Add copy of opus library in deps/third_party.

opus/silk/fixed/k2a_FIX.c

+/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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+modification, are permitted provided that the following conditions
+are met:
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+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"
+
+/* Step up function, converts reflection coefficients to prediction coefficients */
+void silk_k2a(
+    opus_int32                  *A_Q24,             /* O    Prediction coefficients [order] Q24                         */
+    const opus_int16            *rc_Q15,            /* I    Reflection coefficients [order] Q15                         */
+    const opus_int32            order               /* I    Prediction order                                            */
+)
+{
+    opus_int   k, n;
+    opus_int32 Atmp[ SILK_MAX_ORDER_LPC ];
+
+    for( k = 0; k < order; k++ ) {
+        for( n = 0; n < k; n++ ) {
+            Atmp[ n ] = A_Q24[ n ];
+        }
+        for( n = 0; n < k; n++ ) {
+            A_Q24[ n ] = silk_SMLAWB( A_Q24[ n ], silk_LSHIFT( Atmp[ k - n - 1 ], 1 ), rc_Q15[ k ] );
+        }
+        A_Q24[ k ] = -silk_LSHIFT( (opus_int32)rc_Q15[ k ], 9 );
+    }
+}