Add copy of opus library in deps/third_party.

opus/silk/float/schur_FLP.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_FLP.h"
+
+silk_float silk_schur_FLP(                  /* O    returns residual energy                                     */
+    silk_float          refl_coef[],        /* O    reflection coefficients (length order)                      */
+    const silk_float    auto_corr[],        /* I    autocorrelation sequence (length order+1)                   */
+    opus_int            order               /* I    order                                                       */
+)
+{
+    opus_int   k, n;
+    silk_float C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
+    silk_float Ctmp1, Ctmp2, rc_tmp;
+
+    silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 );
+
+    /* Copy correlations */
+    for( k = 0; k < order+1; k++ ) {
+        C[ k ][ 0 ] = C[ k ][ 1 ] = auto_corr[ k ];
+    }
+
+    for( k = 0; k < order; k++ ) {
+        /* Get reflection coefficient */
+        rc_tmp = -C[ k + 1 ][ 0 ] / silk_max_float( C[ 0 ][ 1 ], 1e-9f );
+
+        /* Save the output */
+        refl_coef[ k ] = rc_tmp;
+
+        /* Update correlations */
+        for( n = 0; n < order - k; n++ ) {
+            Ctmp1 = C[ n + k + 1 ][ 0 ];
+            Ctmp2 = C[ n ][ 1 ];
+            C[ n + k + 1 ][ 0 ] = Ctmp1 + Ctmp2 * rc_tmp;
+            C[ n ][ 1 ]         = Ctmp2 + Ctmp1 * rc_tmp;
+        }
+    }
+
+    /* Return residual energy */
+    return C[ 0 ][ 1 ];
+}
+