Add copy of opus library in deps/third_party.

opus/silk/fixed/apply_sine_window_FIX.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"
+
+/* Apply sine window to signal vector.                                      */
+/* Window types:                                                            */
+/*    1 -> sine window from 0 to pi/2                                       */
+/*    2 -> sine window from pi/2 to pi                                      */
+/* Every other sample is linearly interpolated, for speed.                  */
+/* Window length must be between 16 and 120 (incl) and a multiple of 4.     */
+
+/* Matlab code for table:
+   for k=16:9*4:16+2*9*4, fprintf(' %7.d,', -round(65536*pi ./ (k:4:k+8*4))); fprintf('\n'); end
+*/
+static const opus_int16 freq_table_Q16[ 27 ] = {
+   12111,    9804,    8235,    7100,    6239,    5565,    5022,    4575,    4202,
+    3885,    3612,    3375,    3167,    2984,    2820,    2674,    2542,    2422,
+    2313,    2214,    2123,    2038,    1961,    1889,    1822,    1760,    1702,
+};
+
+void silk_apply_sine_window(
+    opus_int16                  px_win[],           /* O    Pointer to windowed signal                                  */
+    const opus_int16            px[],               /* I    Pointer to input signal                                     */
+    const opus_int              win_type,           /* I    Selects a window type                                       */
+    const opus_int              length              /* I    Window length, multiple of 4                                */
+)
+{
+    opus_int   k, f_Q16, c_Q16;
+    opus_int32 S0_Q16, S1_Q16;
+
+    silk_assert( win_type == 1 || win_type == 2 );
+
+    /* Length must be in a range from 16 to 120 and a multiple of 4 */
+    silk_assert( length >= 16 && length <= 120 );
+    silk_assert( ( length & 3 ) == 0 );
+
+    /* Frequency */
+    k = ( length >> 2 ) - 4;
+    silk_assert( k >= 0 && k <= 26 );
+    f_Q16 = (opus_int)freq_table_Q16[ k ];
+
+    /* Factor used for cosine approximation */
+    c_Q16 = silk_SMULWB( (opus_int32)f_Q16, -f_Q16 );
+    silk_assert( c_Q16 >= -32768 );
+
+    /* initialize state */
+    if( win_type == 1 ) {
+        /* start from 0 */
+        S0_Q16 = 0;
+        /* approximation of sin(f) */
+        S1_Q16 = f_Q16 + silk_RSHIFT( length, 3 );
+    } else {
+        /* start from 1 */
+        S0_Q16 = ( (opus_int32)1 << 16 );
+        /* approximation of cos(f) */
+        S1_Q16 = ( (opus_int32)1 << 16 ) + silk_RSHIFT( c_Q16, 1 ) + silk_RSHIFT( length, 4 );
+    }
+
+    /* Uses the recursive equation:   sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f)    */
+    /* 4 samples at a time */
+    for( k = 0; k < length; k += 4 ) {
+        px_win[ k ]     = (opus_int16)silk_SMULWB( silk_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k ] );
+        px_win[ k + 1 ] = (opus_int16)silk_SMULWB( S1_Q16, px[ k + 1] );
+        S0_Q16 = silk_SMULWB( S1_Q16, c_Q16 ) + silk_LSHIFT( S1_Q16, 1 ) - S0_Q16 + 1;
+        S0_Q16 = silk_min( S0_Q16, ( (opus_int32)1 << 16 ) );
+
+        px_win[ k + 2 ] = (opus_int16)silk_SMULWB( silk_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k + 2] );
+        px_win[ k + 3 ] = (opus_int16)silk_SMULWB( S0_Q16, px[ k + 3 ] );
+        S1_Q16 = silk_SMULWB( S0_Q16, c_Q16 ) + silk_LSHIFT( S0_Q16, 1 ) - S1_Q16;
+        S1_Q16 = silk_min( S1_Q16, ( (opus_int32)1 << 16 ) );
+    }
+}