Honored ContributorHello,
I have a large shift-register that is being optimized by the synthesizer into a megafunction equivalent. The problem is, I need this register to stay a register (DFFs). Is there a way to turn-off this optimization? Thanks!
Honored Contributoryes.
go assignments -> settings -> analysis and synthesis settings -> more settings There is a setting called "auto shift register placements". Change this to "off". be wary though - these are global settings. I think these settings can be assigned to individual entites via assignments.Honored ContributorRight click on the hierarchy and Locate -> Assignment Editor. Copy and paste the name from the top filter bar to the To column. Auto Shift Register Replacement is the assignment again.
Honored ContributorThe global assignment worked - but trying to assign this rule to a specific part of the design did not.
I found the collection of registers that I need to apply the rule to via the drop-down menu in the 'To' textbox. I filtered on 'Registers: pre-synthesis' and added the name this way. The collection always has a question mark by it, and the tooltip says that the name is not recognized (which seems odd, because I got the name from the drop-down list). I've uploaded an image of this to google docs for reference: https://docs.google.com/open?id=0b4wyejzmihtnzmnkued6aevhrnc Any ideas? Thanks!Honored ContributorIt's possible by synthesis attributes, as discussed in a different thread http://www.alteraforum.com/forum/showthread.php?p=155649
reg data = 6000'b0 /* synthesis altera_attribute = "-name AUTO_SHIFT_REGISTER_RECOGNITION OFF" */;
