#include <stdio.h>
typedef unsigned int uint;
uint fb(uint n) {
static const unsigned char ma[] = {
   30, 30, 0, 17, 1, 4, 18, 10, 28, 2, 26,  5,  7, 19, 22, 11,
   29, 16, 3, 9, 27, 25, 6, 21, 15, 8, 24, 20, 14, 23, 13, 12};
return ma[(n*0x12CF8DD4)>>(32-5)];}

int main(){int j;
  for(j=0; j<32; ++j) if(j != fb(1<<j)) printf("error %d\n", j);
   // while(j) {printf ("%08x %d\n", j, fb(j)); j += j;}
   printf("fb(0) = %d; fb(1<<31)=%d\n", fb(0), fb(1<<31));
   return 0;}

// error 31
// fb(0) = 30; fb(1<<31)=30