simplified computation of LTP coefs

5 files changed, 51 insertions, 343 deletions

diff --git a/silk/float/find_LTP_FLP.c b/silk/float/find_LTP_FLP.c
index 72299960..8bc10ddf 100644
--- a/silk/float/find_LTP_FLP.c
+++ b/silk/float/find_LTP_FLP.c
@@ -33,100 +33,32 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "tuning_parameters.h"
 
 void silk_find_LTP_FLP(
-    silk_float                      b[ MAX_NB_SUBFR * LTP_ORDER ],      /* O    LTP coefs                                   */
-    silk_float                      WLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O    Weight for LTP quantization       */
-    silk_float                      *LTPredCodGain,                     /* O    LTP coding gain                             */
-    const silk_float                r_lpc[],                            /* I    LPC residual                                */
+    silk_float                      XX[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O    Weight for LTP quantization       */
+    silk_float                      xX[ MAX_NB_SUBFR * LTP_ORDER ],		/* O    Weight for LTP quantization       */
+    const silk_float                r_ptr[],                            /* I    LPC residual                                */
     const opus_int                  lag[  MAX_NB_SUBFR ],               /* I    LTP lags                                    */
-    const silk_float                Wght[ MAX_NB_SUBFR ],               /* I    Weights                                     */
     const opus_int                  subfr_length,                       /* I    Subframe length                             */
-    const opus_int                  nb_subfr,                           /* I    number of subframes                         */
-    const opus_int                  mem_offset                          /* I    Number of samples in LTP memory             */
+    const opus_int                  nb_subfr                            /* I    number of subframes                         */
 )
 {
-    opus_int   i, k;
-    silk_float *b_ptr, temp, *WLTP_ptr;
-    silk_float LPC_res_nrg, LPC_LTP_res_nrg;
-    silk_float d[ MAX_NB_SUBFR ], m, g, delta_b[ LTP_ORDER ];
-    silk_float w[ MAX_NB_SUBFR ], nrg[ MAX_NB_SUBFR ], regu;
-    silk_float Rr[ LTP_ORDER ], rr[ MAX_NB_SUBFR ];
-    const silk_float *r_ptr, *lag_ptr;
+    opus_int   k;
+    silk_float *xX_ptr, *XX_ptr;
+    const silk_float *lag_ptr;
+    silk_float xx, temp;
 
-    b_ptr    = b;
-    WLTP_ptr = WLTP;
-    r_ptr    = &r_lpc[ mem_offset ];
+    xX_ptr = xX;
+    XX_ptr = XX;
     for( k = 0; k < nb_subfr; k++ ) {
         lag_ptr = r_ptr - ( lag[ k ] + LTP_ORDER / 2 );
+        silk_corrMatrix_FLP( lag_ptr, subfr_length, LTP_ORDER, XX_ptr );
+        silk_corrVector_FLP( lag_ptr, r_ptr, subfr_length, LTP_ORDER, xX_ptr );
+        xx = ( silk_float )silk_energy_FLP( r_ptr, subfr_length );
+        temp = 1.0f / silk_max( xx, LTP_CORR_INV_MAX * 0.5f * ( XX_ptr[ 0 ] + XX_ptr[ 24 ] ) + 1.0f );
+        silk_scale_vector_FLP( XX_ptr, temp, LTP_ORDER * LTP_ORDER );
+        silk_scale_vector_FLP( xX_ptr, temp, LTP_ORDER );
 
