1 files changed, 112 insertions, 0 deletions
diff --git a/rtl/src/verilog/core_selector.v b/rtl/src/verilog/core_selector.v
new file mode 100644
index 0000000..2db2a05
--- /dev/null
+++ b/rtl/src/verilog/core_selector.v
@@ -0,0 +1,112 @@
+`timescale 1ns / 1ps
+
+module core_selector
+	(
+		sys_clk, sys_rst,
+		sys_eim_addr, sys_eim_wr, sys_eim_rd,
+		sys_eim_dout, sys_eim_din
+	);
+
+		//
+		// Ports 
+		//
+	input		wire				sys_clk;
+	input		wire				sys_rst;
+	
+	input		wire	[13: 0]	sys_eim_addr;
+	input		wire				sys_eim_wr;
+	input		wire				sys_eim_rd;
+	input		wire	[31: 0]	sys_eim_dout;
+	output	wire	[31: 0]	sys_eim_din;
+
+
+		//
+		// Internal Registers
+		//
+	reg	[31: 0]	reg_x					= {32{1'b0}};
+	reg	[31: 0]	reg_y					= {32{1'b0}};
+	reg	[15: 0]	reg_ctl				= {16{1'b0}};
+	reg	[31: 0]	sys_eim_din_reg	= {32{1'b0}};
+	
+	
+		//
+		// Parameters
+		//
+	localparam	ADDER_BASE_ADDR		= 12'h321;	// upper 12 bits of address
+	localparam	ADDER_OFFSET_REG_X	= 2'd0;		// X
+	localparam	ADDER_OFFSET_REG_Y	= 2'd1;		// Y
+	localparam	ADDER_OFFSET_REG_Z	= 2'd2;		// Z
+	localparam	ADDER_OFFSET_REG_SC	= 2'd3;		// {STATUS, CONTROL}
+
+
+		/* This flag detects whether adder core is being addressed. */
+	wire eim_access_adder	= (sys_eim_addr[13:2] == ADDER_BASE_ADDR) ? 1'b1 : 1'b0;
+	
+		/* These flags detect whether write or read access is requested. */
+	wire eim_access_write	= sys_eim_wr & eim_access_adder;
+	wire eim_access_read		= sys_eim_rd & eim_access_adder;
+		
+		
+		//
+		// Write Request Handler
+		//
+	always @(posedge sys_clk)
+		//
+		if (sys_rst) begin
+			reg_x					<= {32{1'b0}};
+			reg_y					<= {32{1'b0}};
+			reg_ctl				<= {16{1'b0}};
+		end else if (eim_access_write) begin
+			//
+			case (sys_eim_addr[1:0])
+				ADDER_OFFSET_REG_X:		reg_x		<= sys_eim_dout;
+				ADDER_OFFSET_REG_Y:		reg_y		<= sys_eim_dout;
+				ADDER_OFFSET_REG_SC:		reg_ctl	<= sys_eim_dout[15: 0];
+			endcase
+			//
+		end
+
+
+		//
+		// Read Request Handler
+		//
+	wire	[31: 0]	reg_z;
+	wire	[15: 0]	reg_sts;
+	
+	always @(posedge sys_clk)
+		//
+		if (sys_rst)					sys_eim_din_reg	<= {32{1'b0}};
+		//
+		else if (eim_access_read) begin
+			//
+			case (sys_eim_addr[1:0])
+				ADDER_OFFSET_REG_X:	sys_eim_din_reg	<= reg_x;
+				ADDER_OFFSET_REG_Y:	sys_eim_din_reg	<= reg_y;
+				ADDER_OFFSET_REG_Z:	sys_eim_din_reg	<= reg_z;
+				ADDER_OFFSET_REG_SC:	sys_eim_din_reg	<= {reg_sts, reg_ctl};
+			endcase
+			//
+		end
+		
+	assign sys_eim_din = sys_eim_din_reg;
+	
+	
+		//
+		// Demo Adder Core
+		//
+	demo_adder adder_core
+	(
+		.clk	(sys_clk),
+		.rst	(sys_rst),
+		
+		.x		(reg_x),
+		.y		(reg_y),
+		.z		(reg_z),
+		
+		.ctl	(reg_ctl),
+		.sts	(reg_sts)
+	);
+	
+	
+
+endmodule