Create local copy of Opus v1.1.2

webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/find_LPC_FLP.c

Index: webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/find_LPC_FLP.c
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/find_LPC_FLP.c b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/find_LPC_FLP.c
new file mode 100644
index 0000000000000000000000000000000000000000..fcfe1c3681eb61f4273638cc42e1e17000491ede
--- /dev/null
+++ b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/find_LPC_FLP.c
@@ -0,0 +1,104 @@
+/***********************************************************************
+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 "define.h"
+#include "main_FLP.h"
+#include "tuning_parameters.h"
+
+/* LPC analysis */
+void silk_find_LPC_FLP(
+    silk_encoder_state              *psEncC,                            /* I/O  Encoder state                               */
+    opus_int16                      NLSF_Q15[],                         /* O    NLSFs                                       */
+    const silk_float                x[],                                /* I    Input signal                                */
+    const silk_float                minInvGain                          /* I    Inverse of max prediction gain              */
+)
+{
+    opus_int    k, subfr_length;
+    silk_float  a[ MAX_LPC_ORDER ];
+
+    /* Used only for NLSF interpolation */
+    silk_float  res_nrg, res_nrg_2nd, res_nrg_interp;
+    opus_int16  NLSF0_Q15[ MAX_LPC_ORDER ];
+    silk_float  a_tmp[ MAX_LPC_ORDER ];
+    silk_float  LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ];
+
+    subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
+
+    /* Default: No interpolation */
+    psEncC->indices.NLSFInterpCoef_Q2 = 4;
+
+    /* Burg AR analysis for the full frame */
+    res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder );
+
+    if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
+        /* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than        */
+        /* adding it to the residual energy of the first 10 ms in each iteration of the search below    */
+        res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder );
+
+        /* Convert to NLSFs */
+        silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder );
+
+        /* Search over interpolation indices to find the one with lowest residual energy */
+        res_nrg_2nd = silk_float_MAX;
+        for( k = 3; k >= 0; k-- ) {
+            /* Interpolate NLSFs for first half */
+            silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
+
+            /* Convert to LPC for residual energy evaluation */
+            silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder );
+
+            /* Calculate residual energy with LSF interpolation */
+            silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder );
+            res_nrg_interp = (silk_float)(
+                silk_energy_FLP( LPC_res + psEncC->predictLPCOrder,                subfr_length - psEncC->predictLPCOrder ) +
+                silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) );
+
+            /* Determine whether current interpolated NLSFs are best so far */
+            if( res_nrg_interp < res_nrg ) {
+                /* Interpolation has lower residual energy */
+                res_nrg = res_nrg_interp;
+                psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
+            } else if( res_nrg_interp > res_nrg_2nd ) {
+                /* No reason to continue iterating - residual energies will continue to climb */
+                break;
+            }
+            res_nrg_2nd = res_nrg_interp;
+        }
+    }
+
+    if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
+        /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
+        silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder );
+    }
+
+    silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 ||
+        ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
+}