Add copy of opus library in deps/third_party.

opus/silk/NLSF_stabilize.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
+
+/* NLSF stabilizer:                                         */
+/*                                                          */
+/* - Moves NLSFs futher apart if they are too close         */
+/* - Moves NLSFs away from borders if they are too close    */
+/* - High effort to achieve a modification with minimum     */
+/*     Euclidean distance to input vector                   */
+/* - Output are sorted NLSF coefficients                    */
+/*                                                          */
+
+#include "SigProc_FIX.h"
+
+/* Constant Definitions */
+#define MAX_LOOPS        20
+
+/* NLSF stabilizer, for a single input data vector */
+void silk_NLSF_stabilize(
+          opus_int16            *NLSF_Q15,          /* I/O   Unstable/stabilized normalized LSF vector in Q15 [L]       */
+    const opus_int16            *NDeltaMin_Q15,     /* I     Min distance vector, NDeltaMin_Q15[L] must be >= 1 [L+1]   */
+    const opus_int              L                   /* I     Number of NLSF parameters in the input vector              */
+)
+{
+    opus_int   i, I=0, k, loops;
+    opus_int16 center_freq_Q15;
+    opus_int32 diff_Q15, min_diff_Q15, min_center_Q15, max_center_Q15;
+
+    /* This is necessary to ensure an output within range of a opus_int16 */
+    silk_assert( NDeltaMin_Q15[L] >= 1 );
+
+    for( loops = 0; loops < MAX_LOOPS; loops++ ) {
+        /**************************/
+        /* Find smallest distance */
+        /**************************/
+        /* First element */
+        min_diff_Q15 = NLSF_Q15[0] - NDeltaMin_Q15[0];
+        I = 0;
+        /* Middle elements */
+        for( i = 1; i <= L-1; i++ ) {
+            diff_Q15 = NLSF_Q15[i] - ( NLSF_Q15[i-1] + NDeltaMin_Q15[i] );
+            if( diff_Q15 < min_diff_Q15 ) {
+                min_diff_Q15 = diff_Q15;
+                I = i;
+            }
+        }
+        /* Last element */
+        diff_Q15 = ( 1 << 15 ) - ( NLSF_Q15[L-1] + NDeltaMin_Q15[L] );
+        if( diff_Q15 < min_diff_Q15 ) {
+            min_diff_Q15 = diff_Q15;
+            I = L;
+        }
+
+        /***************************************************/
+        /* Now check if the smallest distance non-negative */
+        /***************************************************/
+        if( min_diff_Q15 >= 0 ) {
+            return;
+        }
+
+        if( I == 0 ) {
+            /* Move away from lower limit */
+            NLSF_Q15[0] = NDeltaMin_Q15[0];
+
+        } else if( I == L) {
+            /* Move away from higher limit */
+            NLSF_Q15[L-1] = ( 1 << 15 ) - NDeltaMin_Q15[L];
+
+        } else {
+            /* Find the lower extreme for the location of the current center frequency */
+            min_center_Q15 = 0;
+            for( k = 0; k < I; k++ ) {
+                min_center_Q15 += NDeltaMin_Q15[k];
+            }
+            min_center_Q15 += silk_RSHIFT( NDeltaMin_Q15[I], 1 );
+
+            /* Find the upper extreme for the location of the current center frequency */
+            max_center_Q15 = 1 << 15;
+            for( k = L; k > I; k-- ) {
+                max_center_Q15 -= NDeltaMin_Q15[k];
+            }
+            max_center_Q15 -= silk_RSHIFT( NDeltaMin_Q15[I], 1 );
+
+            /* Move apart, sorted by value, keeping the same center frequency */
+            center_freq_Q15 = (opus_int16)silk_LIMIT_32( silk_RSHIFT_ROUND( (opus_int32)NLSF_Q15[I-1] + (opus_int32)NLSF_Q15[I], 1 ),
+                min_center_Q15, max_center_Q15 );
+            NLSF_Q15[I-1] = center_freq_Q15 - silk_RSHIFT( NDeltaMin_Q15[I], 1 );
+            NLSF_Q15[I] = NLSF_Q15[I-1] + NDeltaMin_Q15[I];
+        }
+    }
+
+    /* Safe and simple fall back method, which is less ideal than the above */
+    if( loops == MAX_LOOPS )
+    {
+        /* Insertion sort (fast for already almost sorted arrays):   */
+        /* Best case:  O(n)   for an already sorted array            */
+        /* Worst case: O(n^2) for an inversely sorted array          */
+        silk_insertion_sort_increasing_all_values_int16( &NLSF_Q15[0], L );
+
+        /* First NLSF should be no less than NDeltaMin[0] */
+        NLSF_Q15[0] = silk_max_int( NLSF_Q15[0], NDeltaMin_Q15[0] );
+
+        /* Keep delta_min distance between the NLSFs */
+        for( i = 1; i < L; i++ )
+            NLSF_Q15[i] = silk_max_int( NLSF_Q15[i], NLSF_Q15[i-1] + NDeltaMin_Q15[i] );
+
+        /* Last NLSF should be no higher than 1 - NDeltaMin[L] */
+        NLSF_Q15[L-1] = silk_min_int( NLSF_Q15[L-1], (1<<15) - NDeltaMin_Q15[L] );
+
+        /* Keep NDeltaMin distance between the NLSFs */
+        for( i = L-2; i >= 0; i-- )
+            NLSF_Q15[i] = silk_min_int( NLSF_Q15[i], NLSF_Q15[i+1] - NDeltaMin_Q15[i+1] );
+    }
+}