vdc.h

#ifndef GST_PLUGIN_VIPERDDC_VDC_H
#define GST_PLUGIN_VIPERDDC_VDC_H

/**
    The contents of this file are based on James34602's open-source version of JamesDSP
    This code is also used in JDSP4Linux.
    https://github.com/james34602/JamesDSPManager/blob/master/Open_source_edition/Audio_Engine/eclipse_libjamesdsp_free_bp/jni/vdc.h

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at
    your option) any later version.

    This program is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
    USA.
 **/

#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>

typedef struct
{
    double b0, b1, b2, a1, a2;
    double v1L, v2L, v1R, v2R; // State
} DirectForm2;

void SOS_DF2_Float_StereoProcess(DirectForm2 *df2, double x1, double x2, float *Out_y1, float *Out_y2)
{
    double w1 = x1 - df2->a1*df2->v1L - df2->a2*df2->v2L;
    double y1 = df2->b0*w1 + df2->b1*df2->v1L + df2->b2*df2->v2L;
    df2->v2L = df2->v1L;
    df2->v1L = w1;
    *Out_y1 = y1;
    double w2 = x2 - df2->a1*df2->v1R - df2->a2*df2->v2R;
    double y2 = df2->b0*w2 + df2->b1*df2->v1R + df2->b2*df2->v2R;
    df2->v2R = df2->v1R;
    df2->v1R = w2;
    *Out_y2 = y2;
}

int countChars(char* s, char c)
{
    int res = 0;
    if(s == NULL){
        return 0;
    }
    for (int i=0;i<strlen(s);i++)
        if (s[i] == c)
            res++;
    return res;
}

int get_doubleVDC(char *val, double *F)
{
    char *eptr;
    errno = 0;
    char *data = strdup(val);
    double f = strtod(data, &eptr);

    if (eptr != data && errno != ERANGE)
    {
        *F = f;
        if(data != NULL) {
            free(data);
        }
        return 1;
    }
    if(data != NULL) {
        free(data);
    }
    return 0;
}

int DDCParser(char *DDCString, DirectForm2 ***ptrdf441, DirectForm2 ***ptrdf48)
{

    char *fs44_1 = strstr(DDCString, "SR_44100");
    char *fs48 = strstr(DDCString, "SR_48000");

    int numberCount = (countChars(fs48, ',') + 1);
    int sosCount = numberCount / 5;
    DirectForm2 **df441 = (DirectForm2**)malloc(sosCount * sizeof(DirectForm2*));
    DirectForm2 **df48 = (DirectForm2**)malloc(sosCount * sizeof(DirectForm2*));
    int i;
    for (i = 0; i < sosCount; i++)
    {
        df441[i] = (DirectForm2*)malloc(sizeof(DirectForm2));
        memset(df441[i], 0, sizeof(DirectForm2));
        df48[i] = (DirectForm2*)malloc(sizeof(DirectForm2));
        memset(df48[i], 0, sizeof(DirectForm2));
    }
    double number;
    i = 0;
    int counter = 0;
    int b0b1b2a1a2 = 0;
    char *startingPoint = fs44_1 + 9;
    while (counter < numberCount)
    {
        if (get_doubleVDC(startingPoint, &number))
        {
            double val = strtod(startingPoint, &startingPoint);
            counter++;
            if (!b0b1b2a1a2)
                df441[i]->b0 = val;
            else if (b0b1b2a1a2 == 1)
                df441[i]->b1 = val;
            else if (b0b1b2a1a2 == 2)
                df441[i]->b2 = val;
            else if (b0b1b2a1a2 == 3)
                df441[i]->a1 = -val;
            else if (b0b1b2a1a2 == 4)
            {
                df441[i]->a2 = -val;
                i++;
            }
            b0b1b2a1a2++;
            if (b0b1b2a1a2 == 5)
                b0b1b2a1a2 = 0;
        }
        else
            startingPoint++;
    }
    i = 0;
    counter = 0;
    b0b1b2a1a2 = 0;
    startingPoint = fs48 + 9;
    while (counter < numberCount)
    {
        if (get_doubleVDC(startingPoint, &number))
        {
            double val = strtod(startingPoint, &startingPoint);
            counter++;
            if (!b0b1b2a1a2)
                df48[i]->b0 = val;
            else if (b0b1b2a1a2 == 1)
                df48[i]->b1 = val;
            else if (b0b1b2a1a2 == 2)
                df48[i]->b2 = val;
            else if (b0b1b2a1a2 == 3)
                df48[i]->a1 = -val;
            else if (b0b1b2a1a2 == 4)
            {
                df48[i]->a2 = -val;
                i++;
            }
            b0b1b2a1a2++;
            if (b0b1b2a1a2 == 5)
                b0b1b2a1a2 = 0;
        }
        else
            startingPoint++;
    }
    *ptrdf441 = df441;
    *ptrdf48 = df48;
    return sosCount;
}

#endif //GST_PLUGIN_VIPERDDC_VDC_H