Add copy of opus library in deps/third_party.

opus/silk/float/apply_sine_window_FLP.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_FLP.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    */
+void silk_apply_sine_window_FLP(
+    silk_float                      px_win[],                           /* O    Pointer to windowed signal                  */
+    const silk_float                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;
+    silk_float freq, c, S0, S1;
+
+    silk_assert( win_type == 1 || win_type == 2 );
+
+    /* Length must be multiple of 4 */
+    silk_assert( ( length & 3 ) == 0 );
+
+    freq = PI / ( length + 1 );
+
+    /* Approximation of 2 * cos(f) */
+    c = 2.0f - freq * freq;
+
+    /* Initialize state */
+    if( win_type < 2 ) {
+        /* Start from 0 */
+        S0 = 0.0f;
+        /* Approximation of sin(f) */
+        S1 = freq;
+    } else {
+        /* Start from 1 */
+        S0 = 1.0f;
+        /* Approximation of cos(f) */
+        S1 = 0.5f * c;
+    }
+
+    /* 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 + 0 ] = px[ k + 0 ] * 0.5f * ( S0 + S1 );
+        px_win[ k + 1 ] = px[ k + 1 ] * S1;
+        S0 = c * S1 - S0;
+        px_win[ k + 2 ] = px[ k + 2 ] * 0.5f * ( S1 + S0 );
+        px_win[ k + 3 ] = px[ k + 3 ] * S0;
+        S1 = c * S0 - S1;
+    }
+}