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-rw-r--r--techlibs/xilinx/synth_xilinx.cc30
1 files changed, 14 insertions, 16 deletions
diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index c18c3918f..f43923afb 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -280,23 +280,21 @@ struct SynthXilinxPass : public ScriptPass
}
else if (widemux > 0) {
run("simplemap t:$mux");
- std::string muxcover_args = " -nodecode";
+ constexpr int cost_mux2 = 100;
+ std::string muxcover_args = stringf(" -nodecode -mux2=%d", cost_mux2);
switch (widemux) {
- // NB: Cost of mux2 is 100; mux8 should cost between 3 and 4
- // of those so that 4:1 muxes and below are implemented
- // out of mux2s
- case 5: muxcover_args += " -mux8=350 -mux16=400"; break;
- case 6: muxcover_args += " -mux8=450 -mux16=500"; break;
- case 7: muxcover_args += " -mux8=550 -mux16=600"; break;
- case 8: muxcover_args += " -mux8=650 -mux16=700"; break;
- case 9: muxcover_args += " -mux16=750"; break;
- case 10: muxcover_args += " -mux16=850"; break;
- case 11: muxcover_args += " -mux16=950"; break;
- case 12: muxcover_args += " -mux16=1050"; break;
- case 13: muxcover_args += " -mux16=1150"; break;
- case 14: muxcover_args += " -mux16=1250"; break;
- case 15: muxcover_args += " -mux16=1350"; break;
- default: muxcover_args += " -mux16=1450"; break;
+ case 5:
+ case 6:
+ case 7:
+ case 8: muxcover_args += stringf(" -mux8=%d -mux16=%d", cost_mux2*(widemux-1)-1, cost_mux2*(widemux-1)); break;
+ case 9:
+ case 10:
+ case 11:
+ case 12:
+ case 13:
+ case 14:
+ case 15:
+ default: muxcover_args += stringf(" -mux16=%d", cost_mux2*(widemux-1)-1); break;
}
run("muxcover " + muxcover_args);
}