Added negative-result int diviison support in U and UM registers. 13 tests pass!

pipelined/config/shared/wally-shared.vh

@@ -120,7 +120,7 @@
 `define LOGR ((`RADIX==2) ? 32'h1 : 32'h2)
 `define RK (`DIVCOPIES*`LOGR) // r*k used for intdiv preproc
 `define LOGK ($clog2(`DIVCOPIES))
-`define LOGRK ($clog2(`RADIX*`DIVCOPIES)) // log2(R*k)
+`define LOGRK ($clog2(`RK)) // log2(r*k)
 // FPDUR = ceil(DIVRESLEN/(LOGR*DIVCOPIES)) 
 // one iteration is required for the integer bit for minimally redundent radix-4
 `define FPDUR ((`DIVN+1+(`LOGR*`DIVCOPIES))/(`LOGR*`DIVCOPIES)+(`RADIX/4))

pipelined/src/fpu/fdivsqrt/fdivsqrt.sv

@@ -67,14 +67,14 @@ module fdivsqrt(
   logic WZeroM, AZeroM, BZeroM, AZeroE, BZeroE;
   logic SpecialCaseM;
   logic [`DIVBLEN:0] nE, nM, mM;
-  logic OTFCSwapE, ALTBM, As;
+  logic CalcOTFCSwapE, OTFCSwapE, ALTBM, As;
   logic DivStartE;
   logic [`XLEN-1:0] ForwardedSrcAM;
 
   fdivsqrtpreproc fdivsqrtpreproc(
     .clk, .IFDivStartE, .Xm(XmE), .QeM, .Xe(XeE), .Fmt(FmtE), .Ye(YeE), 
     .Sqrt(SqrtE), .Ym(YmE), .XZeroE, .X, .DPreproc, .ForwardedSrcAM,
-    .nE, .nM, .mM, .OTFCSwapE, .ALTBM, .AZeroM, .BZeroM, .AZeroE, .BZeroE, .As,
+    .nE, .nM, .mM, .CalcOTFCSwapE, .OTFCSwapE, .ALTBM, .AZeroM, .BZeroM, .AZeroE, .BZeroE, .As,
     .ForwardedSrcAE, .ForwardedSrcBE, .Funct3E, .Funct3M, .MDUE, .W64E);
   fdivsqrtfsm fdivsqrtfsm(
     .clk, .reset, .FmtE, .XsE, .SqrtE, .nE,
@@ -85,11 +85,11 @@ module fdivsqrt(
   fdivsqrtiter fdivsqrtiter(
     .clk, .Firstun, .D, .FirstU, .FirstUM, .FirstC, .MDUE, .SqrtE, // .SqrtM,
     .X,.DPreproc, .FirstWS(WS), .FirstWC(WC),
-    .IFDivStartE, .Xe(XeE), .Ye(YeE), .XZeroE, .YZeroE, .OTFCSwapE,
+    .IFDivStartE, .Xe(XeE), .Ye(YeE), .XZeroE, .YZeroE, .CalcOTFCSwapE, .OTFCSwapE,
     .FDivBusyE);
   fdivsqrtpostproc fdivsqrtpostproc(
     .WS, .WC, .D, .FirstU, .FirstUM, .FirstC, .Firstun, 
     .SqrtM, .SpecialCaseM, .RemOpM(Funct3M[1]), .ForwardedSrcAM,
-    .nM, .ALTBM, .mM, .BZeroM, .As,
+    .nM, .ALTBM, .mM, .BZeroM, .As, .OTFCSwapEM(OTFCSwapE),
     .QmM, .WZeroM, .DivSM, .FPIntDivResultM);
 endmodule

pipelined/src/fpu/fdivsqrt/fdivsqrtiter.sv

@@ -38,7 +38,7 @@ module fdivsqrtiter(
   input  logic XZeroE, YZeroE, 
   input  logic SqrtE, MDUE,
 //  input  logic SqrtM,
-  input  logic OTFCSwapE,
+  input  logic CalcOTFCSwapE, OTFCSwapE,
   input  logic [`DIVb+3:0] X,
   input  logic [`DIVb-1:0] DPreproc,
   output logic [`DIVb-1:0] D,
@@ -81,9 +81,9 @@ module fdivsqrtiter(
   flopen #(`DIVb+4) wcreg(clk, FDivBusyE, WCN, WC[0]);
 
