Add copy of opus library in deps/third_party.

opus/silk/resampler_down2_3.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
+
+#include "SigProc_FIX.h"
+#include "resampler_private.h"
+
+#define ORDER_FIR                   4
+
+/* Downsample by a factor 2/3, low quality */
+void silk_resampler_down2_3(
+    opus_int32                  *S,                 /* I/O  State vector [ 6 ]                                          */
+    opus_int16                  *out,               /* O    Output signal [ floor(2*inLen/3) ]                          */
+    const opus_int16            *in,                /* I    Input signal [ inLen ]                                      */
+    opus_int32                  inLen               /* I    Number of input samples                                     */
+)
+{
+    opus_int32 nSamplesIn, counter, res_Q6;
+    opus_int32 buf[ RESAMPLER_MAX_BATCH_SIZE_IN + ORDER_FIR ];
+    opus_int32 *buf_ptr;
+
+    /* Copy buffered samples to start of buffer */
+    silk_memcpy( buf, S, ORDER_FIR * sizeof( opus_int32 ) );
+
+    /* Iterate over blocks of frameSizeIn input samples */
+    while( 1 ) {
+        nSamplesIn = silk_min( inLen, RESAMPLER_MAX_BATCH_SIZE_IN );
+
+        /* Second-order AR filter (output in Q8) */
+        silk_resampler_private_AR2( &S[ ORDER_FIR ], &buf[ ORDER_FIR ], in,
+            silk_Resampler_2_3_COEFS_LQ, nSamplesIn );
+
+        /* Interpolate filtered signal */
+        buf_ptr = buf;
+        counter = nSamplesIn;
+        while( counter > 2 ) {
+            /* Inner product */
+            res_Q6 = silk_SMULWB(         buf_ptr[ 0 ], silk_Resampler_2_3_COEFS_LQ[ 2 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 3 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 4 ] );
+
+            /* Scale down, saturate and store in output array */
+            *out++ = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( res_Q6, 6 ) );
+
+            res_Q6 = silk_SMULWB(         buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 4 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 3 ] );
+            res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 4 ], silk_Resampler_2_3_COEFS_LQ[ 2 ] );
+
+            /* Scale down, saturate and store in output array */
+            *out++ = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( res_Q6, 6 ) );
+
+            buf_ptr += 3;
+            counter -= 3;
+        }
+
+        in += nSamplesIn;
+        inLen -= nSamplesIn;
+
+        if( inLen > 0 ) {
+            /* More iterations to do; copy last part of filtered signal to beginning of buffer */
+            silk_memcpy( buf, &buf[ nSamplesIn ], ORDER_FIR * sizeof( opus_int32 ) );
+        } else {
+            break;
+        }
+    }
+
+    /* Copy last part of filtered signal to the state for the next call */
+    silk_memcpy( S, &buf[ nSamplesIn ], ORDER_FIR * sizeof( opus_int32 ) );
+}