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#include <stdlib.h>
#include "SKP_Silk_main_FLP.h"

/*******************************************/
/* LPC analysis filter                     */
/* NB! State is kept internally and the    */
/* filter always starts with zero state    */
/* first Order output samples are not set  */
/*******************************************/

void SKP_Silk_LPC_analysis_filter_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length,             /* I    Length of input signal                  */
    const SKP_int                   Order               /* I    LPC order                               */
)
{
    SKP_assert( Order <= length );

    switch( Order ) {
        case 6:
            SKP_Silk_LPC_analysis_filter6_FLP(  r_LPC, PredCoef, s, length );
        break;

        case 8:
            SKP_Silk_LPC_analysis_filter8_FLP(  r_LPC, PredCoef, s, length );
        break;

        case 10:
            SKP_Silk_LPC_analysis_filter10_FLP( r_LPC, PredCoef, s, length );
        break;

        case 12:
            SKP_Silk_LPC_analysis_filter12_FLP( r_LPC, PredCoef, s, length );
        break;

        case 16:
            SKP_Silk_LPC_analysis_filter16_FLP( r_LPC, PredCoef, s, length );
        break;

        default:
            SKP_assert( 0 );
        break;
    }

    /* Set first LPC Order samples to zero instead of undefined */
    SKP_memset( r_LPC, 0, Order * sizeof( SKP_float ) );
}

/* 16th order LPC analysis filter, does not write first 16 samples */
void SKP_Silk_LPC_analysis_filter16_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length              /* I    Length of input signal                  */
)
{
    SKP_int   ix = 16;
    SKP_float LPC_pred;
    const SKP_float *s_ptr;

    for ( ; ix < length; ix++) {
        s_ptr = &s[ix - 1];

        /* short-term prediction */
        LPC_pred = s_ptr[ 0 ]   * PredCoef[ 0 ]  + 
                   s_ptr[-1]  * PredCoef[ 1 ]  +
                   s_ptr[-2]  * PredCoef[ 2 ]  +
                   s_ptr[-3]  * PredCoef[ 3 ]  +
                   s_ptr[-4]  * PredCoef[ 4 ]  +
                   s_ptr[-5]  * PredCoef[ 5 ]  +
                   s_ptr[-6]  * PredCoef[ 6 ]  +
                   s_ptr[-7]  * PredCoef[ 7 ]  +
                   s_ptr[-8]  * PredCoef[ 8 ]  +
                   s_ptr[-9]  * PredCoef[ 9 ]  +
                   s_ptr[-10] * PredCoef[ 10 ] +
                   s_ptr[-11] * PredCoef[ 11 ] +
                   s_ptr[-12] * PredCoef[ 12 ] +
                   s_ptr[-13] * PredCoef[ 13 ] +
                   s_ptr[-14] * PredCoef[ 14 ] +
                   s_ptr[-15] * PredCoef[ 15 ];

        /* prediction error */
        r_LPC[ix] = s_ptr[ 1 ] - LPC_pred;
    }
}

/* 12th order LPC analysis filter, does not write first 12 samples */
void SKP_Silk_LPC_analysis_filter12_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length              /* I    Length of input signal                  */
)
{
    SKP_int   ix = 12;
    SKP_float LPC_pred;
    const SKP_float *s_ptr;

    for ( ; ix < length; ix++) {
        s_ptr = &s[ix - 1];

        /* short-term prediction */
        LPC_pred = s_ptr[ 0 ]   * PredCoef[ 0 ]  + 
                   s_ptr[-1]  * PredCoef[ 1 ]  +
                   s_ptr[-2]  * PredCoef[ 2 ]  +
                   s_ptr[-3]  * PredCoef[ 3 ]  +
                   s_ptr[-4]  * PredCoef[ 4 ]  +
                   s_ptr[-5]  * PredCoef[ 5 ]  +
                   s_ptr[-6]  * PredCoef[ 6 ]  +
                   s_ptr[-7]  * PredCoef[ 7 ]  +
                   s_ptr[-8]  * PredCoef[ 8 ]  +
                   s_ptr[-9]  * PredCoef[ 9 ]  +
                   s_ptr[-10] * PredCoef[ 10 ] +
                   s_ptr[-11] * PredCoef[ 11 ];

