116 lines
5.4 KiB
C
116 lines
5.4 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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/* *
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* SKP_Silk_MA.c *
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* *
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* Variable order MA filter *
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* *
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* Copyright 2006 (c), Skype Limited *
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* Date: 060221 *
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* */
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#include "SKP_Silk_SigProc_FIX.h"
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/* Variable order MA prediction error filter */
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void SKP_Silk_MA_Prediction(
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const SKP_int16 *in, /* I: Input signal */
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const SKP_int16 *B, /* I: MA prediction coefficients, Q12 [order] */
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SKP_int32 *S, /* I/O: State vector [order] */
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SKP_int16 *out, /* O: Output signal */
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const SKP_int32 len, /* I: Signal length */
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const SKP_int32 order /* I: Filter order */
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)
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{
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SKP_int k, d, in16;
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SKP_int32 out32;
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for( k = 0; k < len; k++ ) {
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in16 = in[ k ];
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out32 = SKP_LSHIFT( in16, 12 ) - S[ 0 ];
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out32 = SKP_RSHIFT_ROUND( out32, 12 );
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for( d = 0; d < order - 1; d++ ) {
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S[ d ] = SKP_SMLABB_ovflw( S[ d + 1 ], in16, B[ d ] );
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}
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S[ order - 1 ] = SKP_SMULBB( in16, B[ order - 1 ] );
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/* Limit */
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out[ k ] = (SKP_int16)SKP_SAT16( out32 );
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}
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}
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void SKP_Silk_LPC_analysis_filter(
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const SKP_int16 *in, /* I: Input signal */
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const SKP_int16 *B, /* I: MA prediction coefficients, Q12 [order] */
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SKP_int16 *S, /* I/O: State vector [order] */
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SKP_int16 *out, /* O: Output signal */
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const SKP_int32 len, /* I: Signal length */
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const SKP_int32 Order /* I: Filter order */
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)
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{
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SKP_int k, j, idx, Order_half = SKP_RSHIFT( Order, 1 );
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SKP_int32 out32_Q12, out32;
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SKP_int16 SA, SB;
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/* Order must be even */
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SKP_assert( 2 * Order_half == Order );
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/* S[] values are in Q0 */
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for( k = 0; k < len; k++ ) {
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SA = S[ 0 ];
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out32_Q12 = 0;
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for( j = 0; j < ( Order_half - 1 ); j++ ) {
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idx = SKP_SMULBB( 2, j ) + 1;
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/* Multiply-add two prediction coefficients for each loop */
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SB = S[ idx ];
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S[ idx ] = SA;
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out32_Q12 = SKP_SMLABB( out32_Q12, SA, B[ idx - 1 ] );
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out32_Q12 = SKP_SMLABB( out32_Q12, SB, B[ idx ] );
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SA = S[ idx + 1 ];
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S[ idx + 1 ] = SB;
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}
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/* Unrolled loop: epilog */
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SB = S[ Order - 1 ];
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S[ Order - 1 ] = SA;
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out32_Q12 = SKP_SMLABB( out32_Q12, SA, B[ Order - 2 ] );
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out32_Q12 = SKP_SMLABB( out32_Q12, SB, B[ Order - 1 ] );
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/* Subtract prediction */
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out32_Q12 = SKP_SUB_SAT32( SKP_LSHIFT( (SKP_int32)in[ k ], 12 ), out32_Q12 );
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/* Scale to Q0 */
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out32 = SKP_RSHIFT_ROUND( out32_Q12, 12 );
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/* Saturate output */
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out[ k ] = ( SKP_int16 )SKP_SAT16( out32 );
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/* Move input line */
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S[ 0 ] = in[ k ];
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}
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}
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