Register decode output in a new porch stage

2 files changed, 56 insertions, 3 deletions

diff --git a/rtl/core/decode/conds.sv b/rtl/core/porch/conds.sv
index 60922a0..b8db1e7 100644
--- a/rtl/core/decode/conds.sv
+++ b/rtl/core/porch/conds.sv
@@ -1,9 +1,9 @@
 `include "core/decode/isa.sv"
 `include "core/uarch.sv"
 
-module core_decode_conds
+module core_porch_conds
 (
-	input  logic[3:0] cond,
+	input  word       insn,
 	input  psr_flags  flags,
 
 	output logic      execute,
@@ -15,7 +15,7 @@ module core_decode_conds
 		undefined = 0;
 		conditional = 1;
 
-		unique case(cond)
+		unique case(insn `FIELD_COND)
 			`COND_EQ: execute =  flags.z;
 			`COND_NE: execute = ~flags.z;
 			`COND_HS: execute =  flags.c;
diff --git a/rtl/core/porch/porch.sv b/rtl/core/porch/porch.sv
new file mode 100644
index 0000000..6f5caf7
--- /dev/null
+++ b/rtl/core/porch/porch.sv
@@ -0,0 +1,53 @@
+`include "core/uarch.sv"
+
+module core_porch
+(
+	input  logic       clk,
+	                   flush,
+	                   stall,
+	input  psr_flags   flags,
+
+	input  word        fetch_insn,
+	input  ptr         fetch_insn_pc,
+	input  insn_decode fetch_dec,
+
+	output word        insn,
+	output ptr         insn_pc,
+	output insn_decode dec
+);
+
+	logic execute, conditional, undefined;
+	insn_decode nop, hold_dec;
+
+	core_porch_conds conds
+	(
+		.*
+	);
+
+	assign nop.ctrl.execute = 0;
+	assign nop.ctrl.undefined = 0;
+	assign nop.ctrl.conditional = 0;
+
+	always_comb begin
+		dec = hold_dec;
+		dec.ctrl.execute = !flush && dec.ctrl.execute && execute;
+		dec.ctrl.undefined = !flush && (dec.ctrl.undefined || undefined);
+		dec.ctrl.conditional = !flush && (dec.ctrl.conditional || conditional);
+	end
+
+	always @(posedge clk)
+		if(!stall) begin
+			insn <= fetch_insn;
+			hold_dec <= fetch_dec;
+
+			if(!flush)
+				insn_pc <= fetch_insn_pc;
+		end
+
+	initial begin
+		insn = `NOP;
+		insn_pc = 0;
+		hold_dec = nop;
+	end
+
+endmodule