unsigned char rotar(unsigned char buffer, int nb) {
    buffer=(buffer<<nb)|(buffer>>(8-nb));
}

unsigned char set_bit(unsigned char buffer, int nb, int val) {
   int i;
   unsigned char seteador;

   if (val=1)
	{for(i=0, seteador=00000001;i<nb;i++,seteador<<1);
        buffer=buffer|seteador;
        return buffer;}

   else if (val=0)
       {for(i=0, seteador=11111110;i<nb;i++,rotar(seteador,1));
  	    buffer=buffer&seteador;
        return buffer;}
   else
	   {printf("Introfuzca otro valor en 'val'");}
 }

int main()
{  set_bit('l',7,7); }