X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/5b3daee2fb720393ea9afbbf8647f912701b6fed..b7359a807e88320755edab8987c269a0b9c83f26:/Execute.v

diff --git a/Execute.v b/Execute.v
index 64999fa..d7b4ba6 100644
--- a/Execute.v
+++ b/Execute.v
@@ -9,15 +9,62 @@ module Execute(
 	input [31:0] pc,
 	input [31:0] insn,
 	input [31:0] cpsr,
-	input reg [31:0] op0,
-	input reg [31:0] op1,
-	input reg [31:0] op2,
-	input reg carry,
+	input [31:0] op0,
+	input [31:0] op1,
+	input [31:0] op2,
+	input carry,
 	
 	output reg outstall = 0,
 	output reg outbubble = 1,
+	output reg write_reg = 1'bx,
+	output reg [3:0] write_num = 4'bxxxx,
+	output reg [31:0] write_data = 32'hxxxxxxxx
 	);
+	
+	reg mult_start;
+	reg [31:0] mult_acc0, mult_in0, mult_in1;
+	wire mult_done;
+	wire [31:0] mult_result;
+	
+	Multiplier multiplier(
+		.clk(clk), .Nrst(Nrst),
+		.start(mult_start), .acc0(mult_acc0), .in0(mult_in0),
+		.in1(mult_in1), .done(mult_done), .result(mult_result));
+endmodule
 
+module Multiplier(
+	input clk,
+	input Nrst,	/* XXX not used yet */
+	
+	input start,
+	input [31:0] acc0,
+	input [31:0] in0,
+	input [31:0] in1,
+	
+	output reg done = 0,
+	output reg [31:0] result);
 	
+	reg [31:0] bitfield;
+	reg [31:0] multiplicand;
+	reg [31:0] acc;
 	
+	always @(posedge clk)
+	begin
+		if (start) begin
+			bitfield <= in0;
+			multiplicand <= in1;
+			acc <= acc0;
+			done <= 0;
+		end else begin
+			bitfield <= {2'b00, bitfield[31:2]};
+			multiplicand <= {multiplicand[29:0], 2'b00};
+			acc <= acc +
+				(bitfield[0] ? multiplicand : 0) +
+				(bitfield[1] ? {multiplicand[30:0], 1'b0} : 0);
+			if (bitfield == 0) begin
+				result <= acc;
+				done <= 1;
+			end
+		end
+	end
 endmodule