Byte swap on float and double truncates values
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Key: AMQCPP-41
URL: https://issues.apache.org/activemq/browse/AMQCPP-41
Project: ActiveMQ C++ Client
Issue Type: Bug
Affects Versions: 1.1
Reporter: Albert Strasheim
Assigned To: Nathan Mittler
Priority: Critical
Fix For: 1.1
Attachments: doublefloat-truncate.diff
activemq::util::Endian::byteSwap truncates float and double values due to the
C-style cast it uses.
Patch for BytesMessageCommandTest is attached that shows the problem. One might
consider expanding this test to check that the minimum, maximum, -1, 0, 1 (and
-inf and inf where appropriate) and a few other values can successfully be
serialised and deserialised for each of the types.
Also in the patch is our attempt at fixing byteSwap. You'll notice that we do
something very strange: we take the argument of byteSwap and make a copy on the
heap. The reason for this is that simply doing:
{noformat}
const uintxx_t swapped_val = byteSwap( *(uintxx_t*)(&value) );
{noformat}
i.e. taking the address of value instead of using the copy on the heap, fails
with GCC 4.0.2 and GCC 4.0.3. I'm guessing GCC might be trying to inline the
call to byteSwap and then something goes very wrong when taking the address of
a variable on the stack. Hopefully someone has a better idea for a workaround.
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