X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/45fa96c0a2fd6e490690cff69dd694a3dce3ab35..1783621cc5b0d6411aa33cf9961b29f8e440e605:/Fetch.v?ds=inline

diff --git a/Fetch.v b/Fetch.v
index 0a18b31..918e53c 100644
--- a/Fetch.v
+++ b/Fetch.v
@@ -10,32 +10,51 @@ module Fetch(
 	input stall,
 	input jmp,
 	input [31:0] jmppc,
-	output wire bubble,
-	output wire [31:0] insn,
-	output reg [31:0] pc);
-
-	reg [31:0] prevpc;
-	initial
-		prevpc = 32'hFFFFFFFC;	/* ugh... the first pc we request will be this +4 */
-	always @(negedge Nrst)
-		prevpc <= 32'hFFFFFFFC;
+	output reg bubble = 1,
+	output reg [31:0] insn = 0,
+	output reg [31:0] pc = 32'hFFFFFFFC);
+	
+	reg qjmp = 0;	/* A jump has been queued up while we were waiting. */
+	reg [31:0] qjmppc;
+	always @(posedge clk)
+		if ((rd_wait || stall) && jmp)
+			{qjmp,qjmppc} <= {jmp, jmppc};
+		else if (!rd_wait && !stall && qjmp)	/* It has already been intoed. */
+			{qjmp,qjmppc} <= {1'b0, 32'hxxxxxxxx};
 	
+	reg [31:0] reqpc;
 	always @(*)
-		if (!Nrst)
-			pc = 32'hFFFFFFFC;
-		else if (stall)	/* don't change any internal state */
-			pc = prevpc;
+		if (stall)
+			reqpc = pc;
+		else if (qjmp)
+			reqpc = qjmppc;
 		else if (jmp)
-			pc = jmppc;
+			reqpc = jmppc;
 		else
-			pc = prevpc + 32'h4;
+			reqpc = pc + 4;
+	
+	assign rd_addr = reqpc;
+	assign rd_req = 1;
+	
+	always @(negedge Nrst)
+	begin
+		pc <= 32'hFFFFFFFC;
+		qjmp <= 0;
+		bubble <= 1;
+	end
 	
-	assign bubble = stall | rd_wait;
-	assign rd_addr = pc;
-	assign rd_req = !stall;
-	assign insn = rd_data;
-			
 	always @(posedge clk)
-		if (!rd_wait || !Nrst)
-			prevpc <= pc;
+	begin
+		if (!Nrst) begin
+			pc <= 32'hFFFFFFFC;
+			qjmp <= 0;
+			bubble <= 1;
+		end else if (!stall)
+		begin
+			bubble <= rd_wait;
+			insn <= rd_data;
+			if (!rd_wait)
+				pc <= reqpc;
+		end
+	end
 endmodule