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#include "SKP_Silk_main_FIX.h"

#if HIGH_PASS_INPUT

#define SKP_RADIANS_CONSTANT_Q19            1482    // 0.45f * 2.0f * 3.14159265359 / 1000
#define SKP_LOG2_VARIABLE_HP_MIN_FREQ_Q7    809     // log(80) in Q7

/* High-pass filter with cutoff frequency adaptation based on pitch lag statistics */
void SKP_Silk_HP_variable_cutoff_FIX(
    SKP_Silk_encoder_state_FIX      *psEnc,             /* I/O  Encoder state FIX                           */
    SKP_Silk_encoder_control_FIX    *psEncCtrl,         /* I/O  Encoder control FIX                         */
    SKP_int16                       *out,               /* O    high-pass filtered output signal            */
    const SKP_int16                 *in                 /* I    input signal                                */
)
{
    SKP_int   quality_Q15;
    SKP_int32 B_Q28[ 3 ], A_Q28[ 2 ];
    SKP_int32 Fc_Q19, r_Q28, r_Q22;
    SKP_int32 pitch_freq_Hz_Q16, pitch_freq_log_Q7, delta_freq_Q7;

    /*********************************************/
    /* Estimate Low End of Pitch Frequency Range */
    /*********************************************/
    if( psEnc->sCmn.prev_sigtype == SIG_TYPE_VOICED ) {
        /* difference, in log domain */
        pitch_freq_Hz_Q16 = SKP_DIV32_16( SKP_LSHIFT( SKP_MUL( psEnc->sCmn.fs_kHz, 1000 ), 16 ), psEnc->sCmn.prevLag );
        pitch_freq_log_Q7 = SKP_Silk_lin2log( pitch_freq_Hz_Q16 ) - ( 16 << 7 ); //0x70

        /* adjustment based on quality */
        quality_Q15 = psEncCtrl->input_quality_bands_Q15[ 0 ];
        pitch_freq_log_Q7 = SKP_SUB32( pitch_freq_log_Q7, SKP_SMULWB( SKP_SMULWB( SKP_LSHIFT( quality_Q15, 2 ), quality_Q15 ), 
            pitch_freq_log_Q7 - SKP_LOG2_VARIABLE_HP_MIN_FREQ_Q7 ) );
        pitch_freq_log_Q7 = SKP_ADD32( pitch_freq_log_Q7, SKP_RSHIFT( 19661 - quality_Q15, 9 ) ); // 19661_Q15 = 0.6_Q0

        //delta_freq = pitch_freq_log - psEnc->variable_HP_smth1;
        delta_freq_Q7 = pitch_freq_log_Q7 - SKP_RSHIFT( psEnc->variable_HP_smth1_Q15, 8 );
        if( delta_freq_Q7 < 0 ) {
            /* less smoothing for decreasing pitch frequency, to track something close to the minimum */
            delta_freq_Q7 = SKP_MUL( delta_freq_Q7, 3 );
        }

        /* limit delta, to reduce impact of outliers */
        delta_freq_Q7 = SKP_LIMIT_32( delta_freq_Q7, -VARIABLE_HP_MAX_DELTA_FREQ_Q7, VARIABLE_HP_MAX_DELTA_FREQ_Q7 );

        /* update smoother */
        psEnc->variable_HP_smth1_Q15 = SKP_SMLAWB( psEnc->variable_HP_smth1_Q15, 
            SKP_MUL( SKP_LSHIFT( psEnc->speech_activity_Q8, 1 ), delta_freq_Q7 ), VARIABLE_HP_SMTH_COEF1_Q16 );
    }
    /* second smoother */
    psEnc->variable_HP_smth2_Q15 = SKP_SMLAWB( psEnc->variable_HP_smth2_Q15, 
        psEnc->variable_HP_smth1_Q15 - psEnc->variable_HP_smth2_Q15, VARIABLE_HP_SMTH_COEF2_Q16 );

    /* convert from log scale to Hertz */
    psEncCtrl->pitch_freq_low_Hz = SKP_Silk_log2lin( SKP_RSHIFT( psEnc->variable_HP_smth2_Q15, 8 ) ); //pow( 2.0, psEnc->variable_HP_smth2 );

    /* limit frequency range */
    psEncCtrl->pitch_freq_low_Hz = SKP_LIMIT_32( psEncCtrl->pitch_freq_low_Hz, VARIABLE_HP_MIN_FREQ_Q0, VARIABLE_HP_MAX_FREQ_Q0 );

    /********************************/
    /* Compute Filter Coefficients  */
    /********************************/
    /* compute cut-off frequency, in radians */
    //Fc_num   = (SKP_float)( 0.45f * 2.0f * 3.14159265359 * psEncCtrl->pitch_freq_low_Hz );
    //Fc_denom = (SKP_float)( 1e3f * psEnc->sCmn.fs_kHz );
    SKP_assert( psEncCtrl->pitch_freq_low_Hz <= SKP_int32_MAX / SKP_RADIANS_CONSTANT_Q19 );
    Fc_Q19 = SKP_DIV32_16( SKP_SMULBB( SKP_RADIANS_CONSTANT_Q19, psEncCtrl->pitch_freq_low_Hz ), psEnc->sCmn.fs_kHz ); // range: 3704 - 27787, 11-15 bits
    SKP_assert( Fc_Q19 >=  3704 );
    SKP_assert( Fc_Q19 <= 27787 );

    r_Q28 = ( 1 << 28 ) - SKP_MUL( 471, Fc_Q19 ); // 471_Q9 = 0.92_Q0, range: 255347779 to 266690872, 27-28 bits
    SKP_assert( r_Q28 >= 255347779 );
    SKP_assert( r_Q28 <= 266690872 );

    /* b = r * [ 1; -2; 1 ]; */
    /* a = [ 1; -2 * r * ( 1 - 0.5 * Fc^2 ); r^2 ]; */
    B_Q28[ 0 ] = r_Q28;
    B_Q28[ 1 ] = SKP_LSHIFT( -r_Q28, 1 );
    B_Q28[ 2 ] = r_Q28;
    
    // -r * ( 2 - Fc * Fc );
    r_Q22  = SKP_RSHIFT( r_Q28, 6 );
    A_Q28[ 0 ] = SKP_SMULWW( r_Q22, SKP_SMULWW( Fc_Q19, Fc_Q19 ) - ( 2 << 22 ) );
    A_Q28[ 1 ] = SKP_SMULWW( r_Q22, r_Q22 );

    /********************************/
    /* High-Pass Filter             */
    /********************************/
    SKP_Silk_biquad_alt( in, B_Q28, A_Q28, psEnc->sCmn.In_HP_State, out, psEnc->sCmn.frame_length );
}

#endif // HIGH_PASS_INPUT