-        silk_corrMatrix_FLP( lag_ptr, subfr_length, LTP_ORDER, WLTP_ptr );
-        silk_corrVector_FLP( lag_ptr, r_ptr, subfr_length, LTP_ORDER, Rr );
-
-        rr[ k ] = ( silk_float )silk_energy_FLP( r_ptr, subfr_length );
-        regu = 1.0f + rr[ k ] +
-            matrix_ptr( WLTP_ptr, 0, 0, LTP_ORDER ) +
-            matrix_ptr( WLTP_ptr, LTP_ORDER-1, LTP_ORDER-1, LTP_ORDER );
-        regu *= LTP_DAMPING / 3;
-        silk_regularize_correlations_FLP( WLTP_ptr, &rr[ k ], regu, LTP_ORDER );
-        silk_solve_LDL_FLP( WLTP_ptr, LTP_ORDER, Rr, b_ptr );
-
-        /* Calculate residual energy */
-        nrg[ k ] = silk_residual_energy_covar_FLP( b_ptr, WLTP_ptr, Rr, rr[ k ], LTP_ORDER );
-
-        temp = Wght[ k ] / ( nrg[ k ] * Wght[ k ] + 0.01f * subfr_length );
-        silk_scale_vector_FLP( WLTP_ptr, temp, LTP_ORDER * LTP_ORDER );
-        w[ k ] = matrix_ptr( WLTP_ptr, LTP_ORDER / 2, LTP_ORDER / 2, LTP_ORDER );
-
-        r_ptr    += subfr_length;
-        b_ptr    += LTP_ORDER;
-        WLTP_ptr += LTP_ORDER * LTP_ORDER;
-    }
-
-    /* Compute LTP coding gain */
-    if( LTPredCodGain != NULL ) {
-        LPC_LTP_res_nrg = 1e-6f;
-        LPC_res_nrg     = 0.0f;
-        for( k = 0; k < nb_subfr; k++ ) {
-            LPC_res_nrg     += rr[  k ] * Wght[ k ];
-            LPC_LTP_res_nrg += nrg[ k ] * Wght[ k ];
-        }
-
-        silk_assert( LPC_LTP_res_nrg > 0 );
-        *LTPredCodGain = 3.0f * silk_log2( LPC_res_nrg / LPC_LTP_res_nrg );
-    }
-
-    /* Smoothing */
-    /* d = sum( B, 1 ); */
-    b_ptr = b;
-    for( k = 0; k < nb_subfr; k++ ) {
-        d[ k ] = 0;
-        for( i = 0; i < LTP_ORDER; i++ ) {
-            d[ k ] += b_ptr[ i ];
-        }
-        b_ptr += LTP_ORDER;
-    }
-    /* m = ( w * d' ) / ( sum( w ) + 1e-3 ); */
-    temp = 1e-3f;
-    for( k = 0; k < nb_subfr; k++ ) {
-        temp += w[ k ];
-    }
-    m = 0;
-    for( k = 0; k < nb_subfr; k++ ) {
-        m += d[ k ] * w[ k ];
-    }
-    m = m / temp;
-
-    b_ptr = b;
-    for( k = 0; k < nb_subfr; k++ ) {
-        g = LTP_SMOOTHING / ( LTP_SMOOTHING + w[ k ] ) * ( m - d[ k ] );
-        temp = 0;
-        for( i = 0; i < LTP_ORDER; i++ ) {
-            delta_b[ i ] = silk_max_float( b_ptr[ i ], 0.1f );
-            temp += delta_b[ i ];
-        }
-        temp = g / temp;
-        for( i = 0; i < LTP_ORDER; i++ ) {
-            b_ptr[ i ] = b_ptr[ i ] + delta_b[ i ] * temp;
-        }
-        b_ptr += LTP_ORDER;
+        r_ptr  += subfr_length;
+        XX_ptr += LTP_ORDER * LTP_ORDER;
+        xX_ptr += LTP_ORDER;
     }
 }
diff --git a/silk/float/find_pred_coefs_FLP.c b/silk/float/find_pred_coefs_FLP.c
index 1af4fe5f..fc0710bc 100644
--- a/silk/float/find_pred_coefs_FLP.c
+++ b/silk/float/find_pred_coefs_FLP.c
@@ -41,7 +41,8 @@ void silk_find_pred_coefs_FLP(
 )
 {
     opus_int         i;
-    silk_float       WLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ];
+    silk_float       XXLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ];
+    silk_float       xXLTP[ MAX_NB_SUBFR * LTP_ORDER ];
     silk_float       invGains[ MAX_NB_SUBFR ], Wght[ MAX_NB_SUBFR ];
     opus_int16       NLSF_Q15[ MAX_LPC_ORDER ];
     const silk_float *x_ptr;
@@ -61,14 +62,13 @@ void silk_find_pred_coefs_FLP(
         /**********/
         silk_assert( psEnc->sCmn.ltp_mem_length - psEnc->sCmn.predictLPCOrder >= psEncCtrl->pitchL[ 0 ] + LTP_ORDER / 2 );
 
