#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
/*
 * Stolen from gnumeric
 *
 * Original code from Morten Welinder <terra@gnome.org>
 */

#include <stdio.h>
#include <limits.h>

#include "continued-fraction.h"

void sa_continued_fraction(double val, int max_denom, int *res_num, int *res_denom) {
    int n1, n2, d1, d2;
    double x, y;

    if (val < 0) {
        sa_continued_fraction (-val, max_denom, res_num, res_denom);
        *res_num = -*res_num;
        return;
    }

    n1 = 0; d1 = 1;
    n2 = 1; d2 = 0;

    x = val;
    y = 1;

    do {
        int a = (int) (x / y);
        double newy = x - a * y;
        int n3, d3;

        if ((n2 && a > (INT_MAX - n1) / n2) ||
            (d2 && a > (INT_MAX - d1) / d2) ||
            a * d2 + d1 > max_denom) {
            *res_num = n2;
            *res_denom = d2;
            return;
        }

        n3 = a * n2 + n1;
        d3 = a * d2 + d1;

        x = y;
        y = newy;

        n1 = n2; n2 = n3;
        d1 = d2; d2 = d3;
    } while (y > 1e-10);

    *res_num = n2;
    *res_denom = d2;
}

#if 0

int main(int argc, char*argv[]) {

    float value = 3.1417235;
    int res_num, res_denom;

    sa_continued_fraction(value, 0xFFFF, &res_num, &res_denom);

    printf("%g ~= %i/%i = %g\n", value, res_num, res_denom, (float) res_num / res_denom);

    return 0;
}

#endif