#include <math.h>
#include <stdlib.h>
#include <stdio.h>

#define ipow(n, e) (int)pow(n, e)
#define buf_update(n) printf("buf: %d\n", n)


void _connegbase(int n, int r, int e)
{
    /*
     * Gives 1  1  8  70  1 for digit values which is obviously wrong
     * for -124 converting to base -10
     */

    /* Takes the number to be converted n, and the base to convert to r */
    int     m;


    /* Find minimum multiplicator of |r^e| that is > |n| */
    for (m = 0; m * abs(ipow(r, e)) < abs(n); ++m) {
    ;
    }

    buf_update(m);

    if (e && n) {
    /* | m * r^e - |n| | passed as n */
    _connegbase(n - (m * ipow(r, e)), r, e-1);
    }

    return;
}


void
connegbase(int n, int r)
{
    int _exp = -1;
    int _pow;
    int _powpos = 0;
    int _npos = 0;


    if ( r < 0 ) {

        do {

            _pow = ipow(r, ++_exp);
            _powpos = (_pow>=0)?1:0;
            _npos = (n>=0)?1:0;

            if ( abs(_pow) > abs(n) ) {

                if ((!_powpos && !_npos)  || (_powpos && _npos)){
                    break;
                } else if ((_powpos && !_npos) || (!_powpos && _npos) ) {
                    _exp--;
                    break;
                }

            }

        } while (1);

        _connegbase(n, r, _exp);

    } // r < 0
}

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

    printf("<\n");
    connegbase(1240, -10);

    printf("<\n");
    connegbase(124, -10);

    printf("<\n");
    connegbase(-1240, -10);

    printf("<\n");
    connegbase(-124, -10);

    printf("<\n");
    connegbase(0,-10);

    return 0;
}