Addition problem in Quartus

Be aware that, with ieee.numeric_std, 32bits_vector + 32bits_vector = 32bits_vector the 33th bit (which is carry) is simply forgotten I have already face to : http://www.alteraforum.com/forum/showthread.php?t=21027&p=180870#post180870

In standard package, Integers are numbers from –2147483648 to +2147483647 (Be carefull dwh@ovro.caltech.edu ;-))

Be aware in

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async : process(subIncRot, subSubRot)

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Quartus will ignore the sensitivity list (= (subIncRot, subSubRot)), and take as sensitivity all "input" signals.

In your case, it doesn't change the behaviour.

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UNSIGNED(buffRot) is a 32-bit unsigned value

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Wrong, UNSIGNED(buffRot) will give exactly the same vector, it is just interpreted as unsigned for operations (mostly comparisons, multiplications)

BUT "TO_INTEGER" gives a 32bits vector by the compiler.