diff options
Diffstat (limited to 'silk/float/SKP_Silk_apply_sine_window_FLP.c')
| -rw-r--r-- | silk/float/SKP_Silk_apply_sine_window_FLP.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/silk/float/SKP_Silk_apply_sine_window_FLP.c b/silk/float/SKP_Silk_apply_sine_window_FLP.c new file mode 100644 index 00000000..1db6b147 --- /dev/null +++ b/silk/float/SKP_Silk_apply_sine_window_FLP.c @@ -0,0 +1,77 @@ +/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, (subject to the limitations in the disclaimer below)
+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 Skype Limited, nor the names of specific
+contributors, may be used to endorse or promote products derived from
+this software without specific prior written permission.
+NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+BY THIS LICENSE. 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.
+***********************************************************************/
+
+#include "SKP_Silk_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 SKP_Silk_apply_sine_window_FLP(
+ SKP_float px_win[], /* O Pointer to windowed signal */
+ const SKP_float px[], /* I Pointer to input signal */
+ const SKP_int win_type, /* I Selects a window type */
+ const SKP_int length /* I Window length, multiple of 4 */
+)
+{
+ SKP_int k;
+ SKP_float freq, c, S0, S1;
+
+ SKP_assert( win_type == 1 || win_type == 2 );
+
+ /* Length must be multiple of 4 */
+ SKP_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;
+ }
+}
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