How to represent Integer greater than integer'high

vhdl
mbrandalero picture mbrandalero · Nov 18, 2012 · Viewed 19.5k times · Source

Is there any way to use pre-defined types from STD_LOGIC_1164 or STD_NUMERIC to represent an integer ranging from 0 to 2^32-1 ? (considering the default integer type ranges from -2^31-1 to 2^31-1)

I need to implement 32-bit counter and was looking for some way to save code using integer type instead of std_logic_vector.. Any design pattern for this ?

Or, better asked: Whats the best way to declare a 32-bit (unsigned) integer supporting the operations >/<, =, +-/ ?

Tahnks in advance

Edit1: One option I found was to declare a signal as std_logic_vector(31 downto 0), and to perform conversions when doing comparisons or +- operations.. ex: counter <= counter + std_logic_vector(unsigned(value) + 1).. Still haven't found a way to do division though (in case,for example, 1/4 of the value of counter is needed)

Answer

Brian Drummond picture Brian Drummond · Nov 18, 2012

Using the Integer types, you cannot (at least, not portably; there may be some VHDL tools that go beyond the minimum and offer a 64-bit integer)

Using IEEE.numeric_std, you can declare an Unsigned with a full 32-bit range (or 53-bit if you wish) and it should do everything you want.need, unless I misunderstand what you are asking.

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