78 lines
3.7 KiB
C
Executable File
78 lines
3.7 KiB
C
Executable File
/***********************************************************************
|
|
Copyright (c) 2006-2012, 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;
|
|
}
|
|
}
|