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17268 Discussions

ALTSHIFT_TAPS megafunction in Quartus II 9.1

Altera_Forum
Honored Contributor II
1,671 Views

Hi, 

 

Does Quartus II 9.1 Web Edition supports SHIFT_TAPS mega function. I could not find it in the mega functions wizard list.  

 

I am trying to create a long shift register.  

 

Regards
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Altera_Forum
Honored Contributor II
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What device are you targeting? It should be in there.  

Note that Quartus synthesis does an excellent job of finding shift-registers and inferring altshift_taps, so there generally isn't any reason to manually instantiate the megafunction. The one thing to avoid in the RTL is a clear on the shift register(asynchronous or synchronous) since the memory block can't have its contents cleared in one cycle. I think altshift_taps inference has a way around this, but it's probably better to avoid the clear if you can(and most shift-registers can).
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Altera_Forum
Honored Contributor II
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I am targeting Cyclone III EP3C25F324C8. If synthesis tool automatically infers ALTSHIFT_TAPS for shift registers, It should be captured in some report file. Which report file should I look for.  

 

 

Thanks
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Altera_Forum
Honored Contributor II
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I am a bit unsure about your issue. 

shift registers are not a hardwired case to be inferred like say multipliers. 

Unless you mean shift implemented in ram. In that case you can look at resource section of fitter (resource by entity)
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Altera_Forum
Honored Contributor II
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The .map.rpt has it. Just search on "altshift". I believe there is a message when inferred, there is a section on inferred megafunctions, and it will be in the hierarchy section.

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