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78 lines
4.0 KiB
C
78 lines
4.0 KiB
C
/***********************************************************************
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Copyright (c) 2006-2012, 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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/* *
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* SKP_Silk_resampler_private_ARMA4.c *
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* *
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* Fourth order ARMA filter, applies 64x gain *
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* *
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* Copyright 2010 (c), Skype Limited *
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* */
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#include "SKP_Silk_SigProc_FIX.h"
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#include "SKP_Silk_resampler_private.h"
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/* Fourth order ARMA filter */
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/* Internally operates as two biquad filters in sequence. */
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/* Coeffients are stored in a packed format: */
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/* { B1_Q14[1], B2_Q14[1], -A1_Q14[1], -A1_Q14[2], -A2_Q14[1], -A2_Q14[2], gain_Q16 } */
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/* where it is assumed that B*_Q14[0], B*_Q14[2], A*_Q14[0] are all 16384 */
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void SKP_Silk_resampler_private_ARMA4(
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SKP_int32 S[], /* I/O: State vector [ 4 ] */
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SKP_int16 out[], /* O: Output signal */
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const SKP_int16 in[], /* I: Input signal */
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const SKP_int16 Coef[], /* I: ARMA coefficients [ 7 ] */
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SKP_int32 len /* I: Signal length */
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)
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{
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SKP_int32 k;
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SKP_int32 in_Q8, out1_Q8, out2_Q8, X;
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for( k = 0; k < len; k++ ) {
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in_Q8 = SKP_LSHIFT32( (SKP_int32)in[ k ], 8 );
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/* Outputs of first and second biquad */
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out1_Q8 = SKP_ADD_LSHIFT32( in_Q8, S[ 0 ], 2 );
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out2_Q8 = SKP_ADD_LSHIFT32( out1_Q8, S[ 2 ], 2 );
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/* Update states, which are stored in Q6. Coefficients are in Q14 here */
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X = SKP_SMLAWB( S[ 1 ], in_Q8, Coef[ 0 ] );
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S[ 0 ] = SKP_SMLAWB( X, out1_Q8, Coef[ 2 ] );
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X = SKP_SMLAWB( S[ 3 ], out1_Q8, Coef[ 1 ] );
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S[ 2 ] = SKP_SMLAWB( X, out2_Q8, Coef[ 4 ] );
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S[ 1 ] = SKP_SMLAWB( SKP_RSHIFT32( in_Q8, 2 ), out1_Q8, Coef[ 3 ] );
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S[ 3 ] = SKP_SMLAWB( SKP_RSHIFT32( out1_Q8, 2 ), out2_Q8, Coef[ 5 ] );
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/* Apply gain and store to output. The coefficient is in Q16 */
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out[ k ] = (SKP_int16)SKP_SAT16( SKP_RSHIFT32( SKP_SMLAWB( 128, out2_Q8, Coef[ 6 ] ), 8 ) );
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}
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}
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