Create local copy of Opus v1.1.2

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

Index: webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/burg_modified_FLP.c
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/burg_modified_FLP.c b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/burg_modified_FLP.c
new file mode 100644
index 0000000000000000000000000000000000000000..ea5dc25a93a7e2bcded3129beb73faeb1278b01a
--- /dev/null
+++ b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/float/burg_modified_FLP.c
@@ -0,0 +1,186 @@
+/***********************************************************************
+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"
+#include "tuning_parameters.h"
+#include "define.h"
+
+#define MAX_FRAME_SIZE              384 /* subfr_length * nb_subfr = ( 0.005 * 16000 + 16 ) * 4 = 384*/
+
+/* Compute reflection coefficients from input signal */
+silk_float silk_burg_modified_FLP(          /* O    returns residual energy                                     */
+    silk_float          A[],                /* O    prediction coefficients (length order)                      */
+    const silk_float    x[],                /* I    input signal, length: nb_subfr*(D+L_sub)                    */
+    const silk_float    minInvGain,         /* I    minimum inverse prediction gain                             */
+    const opus_int      subfr_length,       /* I    input signal subframe length (incl. D preceding samples)    */
+    const opus_int      nb_subfr,           /* I    number of subframes stacked in x                            */
+    const opus_int      D                   /* I    order                                                       */
+)
+{
+    opus_int         k, n, s, reached_max_gain;
+    double           C0, invGain, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2;
+    const silk_float *x_ptr;
+    double           C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ];
+    double           CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ];
+    double           Af[ SILK_MAX_ORDER_LPC ];
+
+    silk_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE );
+
+    /* Compute autocorrelations, added over subframes */
+    C0 = silk_energy_FLP( x, nb_subfr * subfr_length );
+    silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) );
+    for( s = 0; s < nb_subfr; s++ ) {
+        x_ptr = x + s * subfr_length;
+        for( n = 1; n < D + 1; n++ ) {
+            C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n );
+        }
+    }
+    silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) );
+
+    /* Initialize */
+    CAb[ 0 ] = CAf[ 0 ] = C0 + FIND_LPC_COND_FAC * C0 + 1e-9f;
+    invGain = 1.0f;
+    reached_max_gain = 0;
+    for( n = 0; n < D; n++ ) {
+        /* Update first row of correlation matrix (without first element) */
+        /* Update last row of correlation matrix (without last element, stored in reversed order) */
+        /* Update C * Af */
+        /* Update C * flipud(Af) (stored in reversed order) */
+        for( s = 0; s < nb_subfr; s++ ) {
+            x_ptr = x + s * subfr_length;
+            tmp1 = x_ptr[ n ];
+            tmp2 = x_ptr[ subfr_length - n - 1 ];
+            for( k = 0; k < n; k++ ) {
+                C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ];
+                C_last_row[ k ]  -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ];
+                Atmp = Af[ k ];
+                tmp1 += x_ptr[ n - k - 1 ] * Atmp;
+                tmp2 += x_ptr[ subfr_length - n + k ] * Atmp;
+            }
+            for( k = 0; k <= n; k++ ) {
+                CAf[ k ] -= tmp1 * x_ptr[ n - k ];
+                CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ];
+            }
+        }
+        tmp1 = C_first_row[ n ];
+        tmp2 = C_last_row[ n ];
+        for( k = 0; k < n; k++ ) {
+            Atmp = Af[ k ];
+            tmp1 += C_last_row[  n - k - 1 ] * Atmp;
+            tmp2 += C_first_row[ n - k - 1 ] * Atmp;
+        }
+        CAf[ n + 1 ] = tmp1;
+        CAb[ n + 1 ] = tmp2;
+
+        /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */
+        num = CAb[ n + 1 ];
+        nrg_b = CAb[ 0 ];
+        nrg_f = CAf[ 0 ];
+        for( k = 0; k < n; k++ ) {
+            Atmp = Af[ k ];
+            num   += CAb[ n - k ] * Atmp;
+            nrg_b += CAb[ k + 1 ] * Atmp;
+            nrg_f += CAf[ k + 1 ] * Atmp;
+        }
+        silk_assert( nrg_f > 0.0 );
+        silk_assert( nrg_b > 0.0 );
+
+        /* Calculate the next order reflection (parcor) coefficient */
+        rc = -2.0 * num / ( nrg_f + nrg_b );
+        silk_assert( rc > -1.0 && rc < 1.0 );
+
+        /* Update inverse prediction gain */
+        tmp1 = invGain * ( 1.0 - rc * rc );
+        if( tmp1 <= minInvGain ) {
+            /* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */
+            rc = sqrt( 1.0 - minInvGain / invGain );
+            if( num > 0 ) {
+                /* Ensure adjusted reflection coefficients has the original sign */
+                rc = -rc;
+            }
+            invGain = minInvGain;
+            reached_max_gain = 1;
+        } else {
+            invGain = tmp1;
+        }
+
+        /* Update the AR coefficients */
+        for( k = 0; k < (n + 1) >> 1; k++ ) {
+            tmp1 = Af[ k ];
+            tmp2 = Af[ n - k - 1 ];
+            Af[ k ]         = tmp1 + rc * tmp2;
+            Af[ n - k - 1 ] = tmp2 + rc * tmp1;
+        }
+        Af[ n ] = rc;
+
+        if( reached_max_gain ) {
+            /* Reached max prediction gain; set remaining coefficients to zero and exit loop */
+            for( k = n + 1; k < D; k++ ) {
+                Af[ k ] = 0.0;
+            }
+            break;
+        }
+
+        /* Update C * Af and C * Ab */
+        for( k = 0; k <= n + 1; k++ ) {
+            tmp1 = CAf[ k ];
+            CAf[ k ]          += rc * CAb[ n - k + 1 ];
+            CAb[ n - k + 1  ] += rc * tmp1;
+        }
+    }
+
+    if( reached_max_gain ) {
+        /* Convert to silk_float */
+        for( k = 0; k < D; k++ ) {
+            A[ k ] = (silk_float)( -Af[ k ] );
+        }
+        /* Subtract energy of preceding samples from C0 */
+        for( s = 0; s < nb_subfr; s++ ) {
+            C0 -= silk_energy_FLP( x + s * subfr_length, D );
+        }
+        /* Approximate residual energy */
+        nrg_f = C0 * invGain;
+    } else {
+        /* Compute residual energy and store coefficients as silk_float */
+        nrg_f = CAf[ 0 ];
+        tmp1 = 1.0;
+        for( k = 0; k < D; k++ ) {
+            Atmp = Af[ k ];
+            nrg_f += CAf[ k + 1 ] * Atmp;
+            tmp1  += Atmp * Atmp;
+            A[ k ] = (silk_float)(-Atmp);
+        }
+        nrg_f -= FIND_LPC_COND_FAC * C0 * tmp1;
+    }
+
+    /* Return residual energy */
+    return (silk_float)nrg_f;
+}