%/******************************************************************************\
% * Copyright (c) 2004-2006
% *
% * Author(s):
% *	Volker Fischer
% *
%\******************************************************************************/

function resamplefilter()

% Number of taps per poly phase for different resampling types
NoTapsP2   = 12;
NoTapsP3_2 = 12;
NoTapsP1   = 12;


% Filter for ratio 2 -----------------------------------------------------------
% I and D
I2 = 2;
D2 = 1;

% filter design
h2 = DesignFilter(NoTapsP2, I2);


% Filter for ratio 3 / 2 -------------------------------------------------------
% I and D
I3_2 = 3;
D3_2 = 2;

% filter design
h3_2 = DesignFilter(NoTapsP3_2, I3_2);


% Filter for ratios close to 1 -------------------------------------------------
% Fixed for sample-rate conversiones of R ~ 1
I1 = 10; % D = I in this mode

% MMSE filter-design and windowing
h1 = DesignFilter(NoTapsP1, I1);


% Export coefficiants to file ****************************************
fid = fopen('resamplefilter.h', 'w');

fprintf(fid, '/* Automatically generated file with MATLAB */\n');
fprintf(fid, '/* File name: "ResampleFilter.m" */\n');
fprintf(fid, '/* Filter taps in time-domain */\n\n');

fprintf(fid, '#ifndef _RESAMPLEFILTER_H_\n');
fprintf(fid, '#define _RESAMPLEFILTER_H_\n\n');

fprintf(fid, '#define NUM_TAPS_PER_PHASE2          ');
fprintf(fid, int2str(NoTapsP2));
fprintf(fid, '\n');
fprintf(fid, '#define NUM_TAPS_PER_PHASE3_2        ');
fprintf(fid, int2str(NoTapsP3_2));
fprintf(fid, '\n');
fprintf(fid, '#define NUM_TAPS_PER_PHASE1          ');
fprintf(fid, int2str(NoTapsP1));
fprintf(fid, '\n');
fprintf(fid, '#define INTERP_I_2                   ');
fprintf(fid, int2str(I2));
fprintf(fid, '\n');
fprintf(fid, '#define DECIM_D_2                    ');
fprintf(fid, int2str(D2));
fprintf(fid, '\n');
fprintf(fid, '#define INTERP_I_3_2                 ');
fprintf(fid, int2str(I3_2));
fprintf(fid, '\n');
fprintf(fid, '#define DECIM_D_3_2                  ');
fprintf(fid, int2str(D3_2));
fprintf(fid, '\n');
fprintf(fid, '#define INTERP_DECIM_I_D1            ');
fprintf(fid, int2str(I1));
fprintf(fid, '\n');
fprintf(fid, '\n\n');

% Write filter taps
fprintf(fid, '\n// Filter for ratio 2\n');
ExportFilterTaps(fid, 'fResTaps2[INTERP_I_2 * DECIM_D_2 * NUM_TAPS_PER_PHASE2]', h2);

fprintf(fid, '\n// Filter for ratio 3 / 2\n');
ExportFilterTaps(fid, 'fResTaps3_2[INTERP_I_3_2 * DECIM_D_3_2 * NUM_TAPS_PER_PHASE3_2]', h3_2);

fprintf(fid, '// Filter for ratios close to 1\n');
ExportFilterTaps(fid, 'fResTaps1[INTERP_DECIM_I_D1 * NUM_TAPS_PER_PHASE1]', h1);

fprintf(fid, '\n#endif	/* _RESAMPLEFILTER_H_ */\n');
fclose(fid);

return;


function [h] = DesignFilter(NoTapsPIn, I)

% number of taps, consider interpolation factor
NoTapsP = NoTapsPIn * I;

% Cut-off frequency (normlized)
fc = 0.97 / I;

% MMSE filter design with Kaiser window, consider interpolation factor
h = I * firls(NoTapsP - 1, [0 fc fc 1], [1 1 0 0]) .* kaiser(NoTapsP, 5)';

return;


function ExportFilterTaps(f, name, h)

% Write filter taps
fprintf(f, ['static float ' name ' = {\n']);
fprintf(f, '	%.20ff,\n', h(1:end - 1));
fprintf(f, '	%.20ff\n', h(end));
fprintf(f, '};\n\n');

return;