Execute: Add delayed flush logic.
authorJoshua Wise <joshua@rebirth.joshuawise.com>
Wed, 14 Jan 2009 07:18:35 +0000 (02:18 -0500)
committerJoshua Wise <joshua@rebirth.joshuawise.com>
Wed, 14 Jan 2009 07:18:35 +0000 (02:18 -0500)
Execute.v

index ab204a0..66a63e5 100644 (file)
--- a/Execute.v
+++ b/Execute.v
@@ -57,7 +57,7 @@ module Execute(
                .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op),
                .setflags(alu_setflags), .shifter_carry(carry),
                .result(alu_result), .cpsr_out(alu_outcpsr), .setres(alu_setres));
-       
+
        always @(posedge clk)
        begin
                if (!stall)
@@ -75,6 +75,13 @@ module Execute(
                        outop2 <= op2;
                end
        end
+       
+       reg delayedflush = 0;
+       always @(posedge clk)
+               if (flush && outstall /* halp! I can't do it now, maybe later? */)
+                       delayedflush <= 1;
+               else if (!outstall /* anything has been handled this time around */)
+                       delayedflush <= 0;
 
        reg prevstall = 0;
        always @(posedge clk)
@@ -83,7 +90,7 @@ module Execute(
        always @(*)
        begin
                outstall = stall;
-               next_outbubble = inbubble | flush;
+               next_outbubble = inbubble | flush | delayedflush;
                next_outcpsr = cpsr;
                next_outspsr = spsr;
                next_write_reg = 0;
@@ -171,7 +178,7 @@ module Execute(
                begin end
                `DECODE_BRANCH:
                begin
-                       if(!inbubble && !flush) begin
+                       if(!inbubble && !flush && !delayedflush) begin
                                jmppc = pc + op0 + 32'h8;
                                if(insn[24]) begin
                                        next_write_reg = 1;
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