Work on SCR-related instructions

src_Core/ISA/ISA_Decls_CHERI.bsv

@@ -98,8 +98,32 @@ typedef enum {
     SCR_MTCC      = 5'd28,
     SCR_MTDC      = 5'd29,
     SCR_MScratchC = 5'd30,
-    SCR_MEPCC     = 5'd31
-} SCR deriving(Bits, Eq, FShow);
+    SCR_MEPCC     = 5'd31,
+
+    // As with CSRs, SCR that catches all unimplemented SCRs
+    SCR_None      = 5'd10
+} SCR deriving(Bits, Eq, FShow, Bounded);
+
+function SCR unpackSCR(Bit#(5) x);
+    return (case(x)
+        pack(SCR'(SCR_PCC      )): (SCR_PCC      );
+        pack(SCR'(SCR_DDC      )): (SCR_DDC      );
+//      pack(SCR'(SCR_UTCC     )): (SCR_UTCC     );
+//      pack(SCR'(SCR_UTDC     )): (SCR_UTDC     );
+//      pack(SCR'(SCR_UScratchC)): (SCR_UScratchC);
+//      pack(SCR'(SCR_UEPCC    )): (SCR_UEPCC    );
+        pack(SCR'(SCR_STCC     )): (SCR_STCC     );
+        pack(SCR'(SCR_STDC     )): (SCR_STDC     );
+        pack(SCR'(SCR_SScratchC)): (SCR_SScratchC);
+        pack(SCR'(SCR_SEPCC    )): (SCR_SEPCC    );
+        pack(SCR'(SCR_MTCC     )): (SCR_MTCC     );
+        pack(SCR'(SCR_MTDC     )): (SCR_MTDC     );
+        pack(SCR'(SCR_MScratchC)): (SCR_MScratchC);
+        pack(SCR'(SCR_MEPCC    )): (SCR_MEPCC    );
+
+        default                  : (SCR_None     );
+    endcase);
+endfunction
 
 function CapPipe update_scr_via_csr (CapPipe old_scr, WordXL new_csr);
     let new_scr = setOffset(old_scr, new_csr);

src_Core/RISCY_OOO/procs/RV64G_OOO/AluExePipeline.bsv

@@ -256,6 +256,9 @@ module mkAluExePipeline#(AluExeInput inIfc)(AluExePipeline);
 
         // get rVal2 (check bypass)
         CapPipe rVal2 = nullCap;
+        if(x.dInst.scr matches tagged Valid .scr) begin
+            rVal2 = cast(inIfc.scaprf_rd(scr));
+        end
         if(x.regs.src2 matches tagged Valid .src2 &&& src2 != 0) begin
             rVal2 <- readRFBypass(src2, regsReady.src2, inIfc.rf_rd2(src2), bypassWire);
         end

src_Core/RISCY_OOO/procs/lib/Decode.bsv

@@ -753,7 +753,21 @@ function DecodeResult decode(Instruction inst);
                 f3_cap_ThreeOp: begin
                     case (funct7)
                         f7_cap_CSpecialRW: begin
-                            // TODO
+                            // TODO capChecks
+
+                            dInst.iType = Alu;
+                            regs.dst = Valid(tagged Gpr rd);
+                            regs.src1 = Valid(tagged Gpr rs1);
+                            regs.src2 = Invalid;
+                            dInst.scr = Valid (unpackSCR(rs2));
+
+                            let scrType = case (rs2[1:0])
+                                              0: TCC;
+                                              3: EPCC;
+                                              default: Normal;
+                                          endcase;
+
+                            dInst.execFunc = CapModify (SpecialRW (scrType));
                         end
                         f7_cap_CSetBounds: begin
                             illegalInst = True;
@@ -922,7 +936,13 @@ function DecodeResult decode(Instruction inst);
                             dInst.iType = Alu;
                             regs.dst = Valid(tagged Gpr rd);
                             regs.src1 = Valid(tagged Gpr rs1);
-                            regs.src2 = Valid(tagged Gpr rs2);
+                            if (rs2 == 0) begin
+                                regs.src2 = Invalid;
+                                dInst.scr = Valid (SCR_DDC);
+                            end else begin
+                                regs.src2 = Valid (tagged Gpr rs2);
+                                dInst.scr = Invalid;
+                            end
                             dInst.imm = Invalid;
                             dInst.execFunc = CapInspect (ToPtr);
                         end

src_Core/RISCY_OOO/procs/lib/Exec.bsv

@@ -116,8 +116,8 @@ function CapPipe capModify(CapPipe a, CapPipe b, CapModifyFunc func);
                 modifyOffset(a, getAddr(b), offsetOp == IncOffset).value;
             tagged SetBounds .boundsOp    :
                 setBoundsALU(a, getAddr(b), boundsOp);
-            //tagged SpecialRW              :
-            //    error("SpecialRW not yet implemented");
+            tagged SpecialRW .scrType     :
+                a; //TODO masking of various bits
             tagged SetAddr .addrSource    :
                 setAddr(a, addrSource == Src2Type ? (isSealed(b) ? zeroExtend(getType(b)) : -1) : getAddr(b)).value;
             tagged Seal                   :
@@ -277,7 +277,7 @@ function ExecResult basicExec(DecodedInst dInst, CapPipe rVal1, CapPipe rVal2, C
             Ld, St, Lr, Sc, Amo : nullWithAddr(alu_result);
             default             : nullWithAddr(cf.nextPc);
         endcase);
-    CapPipe scr_data = rVal1;
+    CapPipe scr_data = modify_result;
 
     return ExecResult{data: data, csrData: csr_data, scrData: scr_data, addr: addr, controlFlow: cf, capException: capException};
 endfunction

src_Core/RISCY_OOO/procs/lib/ProcTypes.bsv

@@ -423,6 +423,10 @@ typedef enum {
     SetBounds, CRRL, CRAM
 } SetBoundsFunc deriving(Bits, Eq, FShow);
 
+typedef enum {
+    TCC, EPCC, Normal
+} SpecialRWFunc deriving(Bits, Eq, FShow);
+
 typedef enum {
     Src2Type, Src2Addr
 } AddrSource deriving(Bits, Eq, FShow);
@@ -434,7 +438,7 @@ typedef enum {
 typedef union tagged {
     ModifyOffsetFunc ModifyOffset;
     SetBoundsFunc SetBounds;
-    void SpecialRW;
+    SpecialRWFunc SpecialRW;
     AddrSource SetAddr;
     void Seal;
     SrcSelector Unseal;