   // UOTFC Result U and UM registers/initialization mux
-  // Initialize U to 1.0 and UM to 0 for square root; U to 0 and UM to -1 for division
+  // Initialize U to 1.0 and UM to 0 for square root or negative-result int division; U to 0 and UM to -1 otherwise
-  assign initU = (SqrtE & ~(MDUE)) ? {1'b1, {(`DIVb){1'b0}}} : 0;
+  assign initU =  ((MDUE & CalcOTFCSwapE) | (SqrtE & ~(MDUE))) ? {1'b1, {(`DIVb){1'b0}}} : 0;
-  assign initUM = (SqrtE & ~(MDUE)) ? 0 : {1'b1, {(`DIVb){1'b0}}}; 
+  assign initUM = ((MDUE & CalcOTFCSwapE) | (SqrtE & ~(MDUE))) ? 0 : {1'b1, {(`DIVb){1'b0}}}; 
   mux2   #(`DIVb+1) Umux(UNext[`DIVCOPIES-1], initU, IFDivStartE, UMux);
   mux2   #(`DIVb+1) UMmux(UMNext[`DIVCOPIES-1], initUM, IFDivStartE, UMMux);
   flopen #(`DIVb+1) UReg(clk, IFDivStartE|FDivBusyE, UMux, U[0]);

pipelined/src/fpu/fdivsqrt/fdivsqrtpostproc.sv

@@ -35,9 +35,7 @@ module fdivsqrtpostproc(
   input  logic [`DIVb-1:0]  D, 
   input  logic [`DIVb:0]    FirstU, FirstUM, 
   input  logic [`DIVb+1:0]  FirstC,
-  input  logic              Firstun,
+  input  logic              Firstun, SqrtM, SpecialCaseM, OTFCSwapEM,
-  input  logic              SqrtM,
-  input  logic              SpecialCaseM,
 	input  logic [`XLEN-1:0]  ForwardedSrcAM,
   input  logic              RemOpM, ALTBM, BZeroM, As,
   input  logic [`DIVBLEN:0] nM, mM,
@@ -54,7 +52,7 @@ module fdivsqrtpostproc(
   logic [`DIVBLEN:0] NormShiftM;
   logic [`DIVb:0] IntQuotM, NormQuotM;
   logic [`DIVb+3:0] IntRemM, NormRemM;
-  logic [`DIVb+3:0] PreResultM, PreFPIntDivResultM;
+  logic signed [`DIVb+3:0] PreResultM, PreFPIntDivResultM;
 
   // check for early termination on an exact result.  If the result is not exact, the sticky should be set
   aplusbeq0 #(`DIVb+4) wspluswceq0(WS, WC, weq0);
@@ -130,11 +128,10 @@ module fdivsqrtpostproc(
       NormShiftM = (mM + (`DIVBLEN+1)'(`DIVa));
       PreResultM = IntRemM;
     end else begin
-      if (BZeroM) begin
+      NormShiftM = ((`DIVBLEN+1)'(`DIVb) - (nM * (`DIVBLEN+1)'(`LOGR)));
-        NormShiftM = 0;
+      if (BZeroM | (~ALTBM & OTFCSwapEM)) begin
         PreResultM = {3'b111, IntQuotM};
       end else begin
-        NormShiftM = ((`DIVBLEN+1)'(`DIVb) - (nM * (`DIVBLEN+1)'(`LOGR)));
         PreResultM = {3'b000, IntQuotM};
       end
       //PreResultM = {IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM}; // Suspicious Sign Extender
@@ -143,7 +140,7 @@ module fdivsqrtpostproc(
 
    // division takes the result from the next cycle, which is shifted to the left one more time so the square root also needs to be shifted
   
-  assign PreFPIntDivResultM = ($signed(PreResultM) >>> NormShiftM) + {{(`DIVb+3){1'b0}}, (PostIncM & ~RemOpM)};
+  assign PreFPIntDivResultM = $signed(PreResultM >>> NormShiftM) + {{(`DIVb+3){1'b0}}, (PostIncM & ~RemOpM)};
   assign FPIntDivResultM = PreFPIntDivResultM[`XLEN-1:0];
  
   assign PreQmM = NegStickyM ? FirstUM : FirstU; // Select U or U-1 depending on negative sticky bit

pipelined/src/fpu/fdivsqrt/fdivsqrtpreproc.sv

@@ -42,7 +42,7 @@ module fdivsqrtpreproc (
 	input  logic [2:0] 	Funct3E, Funct3M,
 	input  logic MDUE, W64E,
   output logic [`DIVBLEN:0] nE, nM, mM,
-  output logic OTFCSwapE, ALTBM, As, AZeroM, BZeroM, AZeroE, BZeroE,
+  output logic CalcOTFCSwapE, OTFCSwapE, ALTBM, As, AZeroM, BZeroM, AZeroE, BZeroE,
   output logic [`NE+1:0] QeM,
   output logic [`DIVb+3:0] X,
   output logic [`DIVb-1:0] DPreproc,
@@ -56,7 +56,7 @@ module fdivsqrtpreproc (
   // Intdiv signals
   logic  [`DIVb-1:0] IFNormLenX, IFNormLenD;
   logic  [`XLEN-1:0] PosA, PosB;
-  logic  Bs, CalcOTFCSwapE, ALTBE;
+  logic  Bs, ALTBE;
   logic  [`XLEN-1:0]  A64, B64;
   logic  [`DIVBLEN:0] mE;
   logic  [`DIVBLEN:0] ZeroDiff, IntBits, RightShiftX;