cannam@154: /***********************************************************************
cannam@154: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
cannam@154: Redistribution and use in source and binary forms, with or without
cannam@154: modification, are permitted provided that the following conditions
cannam@154: are met:
cannam@154: - Redistributions of source code must retain the above copyright notice,
cannam@154: this list of conditions and the following disclaimer.
cannam@154: - Redistributions in binary form must reproduce the above copyright
cannam@154: notice, this list of conditions and the following disclaimer in the
cannam@154: documentation and/or other materials provided with the distribution.
cannam@154: - Neither the name of Internet Society, IETF or IETF Trust, nor the
cannam@154: names of specific contributors, may be used to endorse or promote
cannam@154: products derived from this software without specific prior written
cannam@154: permission.
cannam@154: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
cannam@154: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
cannam@154: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
cannam@154: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
cannam@154: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
cannam@154: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
cannam@154: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
cannam@154: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
cannam@154: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
cannam@154: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
cannam@154: POSSIBILITY OF SUCH DAMAGE.
cannam@154: ***********************************************************************/
cannam@154: 
cannam@154: #ifdef HAVE_CONFIG_H
cannam@154: #include "config.h"
cannam@154: #endif
cannam@154: 
cannam@154: #include "SigProc_FIX.h"
cannam@154: #include "resampler_private.h"
cannam@154: 
cannam@154: /* Second order AR filter with single delay elements */
cannam@154: void silk_resampler_private_AR2(
cannam@154:     opus_int32                      S[],            /* I/O  State vector [ 2 ]          */
cannam@154:     opus_int32                      out_Q8[],       /* O    Output signal               */
cannam@154:     const opus_int16                in[],           /* I    Input signal                */
cannam@154:     const opus_int16                A_Q14[],        /* I    AR coefficients, Q14        */
cannam@154:     opus_int32                      len             /* I    Signal length               */
cannam@154: )
cannam@154: {
cannam@154:     opus_int32    k;
cannam@154:     opus_int32    out32;
cannam@154: 
cannam@154:     for( k = 0; k < len; k++ ) {
cannam@154:         out32       = silk_ADD_LSHIFT32( S[ 0 ], (opus_int32)in[ k ], 8 );
cannam@154:         out_Q8[ k ] = out32;
cannam@154:         out32       = silk_LSHIFT( out32, 2 );
cannam@154:         S[ 0 ]      = silk_SMLAWB( S[ 1 ], out32, A_Q14[ 0 ] );
cannam@154:         S[ 1 ]      = silk_SMULWB( out32, A_Q14[ 1 ] );
cannam@154:     }
cannam@154: }
cannam@154: