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From: | malc |
Subject: | Re: [Qemu-devel] [PATCH 1/7] qcow2: Make get_bits_from_size() common |
Date: | Fri, 24 Sep 2010 01:50:39 +0400 (MSD) |
User-agent: | Alpine 2.00 (LNX 1167 2008-08-23) |
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..] -- mailto:address@hidden
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