Fetch: Rewrite for the 317235784th time, this time based off a block diagram on paper...
authorJoshua Wise <joshua@nyus.joshuawise.com>
Tue, 17 Mar 2009 01:19:51 +0000 (21:19 -0400)
committerJoshua Wise <joshua@nyus.joshuawise.com>
Tue, 17 Mar 2009 01:19:51 +0000 (21:19 -0400)
Fetch.v

diff --git a/Fetch.v b/Fetch.v
index aa9bd7c..3f28453 100644 (file)
--- a/Fetch.v
+++ b/Fetch.v
@@ -25,30 +25,30 @@ module Fetch(
                        {qjmp,qjmppc} <= {1'b0, 32'hxxxxxxxx};
        
        reg [31:0] reqpc;
-       always @(*)
-               if (stall)
-                       reqpc = pc;
-               else if (qjmp)
-                       reqpc = qjmppc;
-               else if (jmp)
-                       reqpc = jmppc;
-               else
-                       reqpc = pc + 4;
        
+       /* Output latch logic */
        assign rd_addr = reqpc;
        assign rd_req = 1;
-       
        always @(posedge clk or negedge Nrst)
-       begin
                if (!Nrst) begin
-                       pc <= 32'hFFFFFFFC;
                        bubble <= 1;
-               end else if (!stall)
-               begin
-                       bubble <= rd_wait;
+                       insn <= 0;
+                       pc <= 32'h00000000;
+               end else if (!stall) begin
+                       bubble <= (jmp || qjmp || rd_wait);
                        insn <= rd_data;
-                       if (!rd_wait)
-                               pc <= reqpc;
+                       pc <= reqpc;
+               end
+       
+       always @(posedge clk or negedge Nrst)
+               if (!Nrst)
+                       reqpc <= 0;
+               else if (!stall && !rd_wait) begin
+                       if (qjmp)
+                               reqpc <= qjmppc;
+                       else if (jmp)
+                               reqpc <= jmppc;
+                       else
+                               reqpc <= reqpc + 4;
                end
-       end
 endmodule
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