-        /* LTP analysis */
-        silk_find_LTP_FLP( psEncCtrl->LTPCoef, WLTP, &psEncCtrl->LTPredCodGain, res_pitch,
-            psEncCtrl->pitchL, Wght, psEnc->sCmn.subfr_length, psEnc->sCmn.nb_subfr, psEnc->sCmn.ltp_mem_length );
+		/* LTP analysis */
+        silk_find_LTP_FLP( XXLTP, xXLTP, &res_pitch[ psEnc->sCmn.ltp_mem_length ],
+            psEncCtrl->pitchL, psEnc->sCmn.subfr_length, psEnc->sCmn.nb_subfr );
 
         /* Quantize LTP gain parameters */
         silk_quant_LTP_gains_FLP( psEncCtrl->LTPCoef, psEnc->sCmn.indices.LTPIndex, &psEnc->sCmn.indices.PERIndex,
-            &psEnc->sCmn.sum_log_gain_Q7, WLTP, psEnc->sCmn.mu_LTP_Q9, psEnc->sCmn.LTPQuantLowComplexity, psEnc->sCmn.nb_subfr,
-            psEnc->sCmn.arch );
+			&psEncCtrl->LTPredCodGain, XXLTP, xXLTP, psEnc->sCmn.subfr_length, psEnc->sCmn.nb_subfr, psEnc->sCmn.arch );
 
         /* Control LTP scaling */
         silk_LTP_scale_ctrl_FLP( psEnc, psEncCtrl, condCoding );
@@ -91,7 +91,6 @@ void silk_find_pred_coefs_FLP(
         }
         silk_memset( psEncCtrl->LTPCoef, 0, psEnc->sCmn.nb_subfr * LTP_ORDER * sizeof( silk_float ) );
         psEncCtrl->LTPredCodGain = 0.0f;
-        psEnc->sCmn.sum_log_gain_Q7 = 0;
     }
 
     /* Limit on total predictive coding gain */
diff --git a/silk/float/main_FLP.h b/silk/float/main_FLP.h
index e5a75972..e9e32673 100644
--- a/silk/float/main_FLP.h
+++ b/silk/float/main_FLP.h
@@ -153,15 +153,12 @@ void silk_find_LPC_FLP(
 
 /* LTP analysis */
 void silk_find_LTP_FLP(
-    silk_float                      b[ MAX_NB_SUBFR * LTP_ORDER ],      /* O    LTP coefs                                   */
-    silk_float                      WLTP[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O    Weight for LTP quantization       */
-    silk_float                      *LTPredCodGain,                     /* O    LTP coding gain                             */
-    const silk_float                r_lpc[],                            /* I    LPC residual                                */
+    silk_float                      XX[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* O    Weight for LTP quantization       */
+    silk_float                      xX[ MAX_NB_SUBFR * LTP_ORDER ],		/* O    Weight for LTP quantization       */
+    const silk_float                r_ptr[],                            /* I    LPC residual                                */
     const opus_int                  lag[  MAX_NB_SUBFR ],               /* I    LTP lags                                    */
-    const silk_float                Wght[ MAX_NB_SUBFR ],               /* I    Weights                                     */
     const opus_int                  subfr_length,                       /* I    Subframe length                             */
-    const opus_int                  nb_subfr,                           /* I    number of subframes                         */
-    const opus_int                  mem_offset                          /* I    Number of samples in LTP memory             */
+    const opus_int                  nb_subfr                            /* I    number of subframes                         */
 );
 
 void silk_LTP_analysis_filter_FLP(
@@ -198,14 +195,14 @@ void silk_LPC_analysis_filter_FLP(
 
