What does this coding do ?

[thecoder]

Hi,

Can anyone tell me what this bit of code is doing ?

-- declarations
-------------------------------------------------------------------------------------------
signal phase : std_logic_vector(6 downto 0);

type INTEGER_ARRAY is array ( natural range <> ) of integer;

constant NUMERATOR : INTEGER_ARRAY(7 downto 0) := (7,30,7,7, 30, 30, 30,30);

variable phase_next : std_logic_vector(6 downto 0);
--------------------------------------------------------------------------------------------

-- **** problem code **********

phase_next := phase + NUMERATOR(conv_integer(std));

Obviously the conv_integer(std) part of the code is being used to access the array NUMERATOR but I don't understand exactly how since no number value is being specified to key into the array.

Thanks

 

[Gunship]

What does this do ?

If you look at the end of the constant NUMERATOR line, you will see that is has a series of numbers. Those are the value inside the array. For example, NUMERATOR(0) will return a 7, NUMERATOR(1) will return 30, etc.

std probably is a std_logic_vector. That is why it needs a conv_integer since the array index has to be an integer.

I am not sure which part of the code you don't understand but I hope this help.