Find most significant bit (left-most) that is set in a bit array

#include<stdio.h>

#define DIF_VAL (1<<15)


int find_sigbit(int *tlb,int n)
{
        int r=0;
        if(n&0xffff0000){r+=16;n>>=16;}
//      if(n&0xff00){r+=8;n>>=8;}
        return r+tlb[n];
}
int main(void)
{
int k;
int tlb[32768];
        int idx=0,idv=1,i;
        for(i=0;i<DIF_VAL;i++)
        {
                if(i>=idv)
                {
                        idx++;idv<<=1;
                }
   
                tlb[i]=idx;

        }
     /*   for(i=0;i<DIF_VAL;i++)
        {
                printf("%d ",tlb[i]);
                if((i+1)%32==0)printf("\n");
        }*/
printf("please enter a value\n");
scanf("%d",&k);
printf("k's first significant bit is %d\n",find_sigbit(tlb,k));
        return 0;
}