From b9cb483f3e2a498ee75a422e09164a920918362b Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Wed, 3 Sep 2014 21:20:59 +0200
Subject: [PATCH] Using $pos models for $bu0

---
 backends/verilog/verilog_backend.cc | 17 +----------------
 kernel/calc.cc                      |  2 +-
 kernel/satgen.h                     |  2 +-
 3 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/backends/verilog/verilog_backend.cc b/backends/verilog/verilog_backend.cc
index d1fa55b94..79672540b 100644
--- a/backends/verilog/verilog_backend.cc
+++ b/backends/verilog/verilog_backend.cc
@@ -538,6 +538,7 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 
 	HANDLE_UNIOP("$not", "~")
 	HANDLE_UNIOP("$pos", "+")
+	HANDLE_UNIOP("$bu0", "+")
 	HANDLE_UNIOP("$neg", "-")
 
 	HANDLE_BINOP("$and",  "&")
@@ -651,22 +652,6 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 		return true;
 	}
 
-	if (cell->type == "$bu0")
-	{
-		f << stringf("%s" "assign ", indent.c_str());
-		dump_sigspec(f, cell->getPort("\\Y"));
-		if (cell->parameters["\\A_SIGNED"].as_bool()) {
-			f << stringf(" = $signed(");
-			dump_sigspec(f, cell->getPort("\\A"));
-			f << stringf(");\n");
-		} else {
-			f << stringf(" = { 1'b0, ");
-			dump_sigspec(f, cell->getPort("\\A"));
-			f << stringf(" };\n");
-		}
-		return true;
-	}
-
 	if (cell->type == "$concat")
 	{
 		f << stringf("%s" "assign ", indent.c_str());
diff --git a/kernel/calc.cc b/kernel/calc.cc
index 4048e4a1f..da03f6164 100644
--- a/kernel/calc.cc
+++ b/kernel/calc.cc
@@ -575,7 +575,7 @@ RTLIL::Const RTLIL::const_pow(const RTLIL::Const &arg1, const RTLIL::Const &arg2
 RTLIL::Const RTLIL::const_pos(const RTLIL::Const &arg1, const RTLIL::Const&, bool signed1, bool, int result_len)
 {
 	RTLIL::Const arg1_ext = arg1;
-	extend(arg1_ext, result_len, signed1);
+	extend_u0(arg1_ext, result_len, signed1);
 
 	return arg1_ext;
 }
diff --git a/kernel/satgen.h b/kernel/satgen.h
index c7f1680d4..eed3adaad 100644
--- a/kernel/satgen.h
+++ b/kernel/satgen.h
@@ -470,7 +470,7 @@ struct SatGen
 			{
 				std::vector<int> undef_a = importUndefSigSpec(cell->getPort("\\A"), timestep);
 				std::vector<int> undef_y = importUndefSigSpec(cell->getPort("\\Y"), timestep);
-				extendSignalWidthUnary(undef_a, undef_y, cell, cell->type != "$bu0");
+				extendSignalWidthUnary(undef_a, undef_y, cell);
 
 				if (cell->type == "$pos" || cell->type == "$bu0") {
 					ez->assume(ez->vec_eq(undef_a, undef_y));
-- 
2.30.2