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Synopsys clock edge question

 
 
blarg
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      06-27-2005
I am having an issue with synthesizing the code below using Synopsys
design analyzer.

---
clkproc_12: process(clk)
begin

for index in 0 to num_stg12_sad_regs-1 loop
if (rising_edge(clk)) then
if (rst = '1' or stg12_rst(index) = '1') then
stg12_sad_reg((index+1)*out_size-1 downto
index*out_size) <= "000000000000";
elsif ((en and stg12_en(index)) = '1') then
stg12_sad_reg((index+1)*out_size-1 downto index*out_size) <=
stg1_add_out;
end if;
end if;
end loop;

end process;
--

The error that I get is:

Error: This use of clock edge specification not supported in routine PE
line 219 in file 'xxx/pe.vhd' (HDL-109)

Line 219 is the "rising_edge" line. I am not sure what is wrong with
this clock specification, is it because of it being nested in a for
loop?

Any help would be appreciated.

 
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Ralf Hildebrandt
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      06-27-2005
blarg wrote:
> I am having an issue with synthesizing the code below using Synopsys
> design analyzer.
>
> ---
> clkproc_12: process(clk)
> begin
>
> for index in 0 to num_stg12_sad_regs-1 loop
> if (rising_edge(clk)) then


Whoops - what is this?

You can eighter
* have an outside for-generate statement having inside a process, to infer a
number of similar ressources (described by the process)
XOR
* have a process beeing edge-sensitve and inside the edge-sensitve if-clause a for-loop
doing some stuff

In other words: Edge-sensitive statements are not allowed inside a for-loop by your
synthesis tool - and I guess by any other synthesis tool.


Ralf
 
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blarg
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      06-27-2005
Thanks, Ralf. for-generate worked.

 
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