 /* LTP tap quantizer */
 void silk_quant_LTP_gains_FLP(
-    silk_float                      B[ MAX_NB_SUBFR * LTP_ORDER ],      /* I/O  (Un-)quantized LTP gains                    */
+    silk_float                      B[ MAX_NB_SUBFR * LTP_ORDER ],      /* O    Quantized LTP gains							*/
     opus_int8                       cbk_index[ MAX_NB_SUBFR ],          /* O    Codebook index                              */
     opus_int8                       *periodicity_index,                 /* O    Periodicity index                           */
-    opus_int32                      *sum_log_gain_Q7,                   /* I/O  Cumulative max prediction gain  */
-    const silk_float                W[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* I    Error weights                        */
-    const opus_int                  mu_Q10,                             /* I    Mu value (R/D tradeoff)                     */
-    const opus_int                  lowComplexity,                      /* I    Flag for low complexity                     */
-    const opus_int                  nb_subfr,                           /* I    number of subframes                         */
+	silk_float                      *pred_gain_dB,						/* O	LTP prediction gain							*/
+    const silk_float                XX[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* I    Correlation matrix					*/
+    const silk_float                xX[ MAX_NB_SUBFR * LTP_ORDER ],		/* I    Correlation vector							*/
+    const opus_int					subfr_len,							/* I    Number of samples per subframe				*/
+    const opus_int					nb_subfr,                           /* I    Number of subframes							*/
     int                             arch                                /* I    Run-time architecture                       */
 );
 
@@ -245,22 +242,6 @@ void silk_corrVector_FLP(
     silk_float                      *Xt                                 /* O    X'*t correlation vector [order]             */
 );
 
