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Autogenerated altshift taps

Altera_Forum
Honored Contributor II
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https://alteraforum.com/forum/attachment.php?attachmentid=15412&stc=1  

 

Dear Developers, 

I am creating a code where I used memory , however there is a part of memory that I didn't actually use , it is "auto generated" called altshift taps as shown in image, Kindly I need a justification for adding it by Quartus. 

Many thanks.
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Altera_Forum
Honored Contributor II
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FPGA synthesis never implements any resource that isn't "actually used". I guess the problem is that you don't understand which part of the code infers a RAM based shift register. But without seeing the code, it's hard to tell.

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Altera_Forum
Honored Contributor II
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FPGA synthesis never implements any resource that isn't "actually used". I guess the problem is that you don't understand which part of the code infers a RAM based shift register. But without seeing the code, it's hard to tell. 

 

The hierarchy view already tells you that it's used in the implementation of dataodd_rtl. There's no additional autogenerated logic, it's just the way how altshift_taps is implemented.
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Altera_Forum
Honored Contributor II
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--- Quote Start ---  

FPGA synthesis never implements any resource that isn't "actually used". I guess the problem is that you don't understand which part of the code infers a RAM based shift register. But without seeing the code, it's hard to tell. 

 

The hierarchy view already tells you that it's used in the implementation of dataodd_rtl. There's no additional autogenerated logic, it's just the way how altshift_taps is implemented. 

--- Quote End ---  

 

 

I used data odd here : 

 

BEGIN 

IF (rising_edge (clk)) THEN 

Splitter<=Original(generaladdress); 

dataeven <= Splitter(9 downto 0); 

dataodd<=Splitter(19 downto 10); 

 

 

if kk=2 then 

First_Reg<=dataeven; 

else 

evenbuff<= dataeven; 

end if; 

xoddbuff<=dataodd; 

oddbuff<=xoddbuff; 

 

It temporary holding a value since I need to wait for one clock cycle, however, I defined it as signal of unsigned, I don't know why it used as m4k?
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Altera_Forum
Honored Contributor II
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The shown code snippet doesn't give reason to expect altshift_taps inference. I guess, i's not the full picture.

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Altera_Forum
Honored Contributor II
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There is nothing surprising here as by default the tool is made free to infer memory for some shift operations. The user can disable that in the project settings.

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Altera_Forum
Honored Contributor II
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altshift_taps is used for multicycle shift registers. But there's no respective function in the shown code snippet.

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Altera_Forum
Honored Contributor II
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--- Quote Start ---  

There is nothing surprising here as by default the tool is made free to infer memory for some shift operations. The user can disable that in the project settings. 

--- Quote End ---  

 

 

I tried to disable it here but it doesn't workhttps://www.alteraforum.com/forum/attachment.php?attachmentid=15420
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Altera_Forum
Honored Contributor II
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Thanks for reply, the only place I used that signal (dataodd) is here! How can I disable it? Regards.

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Altera_Forum
Honored Contributor II
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I don't see you have chosen the right setting.  

I believe it should be something like: Auto Shift Register Recognition OFF. 

You can also apply it specifically to your signal using attribute.
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Altera_Forum
Honored Contributor II
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I didn't notice such settings .. :(

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