Add copy of opus library in deps/third_party.

opus/silk/fixed/schur_FIX.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"
+
+/* Faster than schur64(), but much less accurate.                       */
+/* uses SMLAWB(), requiring armv5E and higher.                          */
+opus_int32 silk_schur(                              /* O    Returns residual energy                                     */
+    opus_int16                  *rc_Q15,            /* O    reflection coefficients [order] Q15                         */
+    const opus_int32            *c,                 /* I    correlations [order+1]                                      */
+    const opus_int32            order               /* I    prediction order                                            */
+)
+{
+    opus_int        k, n, lz;
+    opus_int32    C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
+    opus_int32    Ctmp1, Ctmp2, rc_tmp_Q15;
+
+    silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 );
+
+    /* Get number of leading zeros */
+    lz = silk_CLZ32( c[ 0 ] );
+
+    /* Copy correlations and adjust level to Q30 */
+    if( lz < 2 ) {
+        /* lz must be 1, so shift one to the right */
+        for( k = 0; k < order + 1; k++ ) {
+            C[ k ][ 0 ] = C[ k ][ 1 ] = silk_RSHIFT( c[ k ], 1 );
+        }
+    } else if( lz > 2 ) {
+        /* Shift to the left */
+        lz -= 2;
+        for( k = 0; k < order + 1; k++ ) {
+            C[ k ][ 0 ] = C[ k ][ 1 ] = silk_LSHIFT( c[ k ], lz );
+        }
+    } else {
+        /* No need to shift */
+        for( k = 0; k < order + 1; k++ ) {
+            C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ];
+        }
+    }
+
+    for( k = 0; k < order; k++ ) {
+
+        /* Get reflection coefficient */
+        rc_tmp_Q15 = -silk_DIV32_16( C[ k + 1 ][ 0 ], silk_max_32( silk_RSHIFT( C[ 0 ][ 1 ], 15 ), 1 ) );
+
+        /* Clip (shouldn't happen for properly conditioned inputs) */
+        rc_tmp_Q15 = silk_SAT16( rc_tmp_Q15 );
+
+        /* Store */
+        rc_Q15[ k ] = (opus_int16)rc_tmp_Q15;
+
+        /* Update correlations */
+        for( n = 0; n < order - k; n++ ) {
+            Ctmp1 = C[ n + k + 1 ][ 0 ];
+            Ctmp2 = C[ n ][ 1 ];
+            C[ n + k + 1 ][ 0 ] = silk_SMLAWB( Ctmp1, silk_LSHIFT( Ctmp2, 1 ), rc_tmp_Q15 );
+            C[ n ][ 1 ]         = silk_SMLAWB( Ctmp2, silk_LSHIFT( Ctmp1, 1 ), rc_tmp_Q15 );
+        }
+    }
+
+    /* return residual energy */
+    return C[ 0 ][ 1 ];
+}