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#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;

    celt_assert( win_type == 1 || win_type == 2 );

    /* Length must be in a range from 16 to 120 and a multiple of 4 */

    celt_assert( length >= 16 && length <= 120 );

    celt_assert( ( length & 3 ) == 0 );

    /* Frequency */

    k = ( length >> 2 ) - 4;

    celt_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 ) );

    }

}