Execute: Add delayed flush logic.

[firearm.git] / Execute.v

diff --git a/Execute.v b/Execute.v
index 7f4cf6c988df5ac3c647bd12c6509c67b004f62c..66a63e5a3575124c4c1b887e57e8ae8bd07b5f37 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;
@@ -101,7 +108,7 @@ module Execute(
                alu_setflags = 1'bx;
 
                jmp = 1'b0;
-               jmppc = 32'hxxxxxxxx;
+               jmppc = 32'h00000000;
 
                casez (insn)
                `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
@@ -171,12 +178,12 @@ module Execute(
                begin end
                `DECODE_BRANCH:
                begin
-                       if(!inbubble) begin
+                       if(!inbubble && !flush && !delayedflush) begin
                                jmppc = pc + op0 + 32'h8;
                                if(insn[24]) begin
                                        next_write_reg = 1;
                                        next_write_num = 4'hE; /* link register */
-                                       next_write_data = pc - 32'h4;
+                                       next_write_data = pc + 32'h4;
                                end
                                jmp = 1'b1;
                        end