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/* Cesar project {{{
 *
 * Copyright (C) 2008 Spidcom
 *
 * <<<Licence>>>
 *
 * }}} */
/**
 * \file    src/spoc.c
 * \brief   « brief description »
 * \ingroup « module »
 *
 * « long description »
 */
#include "common/std.h"
#include "hal/phy/defs.h"
#include "cp/spoc/spoc.h"
#include "math.h"

#define SPOC_PMIN PHY_CARRIER_OFFSET
#define SPOC_PMAX (PHY_CARRIER_NB + SPOC_PMIN - 1)
#define SPOC_DIAGONAL_LENGTH PHY_CARRIER_NB

spoc_prec_t kaiser[10] = { 0.9905, 0.9622, 0.9164, 0.8546, 0.7792, 0.6929, 0.5989, 0.5005, 0.4011, 0.304 };

void
spoc_CG (spoc_prec_t rho, int N, spoc_prec_t *reg)
{
    spoc_prec_t arg_p = N*M_PI*rho;
    spoc_prec_t arg_n = arg_p;
    spoc_prec_t sinus = sin (arg_p);
    if (arg_p == 0) reg[10] = 1;
    else reg[10] = sinus/arg_p;
    int k;
    spoc_prec_t kk;
    for(k=1;k<=10; k++)
    {
        sinus = -sinus;
        kk = kaiser[k-1]*sinus;
        arg_p+=M_PI;
        arg_n-=M_PI;
        /* Remarque sur la division par arg_p = pi(k-N*rho).
         * si |rho|<300ppm, N<3072, |k|<=1  alors arg_p != 0
         * et lalors arg_p=0 que si rho=0 et k=0. voir au dessus. */
        reg[k+10] = kk/arg_p;
        reg[10-k] = kk/arg_n;
    }
}

void
spoc_MCoeff (spoc_prec_t rho)
{
    int k;
    spoc_prec_t xi,xe;
    spoc_prec_t sin_xi,sin_xe;
    spoc_prec_t cos_xi,cos_xe;
    spoc_prec_t pirho = M_PI * rho;
    spoc_prec_t SIN_PIRHO = sin(pirho);
    spoc_prec_t COS_PIRHO = cos(pirho);
    spoc_prec_t delta;
    uint len;
    spoc_prec_t sin_prev;

    spoc_prec_t rho_abs = rho;
    if (rho < 0) rho_abs = -rho;
    if (rho_abs >= 1e-8)
    {
        //printf ("normal computation\n");
        xi = pirho * SPOC_PMIN;
        xe = pirho * SPOC_PMAX;
        sin_xi = sin(xi);
        sin_xe = sin(xe);
        cos_xi = cos(xi);
        len = SPOC_DIAGONAL_LENGTH - 1; // interval nb in the diagonal.

#ifdef SPOC_COMPARE_SCILAB
        args_haut[20] = xi;
        args_bas[20] = xe;
        sinc_haut[20] = sin_xi/xi;
        sinc_bas[20] = sin_xe/xe;
        divisor[20] = len*len;
        args_haut_rx[20] = -xi;
        args_bas_rx[20] = -xe;
        sinc_haut_rx[20] = sin_xi/xi;
        sinc_bas_rx[20] = sin_xe/xe;
#endif
        if (xi == 0 )
        {
            reg_ordo_tx[20] = reg_ordo_rx[20] = 1;
            reg_pente_tx[20] = reg_pente_rx[20] = 0;
        }
        else
        {
            reg_ordo_tx[20] = reg_ordo_rx[20] = sin_xi/xi;
            reg_pente_tx[20] = reg_pente_rx[20] = (sin_xe/xe - reg_ordo_tx[20])/(len*len);
        }

        delta = 0;
        /*  Diagonales superieures */
        for (k=1; k<=20; k++)
        {
            xi += (M_PI + pirho);
            xe += M_PI;
            delta += 2*M_PI;
            sin_prev = sin_xi;
            sin_xi = -sin_prev * COS_PIRHO - cos_xi * SIN_PIRHO;
            cos_xi =  sin_prev * SIN_PIRHO - cos_xi * COS_PIRHO;
            sin_xe = -sin_xe;
            sin_xi = sin(xi);
            len -= 1;
            spoc_prec_t mux = 1.0/len;
            reg_ordo_tx[k+20]  = sin_xi/xi;
            reg_ordo_rx[k+20]  = -sin_xi/(-xi+delta);
            reg_pente_tx[k+20] = (sin_xe/xe - reg_ordo_tx[k+20])*mux;
            reg_pente_rx[k+20] = (-sin_xe/(-xe+delta) - reg_ordo_rx[k+20])*mux;
#ifdef SPOC_COMPARE_SCILAB
            divisor[k+20] = len;
            args_haut[k+20] = xi;
            args_bas[k+20] = xe;
            sinc_haut[k+20] = sin_xi/xi;
            sinc_bas[k+20] = sin_xe/xe;
            args_haut_rx[k+20] = -xi+delta;
            args_bas_rx[k+20] = -xe+delta;
            sinc_haut_rx[k+20] = -sin_xi/(-xi+delta);
            sinc_bas_rx[k+20] = -sin_xe/(-xe+delta);
#endif
        }
        xi = pirho * SPOC_PMIN;
        xe = pirho * SPOC_PMAX;
        sin_xi = reg_ordo_tx[20] * xi;
        sin_xe = sin(xe);
        cos_xe = cos(xe);
        len = SPOC_DIAGONAL_LENGTH - 1;
        delta=0;
        /*  Diagonales inferieures */
        for (k=1; k<=20; k++)
        {
            xe -= (M_PI + pirho);
            xi -= M_PI;
            delta -= 2*M_PI;
            sin_prev = sin_xe;
            sin_xe = -sin_prev * COS_PIRHO + cos_xe * SIN_PIRHO;
            cos_xe = -sin_prev * SIN_PIRHO - cos_xe * COS_PIRHO;
            sin_xi = -sin_xi;
            len -= 1;
            spoc_prec_t mux = 1.0/len;
            reg_ordo_tx[20-k]  = sin_xi/xi;
            reg_ordo_rx[20-k]  = -sin_xi/(-xi+delta);
            reg_pente_tx[20-k] = (sin_xe/xe - reg_ordo_tx[20-k])*mux;
            reg_pente_rx[20-k] = (-sin_xe/(-xe+delta) - reg_ordo_rx[20-k])*mux;
#ifdef SPOC_COMPARE_SCILAB
            divisor[20-k] = len;
            args_haut[20-k] = xi;
            args_bas[20-k] = xe;
            sinc_haut[20-k] = sin_xi/xi;
            sinc_bas[20-k] = sin_xe/xe;
            args_haut_rx[20-k] = -xi+delta;
            args_bas_rx[20-k] = -xe+delta;
            sinc_haut_rx[20-k] = -sin_xi/(-xi+delta);
            sinc_bas_rx[20-k] = -sin_xe/(-xe+delta);
#endif
        }
    }
    else
    {
        //printf ("fast computation\n");
        for (k=1; k<=20; k++)
        {
            reg_ordo_tx[k+20] = reg_ordo_tx[20-k] = reg_ordo_rx[k+20] = reg_ordo_rx [20-k] = 0;
            reg_pente_tx[k+20] = reg_pente_tx[20-k]= reg_pente_rx[k+20] = reg_pente_rx [20-k]  = 0;
        }
        reg_ordo_tx[20] = reg_ordo_rx[20] = 1;
        reg_pente_tx[20] = reg_pente_rx[20] = 0;
    }
}