-/* Add noise to matrix diagonal */
-void silk_regularize_correlations_FLP(
-    silk_float                      *XX,                                /* I/O  Correlation matrices                        */
-    silk_float                      *xx,                                /* I/O  Correlation values                          */
-    const silk_float                noise,                              /* I    Noise energy to add                         */
-    const opus_int                  D                                   /* I    Dimension of XX                             */
-);
-
-/* Function to solve linear equation Ax = b, where A is an MxM symmetric matrix */
-void silk_solve_LDL_FLP(
-    silk_float                      *A,                                 /* I/O  Symmetric square matrix, out: reg.          */
-    const opus_int                  M,                                  /* I    Size of matrix                              */
-    const silk_float                *b,                                 /* I    Pointer to b vector                         */
-    silk_float                      *x                                  /* O    Pointer to x solution vector                */
-);
-
 /* Apply sine window to signal vector.  */
 /* Window types:                        */
 /*  1 -> sine window from 0 to pi/2     */
diff --git a/silk/float/solve_LS_FLP.c b/silk/float/solve_LS_FLP.c
deleted file mode 100644
index 7c90d665..00000000
--- a/silk/float/solve_LS_FLP.c
+++ /dev/null
@@ -1,207 +0,0 @@
-/***********************************************************************
-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 "main_FLP.h"
-#include "tuning_parameters.h"
-
-/**********************************************************************
- * LDL Factorisation. Finds the upper triangular matrix L and the diagonal
- * Matrix D (only the diagonal elements returned in a vector)such that
- * the symmetric matric A is given by A = L*D*L'.
- **********************************************************************/
-static OPUS_INLINE void silk_LDL_FLP(
-    silk_float          *A,         /* I/O  Pointer to Symetric Square Matrix                               */
-    opus_int            M,          /* I    Size of Matrix                                                  */
-    silk_float          *L,         /* I/O  Pointer to Square Upper triangular Matrix                       */
-    silk_float          *Dinv       /* I/O  Pointer to vector holding the inverse diagonal elements of D    */
-);
-
-/**********************************************************************
- * Function to solve linear equation Ax = b, when A is a MxM lower
- * triangular matrix, with ones on the diagonal.
- **********************************************************************/
-static OPUS_INLINE void silk_SolveWithLowerTriangularWdiagOnes_FLP(
-    const silk_float    *L,         /* I    Pointer to Lower Triangular Matrix                              */
-    opus_int            M,          /* I    Dim of Matrix equation                                          */
-    const silk_float    *b,         /* I    b Vector                                                        */
-    silk_float          *x          /* O    x Vector                                                        */
-);
-
-/**********************************************************************
- * Function to solve linear equation (A^T)x = b, when A is a MxM lower
- * triangular, with ones on the diagonal. (ie then A^T is upper triangular)
- **********************************************************************/
-static OPUS_INLINE void silk_SolveWithUpperTriangularFromLowerWdiagOnes_FLP(
-    const silk_float    *L,         /* I    Pointer to Lower Triangular Matrix                              */
-    opus_int            M,          /* I    Dim of Matrix equation                                          */
-    const silk_float    *b,         /* I    b Vector                                                        */
-    silk_float          *x          /* O    x Vector                                                        */
-);
-
-/**********************************************************************
- * Function to solve linear equation Ax = b, when A is a MxM
- * symmetric square matrix - using LDL factorisation
- **********************************************************************/
-void silk_solve_LDL_FLP(
-    silk_float                      *A,                                 /* I/O  Symmetric square matrix, out: reg.          */
-    const opus_int                  M,                                  /* I    Size of matrix                              */
-    const silk_float                *b,                                 /* I    Pointer to b vector                         */
-    silk_float                      *x                                  /* O    Pointer to x solution vector                */
-)
-{
-    opus_int   i;
-    silk_float L[    MAX_MATRIX_SIZE ][ MAX_MATRIX_SIZE ];
-    silk_float T[    MAX_MATRIX_SIZE ];
-    silk_float Dinv[ MAX_MATRIX_SIZE ]; /* inverse diagonal elements of D*/
-
-    silk_assert( M <= MAX_MATRIX_SIZE );
-
-    /***************************************************
-    Factorize A by LDL such that A = L*D*(L^T),
-    where L is lower triangular with ones on diagonal
-    ****************************************************/
-    silk_LDL_FLP( A, M, &L[ 0 ][ 0 ], Dinv );
-
-    /****************************************************
-    * substitute D*(L^T) = T. ie:
-    L*D*(L^T)*x = b => L*T = b <=> T = inv(L)*b
-    ******************************************************/
-    silk_SolveWithLowerTriangularWdiagOnes_FLP( &L[ 0 ][ 0 ], M, b, T );
-
-    /****************************************************
-    D*(L^T)*x = T <=> (L^T)*x = inv(D)*T, because D is
-    diagonal just multiply with 1/d_i
-    ****************************************************/
-    for( i = 0; i < M; i++ ) {
-        T[ i ] = T[ i ] * Dinv[ i ];
-    }
-    /****************************************************
-    x = inv(L') * inv(D) * T
-    *****************************************************/
-    silk_SolveWithUpperTriangularFromLowerWdiagOnes_FLP( &L[ 0 ][ 0 ], M, T, x );
-}
-
