From 2ac4f3a09559a6866827404fc47be4dfe635e9d5 Mon Sep 17 00:00:00 2001
From: Nick McKinney <nick@kmonkey.net>
Date: Thu, 8 Dec 2016 22:41:56 -0600
Subject: create decoder stage

---
 decoder_stage.v | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 nqcpu.qsf       |  3 +-
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 decoder_stage.v

diff --git a/decoder_stage.v b/decoder_stage.v
new file mode 100644
index 0000000..18ed195
--- /dev/null
+++ b/decoder_stage.v
@@ -0,0 +1,86 @@
+module decoder_stage (
+	input clk,
+	input en,
+
+	input [15:0] instr_in,
+	
+	output reg [3:0] aluOp_out,
+	output reg [2:0] aluReg1_out,
+	output reg [2:0] aluReg2_out,
+	output reg [1:0] aluOpSource1_out,		// ALU first operand: 0 = reg, 1 = memory read, 2 = imm8, 3 = PC
+	output reg [1:0] aluOpSource2_out,		// ALU second operand: 0 = reg, 1 = ~reg, 2 = PC, 3 = ???
+	output reg aluDest_out,					// 0 = reg, 1 = PC
+
+	output reg [2:0] regDest_out,
+	output reg regSetH_out,
+	output reg regSetL_out,
+	
+	output reg [2:0] regAddr_out,
+	output reg memReadB_out,
+	output reg memReadW_out,
+	output reg memWriteB_out,
+	output reg memWriteW_out,
+	
+	output reg [4:0] setRegCond_out,   // {should set when condition is true, Z doesn't matter, S doesn't matter, Z must be this, S must be this}
+	
+	output reg [15:0] imm_out
+);
+
+	wire [3:0] aluOp_next;
+	wire [2:0] aluReg1_next;
+	wire [2:0] aluReg2_next;
+	wire [1:0] aluOpSource1_next;
+	wire [1:0] aluOpSource2_next;
+	wire aluDest_next;
+	wire [2:0] regDest_next;
+	wire regSetH_next;
+	wire regSetL_next;
+	wire [2:0] regAddr_next;
+	wire memReadB_next;
+	wire memReadW_next;
+	wire memWriteB_next;
+	wire memWriteW_next;
+	wire [4:0] setRegCond_next;
+	wire [15:0] imm_next;
+
+	decoder decoder_inst (
+		.instr(instr_in),
+		.aluOp(aluOp_next),
+		.aluReg1(aluReg1_next),
+		.aluReg2(aluReg2_next),
+		.aluOpSource1(aluOpSource1_next),
+		.aluOpSource2(aluOpSource2_next),
+		.aluDest(aluDest_next),
+		.regDest(regDest_next),
+		.regSetH(regSetH_next),
+		.regSetL(regSetL_next),
+		.regAddr(regAddr_next),
+		.memReadB(memReadB_next),
+		.memReadW(memReadW_next),
+		.memWriteB(memWriteB_next),
+		.memWriteW(memWriteW_next),
+		.setRegCond(setRegCond_next),
+		.imm(imm_next)
+	);
+	
+	always @(posedge clk) begin
+		if(en) begin
+			aluOp_out <= aluOp_next;
+			aluReg1_out <= aluReg1_next;
+			aluReg2_out <= aluReg2_next;
+			aluOpSource1_out <= aluOpSource1_next;
+			aluOpSource2_out <= aluOpSource2_next;
+			aluDest_out <= aluDest_next;
+			regDest_out <= regDest_next;
+			regSetH_out <= regSetH_next;
+			regSetL_out <= regSetL_next;
+			regAddr_out <= regAddr_next;
+			memReadB_out <= memReadB_next;
+			memReadW_out <= memReadW_next;
+			memWriteB_out <= memWriteB_next;
+			memWriteW_out <= memWriteW_next;
+			setRegCond_out <= setRegCond_next;
+			imm_out <= imm_next;
+		end
+	end
+endmodule
diff --git a/nqcpu.qsf b/nqcpu.qsf
index 33d9bd8..db8dcc5 100644
--- a/nqcpu.qsf
+++ b/nqcpu.qsf
@@ -38,7 +38,7 @@
 
 set_global_assignment -name FAMILY "Cyclone II"
 set_global_assignment -name DEVICE EP2C20F484C7
-set_global_assignment -name TOP_LEVEL_ENTITY alu
+set_global_assignment -name TOP_LEVEL_ENTITY decoder_stage
 set_global_assignment -name ORIGINAL_QUARTUS_VERSION "13.0 SP1"
 set_global_assignment -name PROJECT_CREATION_TIME_DATE "22:25:59  NOVEMBER 17, 2016"
 set_global_assignment -name LAST_QUARTUS_VERSION "13.0 SP1"
@@ -55,6 +55,7 @@ set_global_assignment -name VERILOG_FILE alu.v
 set_global_assignment -name VERILOG_FILE shifter.v
 set_global_assignment -name VERILOG_FILE shifter_tb.v
 set_global_assignment -name VERILOG_FILE alu_tb.v
+set_global_assignment -name VERILOG_FILE decoder_stage.v
 set_global_assignment -name PARTITION_NETLIST_TYPE SOURCE -section_id Top
 set_global_assignment -name PARTITION_FITTER_PRESERVATION_LEVEL PLACEMENT_AND_ROUTING -section_id Top
 set_global_assignment -name PARTITION_COLOR 16764057 -section_id Top
-- 
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