X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/dadf7990cbca24581bbb3c036df717dd59bdea41..06ad3a30038ac8ca45dd7b0c34213c0c8335c17c:/Interrupt.v

diff --git a/Interrupt.v b/Interrupt.v
new file mode 100644
index 0000000..4e3d17d
--- /dev/null
+++ b/Interrupt.v
@@ -0,0 +1,50 @@
+`define ADDR_IF 16'hFF0F
+`define ADDR_IE 16'hFFFF
+
+module Interrupt(
+	input clk,
+	input rd,
+	input wr,
+	input [15:0] addr,
+	inout [7:0] data,
+	input vblank,
+	input lcdc,
+	input tovf,
+	input serial,
+	input buttons,
+	output master,
+	output [7:0] jaddr);
+
+	wire [7:0] iflag = {3'b0,buttons,serial,tovf,lcdc,vblank};
+	reg [7:0] imask = 16'hFFFF;
+	reg [7:0] ihold = 0;
+	wire [7:0] imasked = ihold & imask;
+
+	assign data = rd ?
+	                 (addr == `ADDR_IF) ? ihold :
+	                 (addr == `ADDR_IE) ? imask :
+	                 8'bzzzzzzzz :
+		      8'bzzzzzzzz;
+
+	assign master = (imasked) != 0;
+
+	assign jaddr = imasked[0] ? 8'h40 :
+		       imasked[1] ? 8'h48 :
+		       imasked[2] ? 8'h50 :
+		       imasked[3] ? 8'h58 :
+		       imasked[4] ? 8'h60 : 8'h00;
+
+	always @ (negedge clk)
+	begin
+		if (wr) begin
+			case(addr)
+			`ADDR_IF : ihold <= iflag | data;
+			`ADDR_IE : imask <= data;
+			endcase
+			
+		end
+		else
+			ihold <= ihold | iflag;
+	end
+
+endmodule