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AR# 37730

Virtex-6, Virtex-5 - Is it possible to place more that one SRL16 in to a single SLICE?


When Iimplement a design with many SRL16s, it appears that there is only one per SLICE. Is it possible to place multiple SRL16s into the same SLICE?


It is possible to place up to four SRL16s in a single SLICE. The tools do not perform this automatically, so the SRL16s need to be constrained by either using a BEL constraint:

INST "SRL16E_inst*" LOC = "SLICE_X36Y35"; # LOC these instances to the same slice

INST "SRL16E_inst0" BEL = A6LUT;
INST "SRL16E_inst1" BEL = B6LUT;
INST "SRL16E_inst2" BEL = C6LUT;
INST "SRL16E_inst3" BEL = D6LUT;

Or, an AREA_GROUP (this can also be performed in the PlanAhead toolusing a "pblock"):

INST "SRL16E_inst0" AREA_GROUP = "pblock_SRL16E_inst0";
INST "SRL16E_inst1" AREA_GROUP = "pblock_SRL16E_inst0";
AR# 37730
Date 12/15/2012
Status Active
Type General Article
  • Virtex-6 CXT
  • Virtex-6 HXT
  • Virtex-6 LX
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