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Altera_Forum's avatar
Altera_Forum
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8 years ago

Verilog $display(" ") equivalent/does not compile in VHDL ?

Hello,

I have been looking for the equivalent of the $display("") command in VHDL for some time now:

main_clock: process

begin

CLK_CPU<='1';

wait for TClock/2;

$display("test "); --error

CLK_CPU<='0';

wait for TClock/2;

end process;

What ever i do the lines above do not compile. (see bold)

** Error: C:/FpgaProjects/Q17/DE2_115_Shark_Serial_Component/main_bench.vhd(33): near "$": syntax error

Should i include a library or is there a modelsim setting i need to change ?

Lots of documents are available about the different possible parameters and Modelsim tutorials,

the answer to this rather basic question i could not find.

Thanks for any help,

Johi.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    There are really two answers to this. You can either use the report statement:

    report "test";

    or you can use the textio library. 

    
use std.textio.all;
....
write(OUTPUT, "test" & LF);  -- test and line-feed

    OUTPUT is a built in file that is the system console. There are many tutorials out there on how to use textio.

    VHDL does not have equivolents of the Verilog System Calls (that start with $).
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    You cannot use Verilog/SV system tasks in VHDL. Both are different languages. In VHDL you can use the write () function to write values to console during simulation. Use the IEEE textio package and then call the write ( ) function. 

    
Use Std.textio.all;
..
..
write ( ) ; -- write values to display
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    8 years ago

    Hello Tricky & eapenabrm,

    Tanks for the answer, I read about write & textio, thought this was reserved for disk file io.

    Never thought about the OUTPUT stream.

    Best Regards,

    Johi.