Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

vhdl code for state machine

Hai,

Can anyone justify what the different between two line codes below:

1) case cycle is

when 0l1l7 =>cp<=SXT(bm,11)+b3;

end case

2) if cycle=2 or cycle=3 then

cm<=SXT(b2,11)-b3;

end if

I'm curious the function of "l". Is it it mean by "AND" function? Thanks in advance

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    | in this context is just to combine several cases in one line and avoid repeating some code.

    when 0|1|7 =>cp<=SXT(bm,11)+b3;
    is equivalent to
    when 0 => cp<=SXT(bm,11)+b3;
when 1 => cp<=SXT(bm,11)+b3;
when 7 => cp<=SXT(bm,11)+b3;

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    IIRC, | can only be used in case statements or in with..select statements. It is not an "or" operator.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    Hai Daixiwen and Tricky,

    Thanks for your explanations. I understand now, very appreciates. :)