80 lines
4.0 KiB
C
80 lines
4.0 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, (subject to the limitations in the disclaimer below)
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are permitted provided that the following conditions are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Skype Limited, nor the names of specific
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contributors, may be used to endorse or promote products derived from
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this software without specific prior written permission.
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NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#include "SKP_Silk_main_FIX.h"
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void SKP_Silk_LTP_analysis_filter_FIX(
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SKP_int16 *LTP_res, /* O: LTP residual signal of length NB_SUBFR * ( pre_length + subfr_length ) */
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const SKP_int16 *x, /* I: Pointer to input signal with at least max( pitchL ) preceeding samples */
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const SKP_int16 LTPCoef_Q14[ LTP_ORDER * NB_SUBFR ],/* I: LTP_ORDER LTP coefficients for each NB_SUBFR subframe */
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const SKP_int pitchL[ NB_SUBFR ], /* I: Pitch lag, one for each subframe */
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const SKP_int32 invGains_Q16[ NB_SUBFR ], /* I: Inverse quantization gains, one for each subframe */
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const SKP_int subfr_length, /* I: Length of each subframe */
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const SKP_int pre_length /* I: Length of the preceeding samples starting at &x[0] for each subframe */
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)
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{
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const SKP_int16 *x_ptr, *x_lag_ptr;
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SKP_int16 Btmp_Q14[ LTP_ORDER ];
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SKP_int16 *LTP_res_ptr;
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SKP_int k, i, j;
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SKP_int32 LTP_est;
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x_ptr = x;
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LTP_res_ptr = LTP_res;
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for( k = 0; k < NB_SUBFR; k++ ) {
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x_lag_ptr = x_ptr - pitchL[ k ];
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for( i = 0; i < LTP_ORDER; i++ ) {
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Btmp_Q14[ i ] = LTPCoef_Q14[ k * LTP_ORDER + i ];
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}
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/* LTP analysis FIR filter */
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for( i = 0; i < subfr_length + pre_length; i++ ) {
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LTP_res_ptr[ i ] = x_ptr[ i ];
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/* Long-term prediction */
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LTP_est = SKP_SMULBB( x_lag_ptr[ LTP_ORDER / 2 ], Btmp_Q14[ 0 ] );
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for( j = 1; j < LTP_ORDER; j++ ) {
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LTP_est = SKP_SMLABB_ovflw( LTP_est, x_lag_ptr[ LTP_ORDER / 2 - j ], Btmp_Q14[ j ] );
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}
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LTP_est = SKP_RSHIFT_ROUND( LTP_est, 14 ); // round and -> Q0
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/* Subtract long-term prediction */
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LTP_res_ptr[ i ] = ( SKP_int16 )SKP_SAT16( ( SKP_int32 )x_ptr[ i ] - LTP_est );
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/* Scale residual */
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LTP_res_ptr[ i ] = SKP_SMULWB( invGains_Q16[ k ], LTP_res_ptr[ i ] );
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x_lag_ptr++;
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}
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/* Update pointers */
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LTP_res_ptr += subfr_length + pre_length;
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x_ptr += subfr_length;
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}
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}
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