Hello
I am trying to write a binary result file in vhdl.
I tried to write with type character, with narural ranged 0-255,
with array of 8bits but i never had the expected result.
(i expect to write 1 byte)
In most simulators, "file of character" works OK. Precisely
what features of the result were unexpected?
The following process gives me a binary file containing
256 bytes, with values 0, 1, 2, ... 254, 255.
process
type charfile is file of character;
file f: charfile;
begin
file_open(f, "junk.bin", write_mode);
for i in 0 to 255 loop
write(f, character'val(i));
end loop;
file_close(f);
wait;
end process;
Strictly, this code is not portable across simulators and
operating systems. In practice, though, it works well.
Trying to write a file of "natural range 0 to 255" is
much less likely to work, because "natural range 0 to 255"
is a subtype of integer and therefore each object probably
occupies 32 bits. You can write files like this, with each
32-bit integer representing 4 bytes, but you are then at the
mercy of byte ordering conventions and suchlike.
--
Jonathan Bromley, Consultant
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