[SOLVED] I found this syntax helpful. T'pos(X)

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sometimes we need to display a state machine's state on LEDs or signals.
the syntax below helps us to display the number of state machine on LEDs.

Syntax: T'pos(X) Returns the position number of X within the type T.

example:

type tState is (S1,S2,S3);
signal sMainState:tState:=S1;
signal sLeds	:std_logic_vector(2 downto 0);
....
...
sLeds	<=conv_std_logic_vector(tState'pos(sMainState),sLeds'length);

 

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Code VHDL - [expand]
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sLeds   <=conv_std_logic_vector(tState'pos(sMainState), sLeds'length);

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And here is how to do it with the standard library numeric_std:

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Code VHDL - [expand]
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sLeds   <= std_logic_vector(to_unsigned(tState'pos(sMainState),sLeds'length));

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