From 10589c57bfd0e5dd29c739e9d9db044cdb8ad8ed Mon Sep 17 00:00:00 2001
From: Miodrag Milanovic <mmicko@gmail.com>
Date: Fri, 17 Mar 2023 16:15:43 +0100
Subject: insert IO buffers for ECP5, off by default

---
 techlibs/ecp5/synth_ecp5.cc | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index f2dc534f9..82e234868 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -100,6 +100,9 @@ struct SynthEcp5Pass : public ScriptPass
 		log("        generate an output netlist (and BLIF file) suitable for VPR\n");
 		log("        (this feature is experimental and incomplete)\n");
 		log("\n");
+		log("    -iopad\n");
+		log("        insert IO buffers\n");
+		log("\n");
 		log("    -nodsp\n");
 		log("        do not map multipliers to MULT18X18D\n");
 		log("\n");
@@ -115,7 +118,7 @@ struct SynthEcp5Pass : public ScriptPass
 	}
 
 	string top_opt, blif_file, edif_file, json_file;
-	bool noccu2, nodffe, nobram, nolutram, nowidelut, asyncprld, flatten, dff, retime, abc2, abc9, nodsp, vpr, no_rw_check;
+	bool noccu2, nodffe, nobram, nolutram, nowidelut, asyncprld, flatten, dff, retime, abc2, abc9, iopad, nodsp, vpr, no_rw_check;
 
 	void clear_flags() override
 	{
@@ -135,6 +138,7 @@ struct SynthEcp5Pass : public ScriptPass
 		abc2 = false;
 		vpr = false;
 		abc9 = false;
+		iopad = false;
 		nodsp = false;
 		no_rw_check = false;
 	}
@@ -223,6 +227,10 @@ struct SynthEcp5Pass : public ScriptPass
 				abc9 = true;
 				continue;
 			}
+			if (args[argidx] == "-iopad") {
+				iopad = true;
+				continue;
+			}
 			if (args[argidx] == "-nodsp") {
 				nodsp = true;
 				continue;
@@ -319,6 +327,11 @@ struct SynthEcp5Pass : public ScriptPass
 				run("techmap");
 			else
 				run("techmap -map +/techmap.v -map +/ecp5/arith_map.v");
+			if (help_mode || iopad) {
+				run("iopadmap -bits -outpad OB I:O -inpad IB O:I -toutpad OBZ ~T:I:O -tinoutpad BB ~T:O:I:B A:top", "(only if '-iopad')");
+				run("attrmvcp -attr src -attr LOC t:OB %x:+[O] t:OBZ %x:+[O] t:BB %x:+[B]");
+				run("attrmvcp -attr src -attr LOC -driven t:IB %x:+[I]");
+			}
 			run("opt -fast");
 			if (retime || help_mode)
 				run("abc -dff -D 1", "(only if -retime)");
-- 
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