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79 lines
2.4 KiB
79 lines
2.4 KiB
/*
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* Project 25 IMBE Encoder/Decoder Fixed-Point implementation
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* Developed by Pavel Yazev E-mail: pyazev@gmail.com
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* Version 1.0 (c) Copyright 2009
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* The software is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this; see the file COPYING. If not, write to the Free
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* Software Foundation, Inc., 51 Franklin Street, Boston, MA
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* 02110-1301, USA.
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*/
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#include "imbe/typedef.h"
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#include "imbe/globals.h"
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#include "imbe/imbe.h"
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#include "imbe/aux_sub.h"
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#include "imbe/basic_op.h"
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#include "imbe/math_sub.h"
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#include "imbe/pe_lpf.h"
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// ---------------------------------------------------------------------------
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// Constants
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// ---------------------------------------------------------------------------
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static const Word16 lpf_coef[PE_LPF_ORD] =
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{
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-94, -92, 185, 543, 288, -883, -1834, -495, 3891, 9141, 11512,
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9141, 3891, -495, -1834, -883, 288, 543, 185, -92, -94
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};
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// ---------------------------------------------------------------------------
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// Global Functions
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// ---------------------------------------------------------------------------
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//-----------------------------------------------------------------------------
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// PURPOSE:
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// Low-pass filter for pitch estimator
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//
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//
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// INPUT:
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// *sigin - pointer to input signal buffer
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// *sigout - pointer to output signal buffer
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// *mem - pointer to filter's memory element
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// len - number of input signal samples
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//
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// OUTPUT:
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// None
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//
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// RETURN:
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// Saved filter state in mem
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//
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//-----------------------------------------------------------------------------
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void pe_lpf(Word16* sigin, Word16* sigout, Word16* mem, Word16 len)
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{
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Word16 i;
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Word32 L_sum;
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while (len--) {
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for (i = 0; i < PE_LPF_ORD - 1; i++)
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mem[i] = mem[i + 1];
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mem[PE_LPF_ORD - 1] = *sigin++;
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L_sum = 0;
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for (i = 0; i < PE_LPF_ORD; i++)
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L_sum = L_mac(L_sum, mem[i], lpf_coef[i]);
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*sigout++ = L_round(L_sum);
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}
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}
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