n-1)/dt)+1;
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(*y) = (double*)realloc((*y), (*ny)*sizeof(double));
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}
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t = -frd;
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k = 0;
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while(k < (*ny))
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{
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ind = (int)floor(t)+1;
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x = t - (double)ind;
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ind-=2;
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if(ind < 0)
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{
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memset(g, 0, 4*sizeof(double));
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if(ind > (-3))
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memcpy(g-ind, s, (4+ind)*sizeof(double));
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z = g;
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}
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else
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{
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if(ind < n-3)
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z = s+ind;
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else
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{
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memset(g, 0, 4*sizeof(double));
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if((n-ind)>0)
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memcpy(g, s+ind, (n-ind)*sizeof(double));
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z = g;
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}
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}
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a[0] = z[2];
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a[3] = DSPL_FARROW_LAGRANGE_COEFF*(z[3] -z[0]) + 0.5*(z[1] - z[2]);
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a[1] = 0.5*(z[3] - z[1])-a[3];
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a[2] = z[3] - z[2] -a[3]-a[1];
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res = polyval(a, 3, &x, 1, (*y)+k);
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if(res != RES_OK)
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goto exit_label;
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t+=dt;
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k++;
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}
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exit_label:
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return res;
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}
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/******************************************************************************
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Farrow resampler based on the cubic splines
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*******************************************************************************/
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int DSPL_API farrow_spline(double *s, int n, double p, double q,
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double frd, double **y, int *ny)
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{
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double a[4];
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double t, x, dt;
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int ind, k, res;
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double g[4];
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double *z;
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if(!s || !y)
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return ERROR_PTR;
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if(n<1)
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return ERROR_SIZE;
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if(p <= 0.0 || q <= 0.0)
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return ERROR_RESAMPLE_RATIO;
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if(frd <= -1.0 || frd >= 1.0)
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return ERROR_RESAMPLE_FRAC_DELAY;
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dt = q/p;
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if((*ny) != (int)((double)(n-1)/dt)+1 || !(*y))
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{
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*ny = (int)((double)(n-1)/dt)+1;
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(*y) = (double*)realloc((*y), (*ny)*sizeof(double));
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}
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t = -frd;
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k = 0;
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while(k < (*ny))
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{
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ind = (int)floor(t)+1;
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x = t - (double)ind;
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ind-=2;
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if(ind < 0)
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{
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memset(g, 0, 4*sizeof(double));
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if(ind > (-3))
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memcpy(g-ind, s, (4+ind)*sizeof(double));
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z = g;
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}
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else
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{
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if(ind < n-3)
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z = s+ind;
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else
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{
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memset(g, 0, 4*sizeof(double));
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if((n-ind)>0)
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memcpy(g, s+ind, (n-ind)*sizeof(double));
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z = g;
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}
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}
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a[0] = z[2];
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a[1] = 0.5*(z[3] - z[1]);
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a[3] = 2.0*(z[1] - z[2]) + a[1] + 0.5*(z[2] - z[0]);
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a[2] = z[1] - z[2] +a[3] + a[1];
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res = polyval(a, 3, &x, 1, (*y)+k);
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if(res != RES_OK)
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goto exit_label;
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t+=dt;
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k++;
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}
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exit_label:
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return res;
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}
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