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Moved IDIV for postproc into generate block

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David Harris 2022-12-27 22:02:14 -08:00
parent d59878a886
commit a832605658
1 changed files with 73 additions and 72 deletions
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145
pipelined/src/fpu/fdivsqrt/fdivsqrtpostproc.sv
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@ -98,79 +98,80 @@ module fdivsqrtpostproc(
// Determine if sticky bit is negative // *** look for ways to optimize this. Shift shouldn't be needed.
assign Sum = WC + WS;
assign W = $signed(Sum) >>> `LOGR;
assign NegStickyM = W[`DIVb+3];
assign DM = {4'b0001, D};
// *** put conditionals on integer division hardware, move to its own module
// Integer division: sign handling for div and rem
always_comb
if (~AsM)
if (NegStickyM) begin
NormQuotM = FirstUM;
NormRemM = W + DM;
end else begin
NormQuotM = FirstU;
NormRemM = W;
end
else
if (NegStickyM) begin
NormQuotM = FirstUM;
NormRemM = -(W + DM);
end else begin
NormQuotM = FirstU;
NormRemM = -W;
end
// Integer division: Special cases
always_comb
if (ALTBM) begin
IntQuotM = '0;
IntRemM = {{(`DIVb-`XLEN+4){1'b0}}, ForwardedSrcAM};
end else begin
logic [`DIVb+3:0] PreIntQuotM;
if (WZeroM) begin
if (weq0M) begin
PreIntQuotM = {3'b000, FirstU};
IntRemM = '0;
end else begin
PreIntQuotM = {3'b000, FirstUM};
IntRemM = '0;
end
end else begin
PreIntQuotM = {3'b000, NormQuotM};
IntRemM = NormRemM;
end
// flip sign if necessary
if (NegQuotM) IntQuotM = -PreIntQuotM;
else IntQuotM = PreIntQuotM;
end
assign NegStickyM = Sum[`DIVb+3];
always_comb
if (RemOpM) begin
NormShiftM = ALTBM ? '0 : (mM + (`DIVBLEN+1)'(`DIVa)); // no postshift if forwarding input A to remainder
PreResultM = IntRemM;
end else begin
NormShiftM = ((`DIVBLEN+1)'(`DIVb) - (nM * (`DIVBLEN+1)'(`LOGR)));
PreResultM = IntQuotM;
/*
if (~ALTBM & NegQuotM) begin
PreResultM = {3'b111, -IntQuotM};
end else begin
PreResultM = {3'b000, IntQuotM};
end*/
//PreResultM = {IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM}; // Suspicious Sign Extender
end
// 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);
assign SpecialFPIntDivResultM = BZeroM ? (RemOpM ? ForwardedSrcAM : {(`XLEN){1'b1}}) : PreFPIntDivResultM[`XLEN-1:0]; // special cases
// *** conditional on RV64
assign FPIntDivResultM = (W64M ? {{(`XLEN-32){SpecialFPIntDivResultM[31]}}, SpecialFPIntDivResultM[31:0]} : SpecialFPIntDivResultM[`XLEN-1:0]); // Sign extending in case of W64
assign PreQmM = NegStickyM ? FirstUM : FirstU; // Select U or U-1 depending on negative sticky bit
assign QmM = SqrtM ? (PreQmM << 1) : PreQmM;
if (`IDIV_ON_FPU) begin
assign W = $signed(Sum) >>> `LOGR;
assign DM = {4'b0001, D};
// Integer division: sign handling for div and rem
always_comb
if (~AsM)
if (NegStickyM) begin
NormQuotM = FirstUM;
NormRemM = W + DM;
end else begin
NormQuotM = FirstU;
NormRemM = W;
end
else
if (NegStickyM) begin
NormQuotM = FirstUM;
NormRemM = -(W + DM);
end else begin
NormQuotM = FirstU;
NormRemM = -W;
end
// Integer division: Special cases
always_comb
if (ALTBM) begin
IntQuotM = '0;
IntRemM = {{(`DIVb-`XLEN+4){1'b0}}, ForwardedSrcAM};
end else begin
logic [`DIVb+3:0] PreIntQuotM;
if (WZeroM) begin
if (weq0M) begin
PreIntQuotM = {3'b000, FirstU};
IntRemM = '0;
end else begin
PreIntQuotM = {3'b000, FirstUM};
IntRemM = '0;
end
end else begin
PreIntQuotM = {3'b000, NormQuotM};
IntRemM = NormRemM;
end
// flip sign if necessary
if (NegQuotM) IntQuotM = -PreIntQuotM;
else IntQuotM = PreIntQuotM;
end
always_comb
if (RemOpM) begin
NormShiftM = ALTBM ? '0 : (mM + (`DIVBLEN+1)'(`DIVa)); // no postshift if forwarding input A to remainder
PreResultM = IntRemM;
end else begin
NormShiftM = ((`DIVBLEN+1)'(`DIVb) - (nM * (`DIVBLEN+1)'(`LOGR)));
PreResultM = IntQuotM;
/*
if (~ALTBM & NegQuotM) begin
PreResultM = {3'b111, -IntQuotM};
end else begin
PreResultM = {3'b000, IntQuotM};
end*/
//PreResultM = {IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM[`DIVb], IntQuotM}; // Suspicious Sign Extender
end
// 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);
assign SpecialFPIntDivResultM = BZeroM ? (RemOpM ? ForwardedSrcAM : {(`XLEN){1'b1}}) : PreFPIntDivResultM[`XLEN-1:0]; // special cases
// *** conditional on RV64
assign FPIntDivResultM = (W64M ? {{(`XLEN-32){SpecialFPIntDivResultM[31]}}, SpecialFPIntDivResultM[31:0]} : SpecialFPIntDivResultM[`XLEN-1:0]); // Sign extending in case of W64
end
endmodule