Add copy of opus library in deps/third_party.

opus/silk/stereo_decode_pred.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 "main.h"
+
+/* Decode mid/side predictors */
+void silk_stereo_decode_pred(
+    ec_dec                      *psRangeDec,                    /* I/O  Compressor data structure                   */
+    opus_int32                  pred_Q13[]                      /* O    Predictors                                  */
+)
+{
+    opus_int   n, ix[ 2 ][ 3 ];
+    opus_int32 low_Q13, step_Q13;
+
+    /* Entropy decoding */
+    n = ec_dec_icdf( psRangeDec, silk_stereo_pred_joint_iCDF, 8 );
+    ix[ 0 ][ 2 ] = silk_DIV32_16( n, 5 );
+    ix[ 1 ][ 2 ] = n - 5 * ix[ 0 ][ 2 ];
+    for( n = 0; n < 2; n++ ) {
+        ix[ n ][ 0 ] = ec_dec_icdf( psRangeDec, silk_uniform3_iCDF, 8 );
+        ix[ n ][ 1 ] = ec_dec_icdf( psRangeDec, silk_uniform5_iCDF, 8 );
+    }
+
+    /* Dequantize */
+    for( n = 0; n < 2; n++ ) {
+        ix[ n ][ 0 ] += 3 * ix[ n ][ 2 ];
+        low_Q13 = silk_stereo_pred_quant_Q13[ ix[ n ][ 0 ] ];
+        step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ ix[ n ][ 0 ] + 1 ] - low_Q13,
+            SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
+        pred_Q13[ n ] = silk_SMLABB( low_Q13, step_Q13, 2 * ix[ n ][ 1 ] + 1 );
+    }
+
+    /* Subtract second from first predictor (helps when actually applying these) */
+    pred_Q13[ 0 ] -= pred_Q13[ 1 ];
+}
+
+/* Decode mid-only flag */
+void silk_stereo_decode_mid_only(
+    ec_dec                      *psRangeDec,                    /* I/O  Compressor data structure                   */
+    opus_int                    *decode_only_mid                /* O    Flag that only mid channel has been coded   */
+)
+{
+    /* Decode flag that only mid channel is coded */
+    *decode_only_mid = ec_dec_icdf( psRangeDec, silk_stereo_only_code_mid_iCDF, 8 );
+}