        /* prediction error */
        r_LPC[ix] = s_ptr[ 1 ] - LPC_pred;
    }
}

/* 10th order LPC analysis filter, does not write first 10 samples */
void SKP_Silk_LPC_analysis_filter10_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length              /* I    Length of input signal                  */
)
{
    SKP_int   ix = 10;
    SKP_float LPC_pred;
    const SKP_float *s_ptr;

    for ( ; ix < length; ix++) {
        s_ptr = &s[ix - 1];

        /* short-term prediction */
        LPC_pred = s_ptr[ 0 ]   * PredCoef[ 0 ]  + 
                   s_ptr[-1]  * PredCoef[ 1 ]  +
                   s_ptr[-2]  * PredCoef[ 2 ]  +
                   s_ptr[-3]  * PredCoef[ 3 ]  +
                   s_ptr[-4]  * PredCoef[ 4 ]  +
                   s_ptr[-5]  * PredCoef[ 5 ]  +
                   s_ptr[-6]  * PredCoef[ 6 ]  +
                   s_ptr[-7]  * PredCoef[ 7 ]  +
                   s_ptr[-8]  * PredCoef[ 8 ]  +
                   s_ptr[-9]  * PredCoef[ 9 ];

        /* prediction error */
        r_LPC[ix] = s_ptr[ 1 ] - LPC_pred;
    }
}

/* 8th order LPC analysis filter, does not write first 8 samples */
void SKP_Silk_LPC_analysis_filter8_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length              /* I    Length of input signal                  */
)
{
    SKP_int   ix = 8;
    SKP_float LPC_pred;
    const SKP_float *s_ptr;

    for ( ; ix < length; ix++) {
        s_ptr = &s[ix - 1];

        /* short-term prediction */
        LPC_pred = s_ptr[  0 ] * PredCoef[ 0 ]  + 
                   s_ptr[ -1 ] * PredCoef[ 1 ]  +
                   s_ptr[ -2 ] * PredCoef[ 2 ]  +
                   s_ptr[ -3 ] * PredCoef[ 3 ]  +
                   s_ptr[ -4 ] * PredCoef[ 4 ]  +
                   s_ptr[ -5 ] * PredCoef[ 5 ]  +
                   s_ptr[ -6 ] * PredCoef[ 6 ]  +
                   s_ptr[ -7 ] * PredCoef[ 7 ];

        /* prediction error */
        r_LPC[ix] = s_ptr[ 1 ] - LPC_pred;
    }
}

/* 6th order LPC analysis filter, does not write first 6 samples */
void SKP_Silk_LPC_analysis_filter6_FLP(
          SKP_float                 r_LPC[],            /* O    LPC residual signal                     */
    const SKP_float                 PredCoef[],         /* I    LPC coefficients                        */
    const SKP_float                 s[],                /* I    Input signal                            */
    const SKP_int                   length              /* I    Length of input signal                  */
)
{
    SKP_int   ix = 6;
    SKP_float LPC_pred;
    const SKP_float *s_ptr;

    for ( ; ix < length; ix++) {
        s_ptr = &s[ix - 1];

        /* short-term prediction */
        LPC_pred = s_ptr[  0 ] * PredCoef[ 0 ]  + 
                   s_ptr[ -1 ] * PredCoef[ 1 ]  +
                   s_ptr[ -2 ] * PredCoef[ 2 ]  +
                   s_ptr[ -3 ] * PredCoef[ 3 ]  +
                   s_ptr[ -4 ] * PredCoef[ 4 ]  +
                   s_ptr[ -5 ] * PredCoef[ 5 ];

        /* prediction error */
        r_LPC[ix] = s_ptr[ 1 ] - LPC_pred;
    }
}
