On Thu, 23 Sep 2010, Stefan Hajnoczi wrote: > The get_bits_from_size() calculates the log base-2 of a number. This is > useful in bit manipulation code working with power-of-2s. > > Currently used by qcow2 and needed by qed in a follow-on patch.
int ilog2 (size_t size)
{
if (size & (size - 1))
return -1;
return __builtin_ctzl (size);
}
Ifdef WIN64 omitted for brevity.
[..snip..]
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