diff options
Diffstat (limited to 'silk/SKP_Silk_apply_sine_window.c')
| m--------- | silk | 6 | ||||
| -rw-r--r-- | silk/SKP_Silk_apply_sine_window.c | 97 |
2 files changed, 97 insertions, 6 deletions
diff --git a/silk b/silk deleted file mode 160000 -Subproject 8a8b76efeeccaccf402b0b2b4e469980d0a4831 diff --git a/silk/SKP_Silk_apply_sine_window.c b/silk/SKP_Silk_apply_sine_window.c new file mode 100644 index 00000000..87d71f89 --- /dev/null +++ b/silk/SKP_Silk_apply_sine_window.c @@ -0,0 +1,97 @@ +/***********************************************************************
+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_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 SKP_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 SKP_Silk_apply_sine_window(
+ SKP_int16 px_win[], /* O Pointer to windowed signal */
+ const SKP_int16 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, f_Q16, c_Q16;
+ SKP_int32 S0_Q16, S1_Q16;
+
+ SKP_assert( win_type == 1 || win_type == 2 );
+
+ /* Length must be in a range from 16 to 120 and a multiple of 4 */
+ SKP_assert( length >= 16 && length <= 120 );
+ SKP_assert( ( length & 3 ) == 0 );
+
+ /* Frequency */
+ k = ( length >> 2 ) - 4;
+ SKP_assert( k >= 0 && k <= 26 );
+ f_Q16 = (SKP_int)freq_table_Q16[ k ];
+
+ /* Factor used for cosine approximation */
+ c_Q16 = SKP_SMULWB( f_Q16, -f_Q16 );
+ SKP_assert( c_Q16 >= -32768 );
+
+ /* initialize state */
+ if( win_type == 1 ) {
+ /* start from 0 */
+ S0_Q16 = 0;
+ /* approximation of sin(f) */
+ S1_Q16 = f_Q16 + SKP_RSHIFT( length, 3 );
+ } else {
+ /* start from 1 */
+ S0_Q16 = ( 1 << 16 );
+ /* approximation of cos(f) */
+ S1_Q16 = ( 1 << 16 ) + SKP_RSHIFT( c_Q16, 1 ) + SKP_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 ] = (SKP_int16)SKP_SMULWB( SKP_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k ] );
+ px_win[ k + 1 ] = (SKP_int16)SKP_SMULWB( S1_Q16, px[ k + 1] );
+ S0_Q16 = SKP_SMULWB( S1_Q16, c_Q16 ) + SKP_LSHIFT( S1_Q16, 1 ) - S0_Q16 + 1;
+ S0_Q16 = SKP_min( S0_Q16, ( 1 << 16 ) );
+
+ px_win[ k + 2 ] = (SKP_int16)SKP_SMULWB( SKP_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k + 2] );
+ px_win[ k + 3 ] = (SKP_int16)SKP_SMULWB( S0_Q16, px[ k + 3 ] );
+ S1_Q16 = SKP_SMULWB( S0_Q16, c_Q16 ) + SKP_LSHIFT( S0_Q16, 1 ) - S1_Q16;
+ S1_Q16 = SKP_min( S1_Q16, ( 1 << 16 ) );
+ }
+}
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