From 5733ed9ac0fa84e021a4604815bf55d6b25d9332 Mon Sep 17 00:00:00 2001
From: Karlis Susters <ks980@cam.ac.uk>
Date: Wed, 12 Apr 2023 21:58:35 +0300
Subject: [PATCH] Implemented overflow bypass fifo, required for double target
 table

---
 src_Core/RISCY_OOO/procs/lib/Fifos.bsv | 50 +++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/src_Core/RISCY_OOO/procs/lib/Fifos.bsv b/src_Core/RISCY_OOO/procs/lib/Fifos.bsv
index 9ad7714..813592f 100644
--- a/src_Core/RISCY_OOO/procs/lib/Fifos.bsv
+++ b/src_Core/RISCY_OOO/procs/lib/Fifos.bsv
@@ -740,4 +740,52 @@ module mkOverflowPipelineFifo( Fifo#(n, t) ) provisos (Bits#(t,tSz));
     empty[2] <= True;
     full[2] <= False;
   endmethod
-endmodule
\ No newline at end of file
+endmodule
+ 
+module mkOverflowBypassFifo( Fifo#(n, t) ) provisos (Bits#(t,tSz));
+  // n is size of fifo
+  // t is data type of fifo
+  Vector#(n, Ehr#(2,t))   data  <- replicateM(mkEhr(?));
+  Ehr#(2, Bit#(TLog#(n))) enqP  <- mkEhr(0);
+  Ehr#(3, Bit#(TLog#(n))) deqP  <- mkEhr(0);
+  Ehr#(3, Bool)           empty <- mkEhr(True);
+  Ehr#(3, Bool)           full  <- mkEhr(False);
+  Bit#(TLog#(n))          max_index = fromInteger(valueOf(n)-1);
+
+  method Bool notFull = !full[0];
+
+  method Action enq(t x);
+    data[enqP[0]][0] <= x;
+    empty[0] <= False;
+    let next_enqP = (enqP[0] == max_index) ? 0 : enqP[0] + 1;
+    if (full[0]) begin
+      deqP[0] <= next_enqP;
+    end
+    enqP[0] <= next_enqP;
+    if( next_enqP == deqP[0] ) begin
+      full[0] <= True;
+    end
+  endmethod
+
+  method Bool notEmpty = !empty[1];
+
+  method Action deq if( !empty[1] );
+    full[1] <= False;
+    let next_deqP = (deqP[1] == max_index) ? 0 : deqP[1] + 1;
+    deqP[1] <= next_deqP;
+    if( next_deqP == enqP[1] ) begin
+      empty[1] <= True;
+    end
+  endmethod
+
+  method t first if( !empty[1] );
+    return data[deqP[1]][1];
+  endmethod
+
+  method Action clear;
+    enqP[1] <= 0;
+    deqP[2] <= 0;
+    empty[2] <= True;
+    full[2] <= False;
+  endmethod
+endmodule