michael@0: /***********************************************************************
michael@0: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
michael@0: Redistribution and use in source and binary forms, with or without
michael@0: modification, are permitted provided that the following conditions
michael@0: are met:
michael@0: - Redistributions of source code must retain the above copyright notice,
michael@0: this list of conditions and the following disclaimer.
michael@0: - Redistributions in binary form must reproduce the above copyright
michael@0: notice, this list of conditions and the following disclaimer in the
michael@0: documentation and/or other materials provided with the distribution.
michael@0: - Neither the name of Internet Society, IETF or IETF Trust, nor the
michael@0: names of specific contributors, may be used to endorse or promote
michael@0: products derived from this software without specific prior written
michael@0: permission.
michael@0: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
michael@0: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
michael@0: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
michael@0: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
michael@0: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
michael@0: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
michael@0: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
michael@0: POSSIBILITY OF SUCH DAMAGE.
michael@0: ***********************************************************************/
michael@0: 
michael@0: #ifdef HAVE_CONFIG_H
michael@0: #include "config.h"
michael@0: #endif
michael@0: 
michael@0: #include "SigProc_FIX.h"
michael@0: #include "resampler_private.h"
michael@0: 
michael@0: /* Second order AR filter with single delay elements */
michael@0: void silk_resampler_private_AR2(
michael@0:     opus_int32                      S[],            /* I/O  State vector [ 2 ]          */
michael@0:     opus_int32                      out_Q8[],       /* O    Output signal               */
michael@0:     const opus_int16                in[],           /* I    Input signal                */
michael@0:     const opus_int16                A_Q14[],        /* I    AR coefficients, Q14        */
michael@0:     opus_int32                      len             /* I    Signal length               */
michael@0: )
michael@0: {
michael@0:     opus_int32    k;
michael@0:     opus_int32    out32;
michael@0: 
michael@0:     for( k = 0; k < len; k++ ) {
michael@0:         out32       = silk_ADD_LSHIFT32( S[ 0 ], (opus_int32)in[ k ], 8 );
michael@0:         out_Q8[ k ] = out32;
michael@0:         out32       = silk_LSHIFT( out32, 2 );
michael@0:         S[ 0 ]      = silk_SMLAWB( S[ 1 ], out32, A_Q14[ 0 ] );
michael@0:         S[ 1 ]      = silk_SMULWB( out32, A_Q14[ 1 ] );
michael@0:     }
michael@0: }
michael@0: