X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/b7359a807e88320755edab8987c269a0b9c83f26..96f7e6e169cb1471891980770630f3bed700c604:/Execute.v?ds=inline

diff --git a/Execute.v b/Execute.v
index d7b4ba6..b1e9df5 100644
--- a/Execute.v
+++ b/Execute.v
@@ -16,6 +16,7 @@ module Execute(
 	
 	output reg outstall = 0,
 	output reg outbubble = 1,
+	output reg [31:0] outcpsr = 0,
 	output reg write_reg = 1'bx,
 	output reg [3:0] write_num = 4'bxxxx,
 	output reg [31:0] write_data = 32'hxxxxxxxx
@@ -26,10 +27,21 @@ module Execute(
 	wire mult_done;
 	wire [31:0] mult_result;
 	
+	wire [31:0] alu_in0, alu_in1;
+	wire [3:0] alu_op;
+	wire alu_setflags, alu_set;
+	wire [31:0] alu_result, alu_outcpsr;
+	
 	Multiplier multiplier(
 		.clk(clk), .Nrst(Nrst),
 		.start(mult_start), .acc0(mult_acc0), .in0(mult_in0),
 		.in1(mult_in1), .done(mult_done), .result(mult_result));
+	
+	ALU alu(
+		.clk(clk), .Nrst(Nrst),
+		.in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op),
+		.setflags(alu_setflags), .shifter_carry(carry),
+		.result(alu_result), .cpsr_out(alu_outcpsr), .set(alu_set));
 endmodule
 
 module Multiplier(
@@ -68,3 +80,122 @@ module Multiplier(
 		end
 	end
 endmodule
+
+/* XXX is the interface correct? */
+module ALU(
+	input clk,
+	input Nrst,	/* XXX not used yet */
+
+	input [31:0] in0,
+	input [31:0] in1,
+	input [31:0] cpsr,
+	input [3:0] op,
+	input setflags,
+	input shifter_carry,
+
+	output reg [31:0] result,
+	output reg [31:0] cpsr_out,
+	output reg set
+);
+	wire [31:0] res;
+	wire flag_n, flag_z, flag_c, flag_v, setres;
+	wire [32:0] sum, diff, rdiff;
+
+	assign sum = {1'b0, in0} + {1'b0, in1};
+	assign diff = {1'b0, in0} - {1'b0, in1};
+	assign rdiff = {1'b0, in1} + {1'b0, in0};
+
+	/* TODO XXX flag_v not set correctly */
+	always @(*) begin
+		res = 32'hxxxxxxxx;
+		setres = 1'bx;
+		flag_c = cpsr[`CPSR_C];
+		flag_v = cpsr[`CPSR_V];
+		case(op)
+		`ALU_AND: begin
+			res = in0 & in1;
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		`ALU_EOR: begin
+			res = in0 ^ in1;
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		`ALU_SUB: begin
+			{flag_c, res} = diff;
+			setres = 1'b1;
+		end
+		`ALU_RSB: begin
+			{flag_c, res} = rdiff;
+			setres = 1'b1;
+		end
+		`ALU_ADD: begin
+			{flag_c, res} = sum;
+			setres = 1'b1;
+		end
+		`ALU_ADC: begin
+			{flag_c, res} = sum + {32'b0, cpsr[`CPSR_C]};
+			setres = 1'b1;
+		end
+		`ALU_SBC: begin
+			{flag_c, res} = diff - {32'b0, (~cpsr[`CPSR_C])};
+			setres = 1'b1;
+		end
+		`ALU_RSC: begin
+			{flag_c, res} = rdiff - {32'b0, (~cpsr[`CPSR_C])};
+			setres = 1'b1;
+		end
+		`ALU_TST: begin
+			res = in0 & in1;
+			flag_c = shifter_carry;
+			setres = 1'b0;
+		end
+		`ALU_TEQ: begin
+			res = in0 ^ in1;
+			flag_c = shifter_carry;
+			setres = 1'b0;
+		end
+		`ALU_CMP: begin
+			{flag_c, res} = diff;
+			setres = 1'b0;
+		end
+		`ALU_CMN: begin
+			{flag_c, res} = sum;
+			setres = 1'b0;
+		end
+		`ALU_ORR: begin
+			res = in0 | in1;
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		`ALU_MOV: begin
+			res = in1;
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		`ALU_BIC: begin
+			res = in0 & (~in1);
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		`ALU_MVN: begin
+			res = ~in1;
+			flag_c = shifter_carry;
+			setres = 1'b1;
+		end
+		endcase
+	end
+
+	always @(*) begin
+		flag_z = (res == 0);
+		flag_n = res[31];
+	end
+
+	always @(posedge clk) begin
+		result <= res;
+		cpsr_out <= setflags ? {flag_n, flag_z, flag_c, flag_v, cpsr[27:0]} : cpsr;
+		set <= setres;
+	end
+
+endmodule