ref: aa5ea6ee520f846610dd3a70942473df021bd361
dir: /silk/silk_resampler_private_ARMA4.c/
/*********************************************************************** 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) 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. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name of Skype Limited, nor the names of specific contributors, may be used to endorse or promote products derived from this software without specific prior written permission. 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 CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, 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, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 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 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ***********************************************************************/ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "silk_SigProc_FIX.h" #include "silk_resampler_private.h" /* Fourth order ARMA filter */ /* Internally operates as two biquad filters in sequence. */ /* Coeffients are stored in a packed format: */ /* { B1_Q14[1], B2_Q14[1], -A1_Q14[1], -A1_Q14[2], -A2_Q14[1], -A2_Q14[2], gain_Q16 } */ /* where it is assumed that B*_Q14[0], B*_Q14[2], A*_Q14[0] are all 16384 */ void silk_resampler_private_ARMA4( opus_int32 S[], /* I/O: State vector [ 4 ] */ opus_int16 out[], /* O: Output signal */ const opus_int16 in[], /* I: Input signal */ const opus_int16 Coef[], /* I: ARMA coefficients [ 7 ] */ opus_int32 len /* I: Signal length */ ) { opus_int32 k; opus_int32 in_Q8, out1_Q8, out2_Q8, X; for( k = 0; k < len; k++ ) { in_Q8 = SKP_LSHIFT32( (opus_int32)in[ k ], 8 ); /* Outputs of first and second biquad */ out1_Q8 = SKP_ADD_LSHIFT32( in_Q8, S[ 0 ], 2 ); out2_Q8 = SKP_ADD_LSHIFT32( out1_Q8, S[ 2 ], 2 ); /* Update states, which are stored in Q6. Coefficients are in Q14 here */ X = SKP_SMLAWB( S[ 1 ], in_Q8, Coef[ 0 ] ); S[ 0 ] = SKP_SMLAWB( X, out1_Q8, Coef[ 2 ] ); X = SKP_SMLAWB( S[ 3 ], out1_Q8, Coef[ 1 ] ); S[ 2 ] = SKP_SMLAWB( X, out2_Q8, Coef[ 4 ] ); S[ 1 ] = SKP_SMLAWB( SKP_RSHIFT32( in_Q8, 2 ), out1_Q8, Coef[ 3 ] ); S[ 3 ] = SKP_SMLAWB( SKP_RSHIFT32( out1_Q8, 2 ), out2_Q8, Coef[ 5 ] ); /* Apply gain and store to output. The coefficient is in Q16 */ out[ k ] = (opus_int16)SKP_SAT16( SKP_RSHIFT32( SKP_SMLAWB( 128, out2_Q8, Coef[ 6 ] ), 8 ) ); } }