init repo

1 files changed, 66 insertions, 0 deletions

diff --git a/hdl/hazard_unit.v b/hdl/hazard_unit.v
new file mode 100644
index 0000000..627c162
--- /dev/null
+++ b/hdl/hazard_unit.v
@@ -0,0 +1,66 @@
+`timescale 1ns / 1ps
+
+module hazard_unit(
+	input       clk, 
+  input       rst,
+	input [4:0] ex_dst_reg,
+	input [4:0] mem_dst_reg,
+	input [4:0] id_rs,
+	input [4:0] id_rt,
+	      
+	input [5:0] mem_opcode, 
+	input [5:0] ex_opcode, 
+	input [5:0] id_opcode,
+
+  input       id_rt_is_source,
+  input       ex_reg_write,
+  input       mem_reg_write,
+
+  output      pc_write,
+  output      if_id_write_en,
+  output reg  hazard_detected
+);
+
+   localparam 
+     LW = 6'b100011, 
+     BEQ=6'b000100;
+
+
+   assign pc_write = ~hazard_detected;
+   assign if_id_write_en = ~hazard_detected;
+
+   reg [1:0]        coincidence;
+   
+   always @*
+     begin
+        coincidence = 0;
+
+        if (ex_reg_write && ( (id_rs == ex_dst_reg) | ( (id_rt == ex_dst_reg) && id_rt_is_source)))
+          coincidence[0] = 1'b1;
+        else if (mem_reg_write && ( (id_rs == mem_dst_reg) | ( (id_rt == mem_dst_reg) && id_rt_is_source)))
+          coincidence[1] = 1'b1;        
+     end
+
+
+   always @*
+     begin
+        hazard_detected = 0;
+        
+        if (coincidence [0])
+          begin
+             if ( id_opcode == BEQ && ex_opcode == LW )
+               hazard_detected = 1;
+             else if ( id_opcode == BEQ && ex_opcode != LW)
+               hazard_detected = 1;
+             else if ( id_opcode != BEQ && ex_opcode == LW)
+               hazard_detected = 1;             
+          end
+        else if (coincidence [1])
+          begin
+             if (id_opcode == BEQ && mem_opcode == LW)
+               hazard_detected = 1;             
+          end
+     end
+     
+   
+endmodule