Re: gEDA-user: tb_ethernet.v

[Stephen Williams <steve@icarus.com>]

cfk@pacbell.net said:
> phy_data = {8'h7D, (i[7:0] + 1)};

cfk@pacbell.net said:
> tb_ethernet.v:2080 error: operand of concatenation has indefinite
> width 

See this section in the iverilog ieee1364-notes.txt with your distribution:

* UNSIZED EXPRESSIONS AS PARAMETERS TO CONCATENATION {}

In particular, the expression (i[7:0] + 1) does not do what you
expect, and in fact this is a *bug* in tb_ethernet.v. Change it
to (i[7:0] + 8'd1) and you will be much happier.

Other compilers do not complain about this, but they also don't
generally do what you expect. Some very expensive compilers believe
that the expression {8'h7D, (i[7:0] + 1)} is 40 bits (8 + 32) long,
then truncated to fit into the phys_data l-value.
-- 
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
steve at picturel.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."