Add copy of opus library in deps/third_party.

opus/silk/LP_variable_cutoff.c

+/***********************************************************************
+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
+
+/*
+    Elliptic/Cauer filters designed with 0.1 dB passband ripple,
+    80 dB minimum stopband attenuation, and
+    [0.95 : 0.15 : 0.35] normalized cut off frequencies.
+*/
+
+#include "main.h"
+
+/* Helper function, interpolates the filter taps */
+static inline void silk_LP_interpolate_filter_taps(
+    opus_int32           B_Q28[ TRANSITION_NB ],
+    opus_int32           A_Q28[ TRANSITION_NA ],
+    const opus_int       ind,
+    const opus_int32     fac_Q16
+)
+{
+    opus_int nb, na;
+
+    if( ind < TRANSITION_INT_NUM - 1 ) {
+        if( fac_Q16 > 0 ) {
+            if( fac_Q16 < 32768 ) { /* fac_Q16 is in range of a 16-bit int */
+                /* Piece-wise linear interpolation of B and A */
+                for( nb = 0; nb < TRANSITION_NB; nb++ ) {
+                    B_Q28[ nb ] = silk_SMLAWB(
+                        silk_Transition_LP_B_Q28[ ind     ][ nb ],
+                        silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
+                        silk_Transition_LP_B_Q28[ ind     ][ nb ],
+                        fac_Q16 );
+                }
+                for( na = 0; na < TRANSITION_NA; na++ ) {
+                    A_Q28[ na ] = silk_SMLAWB(
+                        silk_Transition_LP_A_Q28[ ind     ][ na ],
+                        silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
+                        silk_Transition_LP_A_Q28[ ind     ][ na ],
+                        fac_Q16 );
+                }
+            } else { /* ( fac_Q16 - ( 1 << 16 ) ) is in range of a 16-bit int */
+                silk_assert( fac_Q16 - ( 1 << 16 ) == silk_SAT16( fac_Q16 - ( 1 << 16 ) ) );
+                /* Piece-wise linear interpolation of B and A */
+                for( nb = 0; nb < TRANSITION_NB; nb++ ) {
+                    B_Q28[ nb ] = silk_SMLAWB(
+                        silk_Transition_LP_B_Q28[ ind + 1 ][ nb ],
+                        silk_Transition_LP_B_Q28[ ind + 1 ][ nb ] -
+                        silk_Transition_LP_B_Q28[ ind     ][ nb ],
+                        fac_Q16 - ( (opus_int32)1 << 16 ) );
+                }
+                for( na = 0; na < TRANSITION_NA; na++ ) {
+                    A_Q28[ na ] = silk_SMLAWB(
+                        silk_Transition_LP_A_Q28[ ind + 1 ][ na ],
+                        silk_Transition_LP_A_Q28[ ind + 1 ][ na ] -
+                        silk_Transition_LP_A_Q28[ ind     ][ na ],
+                        fac_Q16 - ( (opus_int32)1 << 16 ) );
+                }
+            }
+        } else {
+            silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ ind ], TRANSITION_NB * sizeof( opus_int32 ) );
+            silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ ind ], TRANSITION_NA * sizeof( opus_int32 ) );
+        }
+    } else {
+        silk_memcpy( B_Q28, silk_Transition_LP_B_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NB * sizeof( opus_int32 ) );
+        silk_memcpy( A_Q28, silk_Transition_LP_A_Q28[ TRANSITION_INT_NUM - 1 ], TRANSITION_NA * sizeof( opus_int32 ) );
+    }
+}
+
+/* Low-pass filter with variable cutoff frequency based on  */
+/* piece-wise linear interpolation between elliptic filters */
+/* Start by setting psEncC->mode <> 0;                      */
+/* Deactivate by setting psEncC->mode = 0;                  */
+void silk_LP_variable_cutoff(
+    silk_LP_state               *psLP,                          /* I/O  LP filter state                             */
+    opus_int16                  *frame,                         /* I/O  Low-pass filtered output signal             */
+    const opus_int              frame_length                    /* I    Frame length                                */
+)
+{
+    opus_int32   B_Q28[ TRANSITION_NB ], A_Q28[ TRANSITION_NA ], fac_Q16 = 0;
+    opus_int     ind = 0;
+
+    silk_assert( psLP->transition_frame_no >= 0 && psLP->transition_frame_no <= TRANSITION_FRAMES );
+
+    /* Run filter if needed */
+    if( psLP->mode != 0 ) {
+        /* Calculate index and interpolation factor for interpolation */
+#if( TRANSITION_INT_STEPS == 64 )
+        fac_Q16 = silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 - 6 );
+#else
+        fac_Q16 = silk_DIV32_16( silk_LSHIFT( TRANSITION_FRAMES - psLP->transition_frame_no, 16 ), TRANSITION_FRAMES );
+#endif
+        ind      = silk_RSHIFT( fac_Q16, 16 );
+        fac_Q16 -= silk_LSHIFT( ind, 16 );
+
+        silk_assert( ind >= 0 );
+        silk_assert( ind < TRANSITION_INT_NUM );
+
+        /* Interpolate filter coefficients */
+        silk_LP_interpolate_filter_taps( B_Q28, A_Q28, ind, fac_Q16 );
+
+        /* Update transition frame number for next frame */
+        psLP->transition_frame_no = silk_LIMIT( psLP->transition_frame_no + psLP->mode, 0, TRANSITION_FRAMES );
+
+        /* ARMA low-pass filtering */
+        silk_assert( TRANSITION_NB == 3 && TRANSITION_NA == 2 );
+        silk_biquad_alt( frame, B_Q28, A_Q28, psLP->In_LP_State, frame, frame_length, 1);
+    }
+}