[PROG CHALLENGE #024] Non-Corporate Edition

Write a function:

int solution(int N);

that, given a positive integer N, returns the length of its longest binary gap. The function should return 0 if N doesn't contain a binary gap.

For example, given N = 1041 the function should return 5, because N has binary representation 10000010001 and so its longest binary gap is of length 5. Given N = 32 the function should return 0, because N has binary representation '100000' and thus no binary gaps.

; in: ecx
; out:eax
solution:
xor edx, edx
L1:
shr ecx, 1
jz _ret
jnc L1
xchg eax, ecx
L2:
bsf ecx, eax
cmp ecx, edx
cmova edx, ecx
inc ecx
shr eax, cl
jnz L2
_ret:
xchg eax, edx
ret

24 bytes. It's funny how all the HLL solutions posted above are larger both in source and binary form... so much for HLLs being efficient!