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C++

/*
* Project 25 IMBE Encoder/Decoder Fixed-Point implementation
* Developed by Pavel Yazev E-mail: pyazev@gmail.com
* Version 1.0 (c) Copyright 2009
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* The software 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Boston, MA
* 02110-1301, USA.
*/
#include "typedef.h"
#include "globals.h"
#include "imbe.h"
#include "aux_sub.h"
#include "basic_op.h"
#include "math_sub.h"
#include "pe_lpf.h"
static const Word16 lpf_coef[PE_LPF_ORD] =
{
-94, -92, 185, 543, 288, -883, -1834, -495, 3891, 9141, 11512,
9141, 3891, -495, -1834, -883, 288, 543, 185, -92, -94
};
//-----------------------------------------------------------------------------
// PURPOSE:
// Low-pass filter for pitch estimator
//
//
// INPUT:
// *sigin - pointer to input signal buffer
// *sigout - pointer to output signal buffer
// *mem - pointer to filter's memory element
// len - number of input signal samples
//
// OUTPUT:
// None
//
// RETURN:
// Saved filter state in mem
//
//-----------------------------------------------------------------------------
void pe_lpf(Word16 *sigin, Word16 *sigout, Word16 *mem, Word16 len)
{
Word16 i;
Word32 L_sum;
while(len--)
{
for(i = 0; i < PE_LPF_ORD - 1; i++)
mem[i] = mem[i + 1];
mem[PE_LPF_ORD - 1] = *sigin++;
L_sum = 0;
for(i = 0; i < PE_LPF_ORD; i++)
L_sum = L_mac(L_sum, mem[i], lpf_coef[i]);
*sigout++ = round(L_sum);
}
}