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continued simplifying integer division special cases

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This commit is contained in:
David Harris 2022-12-30 07:40:28 -08:00
parent bd16fd79d4
commit 58218dbdd1
1 changed files with 7 additions and 46 deletions
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53
pipelined/src/fpu/fdivsqrt/fdivsqrtpostproc.sv
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@ -113,9 +113,12 @@ module fdivsqrtpostproc(
// special case logic // special case logic
always_comb always_comb
if (ALTBM) begin if (BZeroM) begin
if (RemOpM) PreFPIntDivResultM = {{(`DIVb-`XLEN+4){1'b0}}, AM}; if (RemOpM) SpecialFPIntDivResultM = AM;
else PreFPIntDivResultM = '0; else SpecialFPIntDivResultM = {(`XLEN){1'b1}};
end else if (ALTBM) begin
if (RemOpM) SpecialFPIntDivResultM = AM;
else SpecialFPIntDivResultM = '0;
// IntQuotM = '0; // IntQuotM = '0;
// IntRemM = {{(`DIVb-`XLEN+4){1'b0}}, AM}; // IntRemM = {{(`DIVb-`XLEN+4){1'b0}}, AM};
end else begin end else begin
@ -143,51 +146,9 @@ module fdivsqrtpostproc(
PreResultM = IntQuotM; PreResultM = IntQuotM;
end end
PreFPIntDivResultM = $signed(PreResultM >>> NormShiftM); PreFPIntDivResultM = $signed(PreResultM >>> NormShiftM);
SpecialFPIntDivResultM = PreFPIntDivResultM[`XLEN-1:0];
end end
assign SpecialFPIntDivResultM = BZeroM ? (RemOpM ? AM : {(`XLEN){1'b1}}) : PreFPIntDivResultM[`XLEN-1:0]; // special cases
/*
// Integer division: Special cases
always_comb
if (ALTBM) begin
IntQuotM = '0;
IntRemM = {{(`DIVb-`XLEN+4){1'b0}}, AM};
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, PreQmM};
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;
end
// integer 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 ? AM : {(`XLEN){1'b1}}) : PreFPIntDivResultM[`XLEN-1:0]; // special cases
*/
// sign extend result for W64 // sign extend result for W64
if (`XLEN==64) if (`XLEN==64)
assign FPIntDivResultM = (W64M ? {{(`XLEN-32){SpecialFPIntDivResultM[31]}}, SpecialFPIntDivResultM[31:0]} : assign FPIntDivResultM = (W64M ? {{(`XLEN-32){SpecialFPIntDivResultM[31]}}, SpecialFPIntDivResultM[31:0]} :