-static OPUS_INLINE void silk_SolveWithUpperTriangularFromLowerWdiagOnes_FLP(
-    const silk_float    *L,         /* I    Pointer to Lower Triangular Matrix                              */
-    opus_int            M,          /* I    Dim of Matrix equation                                          */
-    const silk_float    *b,         /* I    b Vector                                                        */
-    silk_float          *x          /* O    x Vector                                                        */
-)
-{
-    opus_int   i, j;
-    silk_float temp;
-    const silk_float *ptr1;
-
-    for( i = M - 1; i >= 0; i-- ) {
-        ptr1 =  matrix_adr( L, 0, i, M );
-        temp = 0;
-        for( j = M - 1; j > i ; j-- ) {
-            temp += ptr1[ j * M ] * x[ j ];
-        }
-        temp = b[ i ] - temp;
-        x[ i ] = temp;
-    }
-}
-
-static OPUS_INLINE void silk_SolveWithLowerTriangularWdiagOnes_FLP(
-    const silk_float    *L,         /* I    Pointer to Lower Triangular Matrix                              */
-    opus_int            M,          /* I    Dim of Matrix equation                                          */
-    const silk_float    *b,         /* I    b Vector                                                        */
-    silk_float          *x          /* O    x Vector                                                        */
-)
-{
-    opus_int   i, j;
-    silk_float temp;
-    const silk_float *ptr1;
-
-    for( i = 0; i < M; i++ ) {
-        ptr1 =  matrix_adr( L, i, 0, M );
-        temp = 0;
-        for( j = 0; j < i; j++ ) {
-            temp += ptr1[ j ] * x[ j ];
-        }
-        temp = b[ i ] - temp;
-        x[ i ] = temp;
-    }
-}
-
-static OPUS_INLINE void silk_LDL_FLP(
-    silk_float          *A,         /* I/O  Pointer to Symetric Square Matrix                               */
-    opus_int            M,          /* I    Size of Matrix                                                  */
-    silk_float          *L,         /* I/O  Pointer to Square Upper triangular Matrix                       */
-    silk_float          *Dinv       /* I/O  Pointer to vector holding the inverse diagonal elements of D    */
-)
-{
-    opus_int i, j, k, loop_count, err = 1;
-    silk_float *ptr1, *ptr2;
-    double temp, diag_min_value;
-    silk_float v[ MAX_MATRIX_SIZE ], D[ MAX_MATRIX_SIZE ]; /* temp arrays*/
-
-    silk_assert( M <= MAX_MATRIX_SIZE );
-
-    diag_min_value = FIND_LTP_COND_FAC * 0.5f * ( A[ 0 ] + A[ M * M - 1 ] );
-    for( loop_count = 0; loop_count < M && err == 1; loop_count++ ) {
-        err = 0;
-        for( j = 0; j < M; j++ ) {
-            ptr1 = matrix_adr( L, j, 0, M );
-            temp = matrix_ptr( A, j, j, M ); /* element in row j column j*/
-            for( i = 0; i < j; i++ ) {
-                v[ i ] = ptr1[ i ] * D[ i ];
-                temp  -= ptr1[ i ] * v[ i ];
-            }
-            if( temp < diag_min_value ) {
-                /* Badly conditioned matrix: add white noise and run again */
-                temp = ( loop_count + 1 ) * diag_min_value - temp;
-                for( i = 0; i < M; i++ ) {
-                    matrix_ptr( A, i, i, M ) += ( silk_float )temp;
-                }
-                err = 1;
-                break;
-            }
-            D[ j ]    = ( silk_float )temp;
-            Dinv[ j ] = ( silk_float )( 1.0f / temp );
-            matrix_ptr( L, j, j, M ) = 1.0f;
-
-            ptr1 = matrix_adr( A, j, 0, M );
-            ptr2 = matrix_adr( L, j + 1, 0, M);
-            for( i = j + 1; i < M; i++ ) {
-                temp = 0.0;
-                for( k = 0; k < j; k++ ) {
-                    temp += ptr2[ k ] * v[ k ];
-                }
-                matrix_ptr( L, i, j, M ) = ( silk_float )( ( ptr1[ i ] - temp ) * Dinv[ j ] );
-                ptr2 += M; /* go to next column*/
-            }
-        }
-    }
-    silk_assert( err == 0 );
-}
-
diff --git a/silk/float/wrappers_FLP.c b/silk/float/wrappers_FLP.c
index 6666b8ef..7e92a324 100644
--- a/silk/float/wrappers_FLP.c
+++ b/silk/float/wrappers_FLP.c
@@ -172,31 +172,34 @@ void silk_NSQ_wrapper_FLP(
 /* Floating-point Silk LTP quantiation wrapper */
 /***********************************************/
 void silk_quant_LTP_gains_FLP(
-    silk_float                      B[ MAX_NB_SUBFR * LTP_ORDER ],      /* I/O  (Un-)quantized LTP gains                    */
+    silk_float                      B[ MAX_NB_SUBFR * LTP_ORDER ],      /* O    Quantized LTP gains							*/
     opus_int8                       cbk_index[ MAX_NB_SUBFR ],          /* O    Codebook index                              */
     opus_int8                       *periodicity_index,                 /* O    Periodicity index                           */
-    opus_int32                      *sum_log_gain_Q7,                   /* I/O  Cumulative max prediction gain  */
-    const silk_float                W[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* I    Error weights                        */
-    const opus_int                  mu_Q10,                             /* I    Mu value (R/D tradeoff)                     */
-    const opus_int                  lowComplexity,                      /* I    Flag for low complexity                     */
-    const opus_int                  nb_subfr,                           /* I    number of subframes                         */
+	silk_float                      *pred_gain_dB,						/* O	LTP prediction gain							*/
+    const silk_float                XX[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ], /* I    Correlation matrix					*/
+    const silk_float                xX[ MAX_NB_SUBFR * LTP_ORDER ],		/* I    Correlation vector							*/
+    const opus_int					subfr_len,							/* I    Number of samples per subframe				*/
+    const opus_int					nb_subfr,                           /* I    Number of subframes							*/
     int                             arch                                /* I    Run-time architecture                       */
 )
 {
-    opus_int   i;
+    opus_int   i, pred_gain_dB_Q7;
     opus_int16 B_Q14[ MAX_NB_SUBFR * LTP_ORDER ];
-    opus_int32 W_Q18[ MAX_NB_SUBFR*LTP_ORDER*LTP_ORDER ];
+    opus_int32 XX_Q17[ MAX_NB_SUBFR * LTP_ORDER * LTP_ORDER ];
+    opus_int32 xX_Q17[ MAX_NB_SUBFR * LTP_ORDER ];
 
