Determine which single bit in the byte is set

Question

I have a byte I\'m using for bitflags. I know that one and only one bit in the byte is set at any give time.

Ex:

Answer 1

unsigned getSetBitLocation(unsigned char b) {
  unsigned pos=0;
  pos = (b & 0xf0) ? 4 : 0; b |= b >>4;
  pos += (b & 0xc) ? 2 : 0; b |= b >>2;
  pos += (b & 0x2) ? 1 : 0; 
  return pos; 
}

It would be hard to do it jumpfree. Maybe with the Bruin sequences ?

Answer 2

if you define

const char bytes[]={1,2,4,8,16,32,64,128}

and use

struct byte{
char data;
int pos;
}
void assign(struct byte b,int i){

b.data=bytes[i];
b.pos=i
}

you don't need to determine the position of the set bit