x mod((2^n)-1) by single digit sum

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

#define MAX_DIG   128 //maximum digits in any base
#define MAX_BASES 16 //maximum number of bases stored


typedef unsigned long long uint;
typedef long long sint;

typedef struct {
  uint N; //number of digits
  uint d[MAX_DIG]; //digits of a number
  uint r; //remainder, d mod(base-1)
} numb;

void print_numb(numb* n)
{
    //print backwards
    if (n->N==0) {
        printf("0");
    } else {
        for(sint i=n->N-1; i>=0; i--) printf("%u_",n->d[i]);
    }
}

int main(void)
{
   //todo:malloc for n (Nb) and for d (Nd), maybe not needed
   numb n[MAX_BASES];  //number table for all bases
   const uint x=0xe27efc30f694;
   uint xtmp=x;
   uint Nb=0;
   uint N=0;    //number of calculated bases

   while(xtmp!=1) { //get msb bit position
       xtmp>>=1;
       Nb++;
   }

   printf("x=%u,Nb=%u:\r\n",x,Nb);

   //base is index of n
   //x mod(base-1) is in n['i'].r
   for(uint base=2; base<Nb+1; base<<=1) {   //base2^N
        uint r=0;
        uint cd=0;
        uint pos_i=log2(base);
        xtmp=x;

        printf("\r\nbase=%u:\r\n",base);

        for(int pos=0; pos<Nb; pos+=pos_i) {
            uint d=xtmp&(base-1); //get digit in base

            xtmp>>=pos_i;
            printf("N=%u,cd=%u,d=%u\r\n",N,cd,d);

            n[N].d[cd]=d;
            r+=d;   //sum of digits is remainder x mod(base-1)

            if(r>=base) r-=base-1;  //modulo sum

            cd++;
        }

        //note
        if (r==base-1) r=0; //0 equivalent to base-1 when doing mod(base-1)
        //

        n[N].N=cd;
        n[N].r=r;

        N++;
   }

   //todo: display column as base, row as digits
   printf("\r\n\Displaying all values:\r\n");
   printf("x=%u,N=%u,Nb=%u:\r\n\r\n",x,N,Nb);

   for(int i=0; i<N;i++) {
       uint base=1<<(i+1);

       printf("base%u:",base);
       print_numb(n+i);
       printf(",r=%u",n[i].r);

       if(n[i].r==x%(base-1)) printf("   ...OK\r\n");
       else printf("   ...FAILED, r=%u\r\n",x%(base-1));
   }

    return 0;
}