On Tue, Feb 17, 2009 at 1:38 PM, Sylvere Teissier <[email protected]> wrote:
> Peter LaDow wrote:
>> I have a module that fails during elaboration with the following message:
>>
>> uart_t0.o: In function `work__uart_t0__ARCH__behav__uart_file_con__PROC':
>> uart_t0.vhd:(.text+0x379c): undefined reference to `__ghdl_value_e8'
>> collect2: ld returned 1 exit status
>> ghdl: compilation error
>>
> It seems your code use a 'value attribute on enumerated type (bit,
> std_logic, custom ...)
I do use 'value. I'm using it to convert a string to an enumerated type, i.e.:
type enuma ( a, b, c, d );
variable tmp : enuma;
enuma := enuma'value("a");
enuma := enuma'value("b");
enuma := enuma'value("c");
enuma := enuma'value("d");
> According to ghdl source code, 'value attribute is only implemented for
> integer
>
> There are easy workarounds to not use "value" attribute and I'm curious
> of what kind of code use it (it's not synthetizable).
You are right, this is not synthesizable. It is a testbench module.
I have a command file that looks something like:
wait 10
read 5
wait 3
read 7
I have VHDL to parse the command file and puts each token (whitespace
separated) into a string. I then run through the command file
executing the commands. For example:
type cmds is (read, wait, ...);
type str_ptr is access string;
type token_array is array(natural range <>) of str_ptr;
type token_array_ptr is access token_array;
type token_list is array (natural range <>) of token_array_ptr;
process
variable tokens : token_list;
procedure parse_file(fname : in string) is
begin
...
end procedure parse_file;
variable cmdline : token_array_ptr;
begin
-- Parse the file into the tokens variable
parse_file(CMD_FILENAME);
for i in tokens'range loop
cmdline := tokens(i);
case cmds'value(cmdline(0).all) is
when read =>
when wait =>
end case;
end loop;
end process;
Where parse_file() parses into the tokens variable.
Now, I'm sure I can replace the case/end case with an if/elsif/endif
chain, and that would work. I didn't know that GHDL didn't support
'value for enumerated types.
I admit that I first implemented this in Modelsim, and it works there.
I'm trying to port these testbench modules over to GHDL.
Thanks,
Pete
--
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