freeswitch/libs/silk/src/SKP_Silk_MA.c

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/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, (subject to the limitations in the disclaimer below)
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are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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
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
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
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(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.
***********************************************************************/
/* *
* SKP_Silk_MA.c *
* *
* Variable order MA filter *
* *
* Copyright 2006 (c), Skype Limited *
* Date: 060221 *
* */
#include "SKP_Silk_SigProc_FIX.h"
/* Variable order MA prediction error filter */
void SKP_Silk_MA_Prediction(
const SKP_int16 *in, /* I: Input signal */
const SKP_int16 *B, /* I: MA prediction coefficients, Q12 [order] */
SKP_int32 *S, /* I/O: State vector [order] */
SKP_int16 *out, /* O: Output signal */
const SKP_int32 len, /* I: Signal length */
const SKP_int32 order /* I: Filter order */
)
{
SKP_int k, d, in16;
SKP_int32 out32;
for( k = 0; k < len; k++ ) {
in16 = in[ k ];
out32 = SKP_LSHIFT( in16, 12 ) - S[ 0 ];
out32 = SKP_RSHIFT_ROUND( out32, 12 );
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for( d = 0; d < order - 1; d++ ) {
S[ d ] = SKP_SMLABB_ovflw( S[ d + 1 ], in16, B[ d ] );
}
S[ order - 1 ] = SKP_SMULBB( in16, B[ order - 1 ] );
/* Limit */
out[ k ] = (SKP_int16)SKP_SAT16( out32 );
}
}
void SKP_Silk_LPC_analysis_filter(
const SKP_int16 *in, /* I: Input signal */
const SKP_int16 *B, /* I: MA prediction coefficients, Q12 [order] */
SKP_int16 *S, /* I/O: State vector [order] */
SKP_int16 *out, /* O: Output signal */
const SKP_int32 len, /* I: Signal length */
const SKP_int32 Order /* I: Filter order */
)
{
SKP_int k, j, idx, Order_half = SKP_RSHIFT( Order, 1 );
SKP_int32 out32_Q12, out32;
SKP_int16 SA, SB;
/* Order must be even */
SKP_assert( 2 * Order_half == Order );
/* S[] values are in Q0 */
for( k = 0; k < len; k++ ) {
SA = S[ 0 ];
out32_Q12 = 0;
for( j = 0; j < ( Order_half - 1 ); j++ ) {
idx = SKP_SMULBB( 2, j ) + 1;
/* Multiply-add two prediction coefficients for each loop */
SB = S[ idx ];
S[ idx ] = SA;
out32_Q12 = SKP_SMLABB( out32_Q12, SA, B[ idx - 1 ] );
out32_Q12 = SKP_SMLABB( out32_Q12, SB, B[ idx ] );
SA = S[ idx + 1 ];
S[ idx + 1 ] = SB;
}
/* Unrolled loop: epilog */
SB = S[ Order - 1 ];
S[ Order - 1 ] = SA;
out32_Q12 = SKP_SMLABB( out32_Q12, SA, B[ Order - 2 ] );
out32_Q12 = SKP_SMLABB( out32_Q12, SB, B[ Order - 1 ] );
/* Subtract prediction */
out32_Q12 = SKP_SUB_SAT32( SKP_LSHIFT( (SKP_int32)in[ k ], 12 ), out32_Q12 );
/* Scale to Q0 */
out32 = SKP_RSHIFT_ROUND( out32_Q12, 12 );
/* Saturate output */
out[ k ] = ( SKP_int16 )SKP_SAT16( out32 );
/* Move input line */
S[ 0 ] = in[ k ];
}
}