-    for( i = 0; i < nb_subfr * LTP_ORDER; i++ ) {
-        B_Q14[ i ] = (opus_int16)silk_float2int( B[ i ] * 16384.0f );
-    }
     for( i = 0; i < nb_subfr * LTP_ORDER * LTP_ORDER; i++ ) {
-        W_Q18[ i ] = (opus_int32)silk_float2int( W[ i ] * 262144.0f );
+        XX_Q17[ i ] = (opus_int32)silk_float2int( XX[ i ] * 131072.0f );
+    }
+    for( i = 0; i < nb_subfr * LTP_ORDER; i++ ) {
+        xX_Q17[ i ] = (opus_int32)silk_float2int( xX[ i ] * 131072.0f );
     }
 
-    silk_quant_LTP_gains( B_Q14, cbk_index, periodicity_index, sum_log_gain_Q7, W_Q18, mu_Q10, lowComplexity, nb_subfr, arch );
+    silk_quant_LTP_gains( B_Q14, cbk_index, periodicity_index, &pred_gain_dB_Q7, XX_Q17, xX_Q17, subfr_len, nb_subfr, arch );
 
     for( i = 0; i < nb_subfr * LTP_ORDER; i++ ) {
         B[ i ] = (silk_float)B_Q14[ i ] * ( 1.0f / 16384.0f );
     }
+
+	*pred_gain_dB = (silk_float)pred_gain_dB_Q7 * ( 1.0f / 128.0f );
 }