Moved delegation logic from privmode to trap to simplify interface

pipelined/src/privileged/privileged.sv

@@ -99,13 +99,14 @@ module privileged (
   logic       STATUS_MIE, STATUS_SIE;
   logic [11:0] MIP_REGW, MIE_REGW;
   logic [1:0] NextPrivilegeModeM;
+  logic       DelegateM;
 
   ///////////////////////////////////////////
   // track the current privilege level
   ///////////////////////////////////////////
 
-  privmode privmode(.clk, .reset, .StallW, .TrapM, .mretM, .sretM, .InterruptM, .CauseM, 
-                    .MEDELEG_REGW, .MIDELEG_REGW, .STATUS_MPP, .STATUS_SPP, .NextPrivilegeModeM, .PrivilegeModeW);
+  privmode privmode(.clk, .reset, .StallW, .TrapM, .mretM, .sretM, .DelegateM,
+                    .STATUS_MPP, .STATUS_SPP, .NextPrivilegeModeM, .PrivilegeModeW);
 
   ///////////////////////////////////////////
   // decode privileged instructions
@@ -158,11 +159,11 @@ module privileged (
             .LoadPageFaultM, .StoreAmoPageFaultM,
             .mretM, .sretM, 
             .PrivilegeModeW, 
-            .MIP_REGW, .MIE_REGW, .MIDELEG_REGW,
+            .MIP_REGW, .MIE_REGW, .MIDELEG_REGW, .MEDELEG_REGW,
             .STATUS_MIE, .STATUS_SIE,
             .InstrValidM, .CommittedM,  
             .TrapM, .RetM,
-            .InterruptM, .IntPendingM,
+            .InterruptM, .IntPendingM, .DelegateM,
             .CauseM);
 endmodule
 

pipelined/src/privileged/privmode.sv

@@ -33,25 +33,18 @@
 
 module privmode (
   input  logic             clk, reset,
-  input  logic             StallW, TrapM, mretM, sretM, InterruptM,
-  input  logic [`LOG_XLEN-1:0] CauseM, 
-  input  logic [`XLEN-1:0] MEDELEG_REGW,
-  input  logic [11:0]      MIDELEG_REGW,
+  input  logic             StallW, TrapM, mretM, sretM,
+  input  logic             DelegateM,
   input  logic [1:0]       STATUS_MPP,
   input  logic             STATUS_SPP,
   output logic [1:0]       NextPrivilegeModeM, PrivilegeModeW
 ); 
   
   if (`U_SUPPORTED) begin:privmode
-    logic       md;
-
-    // get bits of DELEG registers based on CAUSE
-    assign md = InterruptM ? MIDELEG_REGW[CauseM[3:0]] : MEDELEG_REGW[CauseM];
-    
     // PrivilegeMode FSM
     always_comb begin
       if (TrapM) begin // Change privilege based on DELEG registers (see 3.1.8)
-        if (`S_SUPPORTED & md & (PrivilegeModeW == `U_MODE | PrivilegeModeW == `S_MODE))
+        if (`S_SUPPORTED & DelegateM)
                           NextPrivilegeModeM = `S_MODE;
         else              NextPrivilegeModeM = `M_MODE;
       end else if (mretM) NextPrivilegeModeM = STATUS_MPP;

pipelined/src/privileged/trap.sv

@@ -39,11 +39,12 @@ module trap (
   (* mark_debug = "true" *) input logic 		   LoadPageFaultM, StoreAmoPageFaultM,
   (* mark_debug = "true" *) input logic 		   mretM, sretM, 
   input logic [1:0] 	   PrivilegeModeW, 
-  (* mark_debug = "true" *) input logic [11:0] 	   MIP_REGW, MIE_REGW, MIDELEG_REGW,
+  (* mark_debug = "true" *) input logic [11:0] 	   MIP_REGW, MIE_REGW, MIDELEG_REGW, 
+  input logic [`XLEN-1:0] MEDELEG_REGW,
   input logic 		   STATUS_MIE, STATUS_SIE,
   input logic 		   InstrValidM, CommittedM, 
   output logic 		   TrapM, RetM,
-  output logic 		   InterruptM, IntPendingM,
+  output logic 		   InterruptM, IntPendingM, DelegateM,
   output logic [`LOG_XLEN-1:0] CauseM 
 );
 
@@ -63,6 +64,8 @@ module trap (
   assign IntPendingM = |PendingIntsM;
   assign ValidIntsM = {12{MIntGlobalEnM}} & PendingIntsM & ~MIDELEG_REGW | {12{SIntGlobalEnM}} & PendingIntsM & MIDELEG_REGW; 
   assign InterruptM = (|ValidIntsM) && InstrValidM && ~(CommittedM);  // *** RT. CommittedM is a temporary hack to prevent integer division from having an interrupt during divide.
+  assign DelegateM = (InterruptM ? MIDELEG_REGW[CauseM[3:0]] : MEDELEG_REGW[CauseM]) & 
+                     (PrivilegeModeW == `U_MODE | PrivilegeModeW == `S_MODE);
 
   ///////////////////////////////////////////
   // Trigger Traps and RET