From 11789db206276edf50f45f8d82e094a87643630c Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Thu, 14 Mar 2013 11:15:00 +0100
Subject: [PATCH] More support code for $sr cells

---
 backends/verilog/verilog_backend.cc | 30 ++++++++++++++++++++++++++++-
 techlibs/simlib.v                   | 21 ++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/backends/verilog/verilog_backend.cc b/backends/verilog/verilog_backend.cc
index 7d6c75150..613324b16 100644
--- a/backends/verilog/verilog_backend.cc
+++ b/backends/verilog/verilog_backend.cc
@@ -143,7 +143,7 @@ bool is_reg_wire(RTLIL::SigSpec sig, std::string &reg_name)
 		if (sig.width == 1)
 			reg_name += stringf("[%d]", sig.chunks[0].wire->start_offset +  sig.chunks[0].offset);
 		else
-			reg_name += stringf("[%d]", sig.chunks[0].wire->start_offset +  sig.chunks[0].offset + sig.chunks[0].width - 1,
+			reg_name += stringf("[%d:%d]", sig.chunks[0].wire->start_offset +  sig.chunks[0].offset + sig.chunks[0].width - 1,
 					sig.chunks[0].wire->start_offset +  sig.chunks[0].offset);
 	}
 	return true;
@@ -556,6 +556,33 @@ bool dump_cell_expr(FILE *f, std::string indent, RTLIL::Cell *cell)
 		return true;
 	}
 
+	if (cell->type == "$sr")
+	{
+		RTLIL::SigSpec sig_set, sig_reset;
+
+		std::string reg_name = cellname(cell);
+		bool out_is_reg_wire = is_reg_wire(cell->connections["\\Q"], reg_name);
+
+		if (!out_is_reg_wire)
+			fprintf(f, "%s" "reg [%d:0] %s;\n", indent.c_str(), cell->parameters["\\WIDTH"].as_int()-1, reg_name.c_str());
+
+		fprintf(f, "%s" "always @*\n", indent.c_str());
+
+		fprintf(f, "%s" "    %s <= (%s | ", indent.c_str(), reg_name.c_str(), reg_name.c_str());
+		dump_cell_expr_port(f, cell, "S", false);
+		fprintf(f, ") & ~");
+		dump_cell_expr_port(f, cell, "R", false);
+		fprintf(f, ";\n");
+
+		if (!out_is_reg_wire) {
+			fprintf(f, "%s" "assign ", indent.c_str());
+			dump_sigspec(f, cell->connections["\\Q"]);
+			fprintf(f, " = %s;\n", reg_name.c_str());
+		}
+
+		return true;
+	}
+
 	// FIXME: $memrd, $memwr, $mem, $fsm
 
 	return false;
@@ -891,6 +918,7 @@ struct VerilogBackend : public Backend {
 
 		reg_ct.clear();
 		reg_ct.setup_stdcells_mem();
+		reg_ct.cell_types.insert("$sr");
 		reg_ct.cell_types.insert("$dff");
 		reg_ct.cell_types.insert("$adff");
 
diff --git a/techlibs/simlib.v b/techlibs/simlib.v
index 179242541..29c13503b 100644
--- a/techlibs/simlib.v
+++ b/techlibs/simlib.v
@@ -642,6 +642,27 @@ endmodule
 
 // --------------------------------------------------------
 
+module \$sr (S, R, Q);
+
+parameter WIDTH = 0;
+
+input CLK;
+input [WIDTH-1:0] S, R;
+output reg [WIDTH-1:0] Q;
+
+integer i;
+always @(S, R)
+	for (i = 0; i < WIDTH; i = i+1) begin
+		if (R[i])
+			Q[i] <= 0;
+		else if (S[i])
+			Q[i] <= 1;
+	end
+
+endmodule
+
+// --------------------------------------------------------
+
 module \$dff (CLK, D, Q);
 
 parameter WIDTH = 0;