Create local copy of Opus v1.1.2

webrtc/modules/audio_coding/codecs/opus/opus/src/silk/LPC_inv_pred_gain.c

Index: webrtc/modules/audio_coding/codecs/opus/opus/src/silk/LPC_inv_pred_gain.c
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/LPC_inv_pred_gain.c b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/LPC_inv_pred_gain.c
new file mode 100644
index 0000000000000000000000000000000000000000..4af89aa5fad324799620e64c3fa22e3ea6bd9400
--- /dev/null
+++ b/webrtc/modules/audio_coding/codecs/opus/opus/src/silk/LPC_inv_pred_gain.c
@@ -0,0 +1,154 @@
+/***********************************************************************
+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_FIX.h"
+
+#define QA                          24
+#define A_LIMIT                     SILK_FIX_CONST( 0.99975, QA )
+
+#define MUL32_FRAC_Q(a32, b32, Q)   ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))
+
+/* Compute inverse of LPC prediction gain, and                          */
+/* test if LPC coefficients are stable (all poles within unit circle)   */
+static opus_int32 LPC_inverse_pred_gain_QA(                 /* O   Returns inverse prediction gain in energy domain, Q30    */
+    opus_int32           A_QA[ 2 ][ SILK_MAX_ORDER_LPC ],   /* I   Prediction coefficients                                  */
+    const opus_int       order                              /* I   Prediction order                                         */
+)
+{
+    opus_int   k, n, mult2Q;
+    opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp_QA;
+    opus_int32 *Aold_QA, *Anew_QA;
+
+    Anew_QA = A_QA[ order & 1 ];
+
+    invGain_Q30 = (opus_int32)1 << 30;
+    for( k = order - 1; k > 0; k-- ) {
+        /* Check for stability */
+        if( ( Anew_QA[ k ] > A_LIMIT ) || ( Anew_QA[ k ] < -A_LIMIT ) ) {
+            return 0;
+        }
+
+        /* Set RC equal to negated AR coef */
+        rc_Q31 = -silk_LSHIFT( Anew_QA[ k ], 31 - QA );
+
+        /* rc_mult1_Q30 range: [ 1 : 2^30 ] */
+        rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
+        silk_assert( rc_mult1_Q30 > ( 1 << 15 ) );                   /* reduce A_LIMIT if fails */
+        silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );
+
+        /* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */
+        mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );
+        rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );
+
+        /* Update inverse gain */
+        /* invGain_Q30 range: [ 0 : 2^30 ] */
+        invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
+        silk_assert( invGain_Q30 >= 0           );
+        silk_assert( invGain_Q30 <= ( 1 << 30 ) );
+
+        /* Swap pointers */
+        Aold_QA = Anew_QA;
+        Anew_QA = A_QA[ k & 1 ];
+
+        /* Update AR coefficient */
+        for( n = 0; n < k; n++ ) {
+            tmp_QA = Aold_QA[ n ] - MUL32_FRAC_Q( Aold_QA[ k - n - 1 ], rc_Q31, 31 );
+            Anew_QA[ n ] = MUL32_FRAC_Q( tmp_QA, rc_mult2 , mult2Q );
+        }
+    }
+
+    /* Check for stability */
+    if( ( Anew_QA[ 0 ] > A_LIMIT ) || ( Anew_QA[ 0 ] < -A_LIMIT ) ) {
+        return 0;
+    }
+
+    /* Set RC equal to negated AR coef */
+    rc_Q31 = -silk_LSHIFT( Anew_QA[ 0 ], 31 - QA );
+
+    /* Range: [ 1 : 2^30 ] */
+    rc_mult1_Q30 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
+
+    /* Update inverse gain */
+    /* Range: [ 0 : 2^30 ] */
+    invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );
+    silk_assert( invGain_Q30 >= 0     );
+    silk_assert( invGain_Q30 <= 1<<30 );
+
+    return invGain_Q30;
+}
+
+/* For input in Q12 domain */
+opus_int32 silk_LPC_inverse_pred_gain(              /* O   Returns inverse prediction gain in energy domain, Q30        */
+    const opus_int16            *A_Q12,             /* I   Prediction coefficients, Q12 [order]                         */
+    const opus_int              order               /* I   Prediction order                                             */
+)
+{
+    opus_int   k;
+    opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
+    opus_int32 *Anew_QA;
+    opus_int32 DC_resp = 0;
+
+    Anew_QA = Atmp_QA[ order & 1 ];
+
+    /* Increase Q domain of the AR coefficients */
+    for( k = 0; k < order; k++ ) {
+        DC_resp += (opus_int32)A_Q12[ k ];
+        Anew_QA[ k ] = silk_LSHIFT32( (opus_int32)A_Q12[ k ], QA - 12 );
+    }
+    /* If the DC is unstable, we don't even need to do the full calculations */
+    if( DC_resp >= 4096 ) {
+        return 0;
+    }
+    return LPC_inverse_pred_gain_QA( Atmp_QA, order );
+}
+
+#ifdef FIXED_POINT
+
+/* For input in Q24 domain */
+opus_int32 silk_LPC_inverse_pred_gain_Q24(          /* O    Returns inverse prediction gain in energy domain, Q30       */
+    const opus_int32            *A_Q24,             /* I    Prediction coefficients [order]                             */
+    const opus_int              order               /* I    Prediction order                                            */
+)
+{
+    opus_int   k;
+    opus_int32 Atmp_QA[ 2 ][ SILK_MAX_ORDER_LPC ];
+    opus_int32 *Anew_QA;
+
+    Anew_QA = Atmp_QA[ order & 1 ];
+
+    /* Increase Q domain of the AR coefficients */
+    for( k = 0; k < order; k++ ) {
+        Anew_QA[ k ] = silk_RSHIFT32( A_Q24[ k ], 24 - QA );
+    }
+
+    return LPC_inverse_pred_gain_QA( Atmp_QA, order );
+}
+#endif