1 files changed, 43 insertions, 0 deletions
diff --git a/rtl/core/control/stall.sv b/rtl/core/control/stall.sv
new file mode 100644
index 0000000..c2f6a4d
--- /dev/null
+++ b/rtl/core/control/stall.sv
@@ -0,0 +1,43 @@
+`include "core/uarch.sv"
+
+module core_control_stall
+(
+	input  logic           clk,
+
+	input  datapath_decode dec,
+	input  data_decode     dec_data,
+	input  snd_decode      dec_snd,
+
+	input  ctrl_cycle      next_cycle,
+	input  logic           final_update_flags,
+	                       update_flags,
+	                       final_writeback,
+	                       writeback,
+	input  reg_num         final_rd,
+
+	output logic           stall,
+	                       bubble,
+	                       next_bubble
+);
+
+	logic pc_writeback_hazard, flags_hazard, data_hazard, rn_hazard,
+	      snd_hazard, flags_dependency, updating_flags;
+
+	assign stall = next_cycle != ISSUE || next_bubble;
+	assign next_bubble = pc_writeback_hazard || flags_hazard || data_hazard;
+
+	assign pc_writeback_hazard = final_writeback && final_rd == `R15;
+	assign flags_hazard = flags_dependency && updating_flags;
+	assign data_hazard = final_writeback && (rn_hazard || snd_hazard);
+	assign rn_hazard = dec_data.uses_rn && (final_rd == dec_data.rn || dec_data.rn == `R15);
+	assign snd_hazard = !dec_snd.is_imm && (dec_snd.r == final_rd || dec_snd.r == `R15);
+
+	assign flags_dependency = dec.update_flags || dec.conditional;
+	assign updating_flags = final_update_flags || update_flags;
+
+	always_ff @(posedge clk)
+		bubble <= next_cycle == ISSUE ? next_bubble : 0;
+
+	initial bubble = 0;
+
+endmodule