diff --git a/jni/libopus/silk/quant_LTP_gains.c b/jni/libopus/silk/quant_LTP_gains.c
new file mode 100644
index 0000000..f73c0f5
--- /dev/null
+++ b/jni/libopus/silk/quant_LTP_gains.c
@@ -0,0 +1,107 @@
+/***********************************************************************
+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.h"
+
+void silk_quant_LTP_gains(
+    opus_int16                  B_Q14[ MAX_NB_SUBFR * LTP_ORDER ],          /* I/O  (un)quantized LTP gains         */
+    opus_int8                   cbk_index[ MAX_NB_SUBFR ],                  /* O    Codebook Index                  */
+    opus_int8                   *periodicity_index,                         /* O    Periodicity Index               */
+    const opus_int32            W_Q18[ MAX_NB_SUBFR*LTP_ORDER*LTP_ORDER ],  /* I    Error Weights in Q18            */
+    opus_int                    mu_Q9,                                      /* I    Mu value (R/D tradeoff)         */
+    opus_int                    lowComplexity,                              /* I    Flag for low complexity         */
+    const opus_int              nb_subfr                                    /* I    number of subframes             */
+)
+{
+    opus_int             j, k, cbk_size;
+    opus_int8            temp_idx[ MAX_NB_SUBFR ];
+    const opus_uint8     *cl_ptr_Q5;
+    const opus_int8      *cbk_ptr_Q7;
+    const opus_int16     *b_Q14_ptr;
+    const opus_int32     *W_Q18_ptr;
+    opus_int32           rate_dist_Q14_subfr, rate_dist_Q14, min_rate_dist_Q14;
+
+    /***************************************************/
+    /* iterate over different codebooks with different */
+    /* rates/distortions, and choose best */
+    /***************************************************/
+    min_rate_dist_Q14 = silk_int32_MAX;
+    for( k = 0; k < 3; k++ ) {
+        cl_ptr_Q5  = silk_LTP_gain_BITS_Q5_ptrs[ k ];
+        cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[        k ];
+        cbk_size   = silk_LTP_vq_sizes[          k ];
+
+        /* Set up pointer to first subframe */
+        W_Q18_ptr = W_Q18;
+        b_Q14_ptr = B_Q14;
+
+        rate_dist_Q14 = 0;
+        for( j = 0; j < nb_subfr; j++ ) {
+            silk_VQ_WMat_EC(
+                &temp_idx[ j ],         /* O    index of best codebook vector                           */
+                &rate_dist_Q14_subfr,   /* O    best weighted quantization error + mu * rate            */
+                b_Q14_ptr,              /* I    input vector to be quantized                            */
+                W_Q18_ptr,              /* I    weighting matrix                                        */
+                cbk_ptr_Q7,             /* I    codebook                                                */
+                cl_ptr_Q5,              /* I    code length for each codebook vector                    */
+                mu_Q9,                  /* I    tradeoff between weighted error and rate                */
+                cbk_size                /* I    number of vectors in codebook                           */
+            );
+
+            rate_dist_Q14 = silk_ADD_POS_SAT32( rate_dist_Q14, rate_dist_Q14_subfr );
+
+            b_Q14_ptr += LTP_ORDER;
+            W_Q18_ptr += LTP_ORDER * LTP_ORDER;
+        }
+
+        /* Avoid never finding a codebook */
+        rate_dist_Q14 = silk_min( silk_int32_MAX - 1, rate_dist_Q14 );
+
+        if( rate_dist_Q14 < min_rate_dist_Q14 ) {
+            min_rate_dist_Q14 = rate_dist_Q14;
+            *periodicity_index = (opus_int8)k;
+            silk_memcpy( cbk_index, temp_idx, nb_subfr * sizeof( opus_int8 ) );
+        }
+
+        /* Break early in low-complexity mode if rate distortion is below threshold */
+        if( lowComplexity && ( rate_dist_Q14 < silk_LTP_gain_middle_avg_RD_Q14 ) ) {
+            break;
+        }
+    }
+
+    cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[ *periodicity_index ];
+    for( j = 0; j < nb_subfr; j++ ) {
+        for( k = 0; k < LTP_ORDER; k++ ) {
+            B_Q14[ j * LTP_ORDER + k ] = silk_LSHIFT( cbk_ptr_Q7[ cbk_index[ j ] * LTP_ORDER + k ], 7 );
+        }
+    }
+}
+