Question about conditional generate

[cathy]

Hello, All.

I have a question about the conditional generate statement.
For my code:

constant C_BankNumBits : Natural :=1;
constant C_BankNum :Natural := 2**(C_BankNumBits);

G_RegBank1 : if(C_BankNumBits=0) generate
G_RegBank : for i in 0 to (C_BankNum-1) generate
RegBank : brb8
port map (
clka => clk, dina => dina(i), addra => addra,
wea => wea, douta => douta(i),
clkb => clk, dinb => dinb(i), addrb => addrb,
web => web, doutb => doutb(i));
end generate G_RegBank;
end generate G_RegBank1;

....... other generate statement......
(here, I want to use different memory size if different bank number is
used)

I defined addra as std_logic_vector(11-C_BankNumBits downto 0).
Addra in the component brb8 is (11 downto 0).
In this case, I think the above generate statement won't work because
it doesn't satisfy the conidtion: if(C_BankNumBits=0). But the ISE give
me the following error when I check the syntax:
"Width mismatch. Expected width 12, Actual width is 11 for dimension 1
of addra."

Can anybody explains this to me?

Thanks a lot,
Cathy

 

[Andy]

You assume that c_banknumbits is 0 in the first assumption, yet it is
defined as 1.

Even though the generate statement is not elaborated, the width
checking is done at analysis (compile) time, which means that it must
be valid even if the generate statement turns out not to be elaborated.

Andy

 

[cathy]

Thank you very much for your help,
Cathy