Add copy of opus library in deps/third_party.

opus/silk/resampler_private_AR2.c

+/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, 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 Internet Society, IETF or IETF Trust, nor the 
+names of specific contributors, may be used to endorse or promote
+products derived from this software without specific prior written
+permission.
+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 "SigProc_FIX.h"
+#include "resampler_private.h"
+
+/* Second order AR filter with single delay elements */
+void silk_resampler_private_AR2(
+    opus_int32                      S[],            /* I/O  State vector [ 2 ]          */
+    opus_int32                      out_Q8[],       /* O    Output signal               */
+    const opus_int16                in[],           /* I    Input signal                */
+    const opus_int16                A_Q14[],        /* I    AR coefficients, Q14        */
+    opus_int32                      len             /* I    Signal length               */
+)
+{
+    opus_int32    k;
+    opus_int32    out32;
+
+    for( k = 0; k < len; k++ ) {
+        out32       = silk_ADD_LSHIFT32( S[ 0 ], (opus_int32)in[ k ], 8 );
+        out_Q8[ k ] = out32;
+        out32       = silk_LSHIFT( out32, 2 );
+        S[ 0 ]      = silk_SMLAWB( S[ 1 ], out32, A_Q14[ 0 ] );
+        S[ 1 ]      = silk_SMULWB( out32, A_Q14[ 1 ] );
+    }
+}
+