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reworked fmashiftcalc to match book

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This commit is contained in:
Katherine Parry 2022-07-19 00:04:24 +00:00
parent 6ec2a5db4a
commit a590728350
1 changed files with 38 additions and 31 deletions
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69
pipelined/src/fpu/fmashiftcalc.sv
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@ -43,6 +43,7 @@ module fmashiftcalc(
);
logic [$clog2(3*`NF+7)-1:0] DenormShift; // right shift if the result is denormalized //***change this later
logic [`NE+1:0] NormSumExp; // the exponent of the normalized sum with the `FLEN bias
logic [`NE+1:0] BiasCorr;
///////////////////////////////////////////////////////////////////////////////
// Normalization
@ -50,37 +51,40 @@ module fmashiftcalc(
//*** insert bias-bias simplification in fcvt.sv/phone pictures
// Determine if the sum is zero
assign FmaSZero = ~(|FmaSm);
logic [`NE+1:0] FmaSe;
assign FmaSe = FmaKillProd ? {2'b0, Ze} : FmaPe;
// calculate the sum's exponent
// ProdExp - NormCnt - 1 + NF+4 = ProdExp + ~NormCnt + 1 - 1 + NF+4 = ProdExp + ~NormCnt + NF+4
assign NormSumExp = (FmaKillProd ? {2'b0, Ze} : FmaPe) + {{`NE+2-$unsigned($clog2(3*`NF+7)){1'b1}}, ~FmaNCnt} + (`NE+2)'(`NF+4);
assign NormSumExp = FmaSe + {{`NE+2-$unsigned($clog2(3*`NF+7)){1'b1}}, ~FmaNCnt} + (`NE+2)'(`NF+4);
//convert the sum's exponent into the proper percision
if (`FPSIZES == 1) begin
assign FmaNe = NormSumExp;
end else if (`FPSIZES == 2) begin
assign FmaNe = Fmt ? NormSumExp : (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`BIAS1))&{`NE+2{|NormSumExp}};
assign BiasCorr = Fmt ? (`NE+2)'(0) : (`NE+2)'(`BIAS1-`BIAS);
assign FmaNe = NormSumExp+BiasCorr;
end else if (`FPSIZES == 3) begin
always_comb begin
case (Fmt)
`FMT: FmaNe = NormSumExp;
`FMT1: FmaNe = (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`BIAS1))&{`NE+2{|NormSumExp}};
`FMT2: FmaNe = (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`BIAS2))&{`NE+2{|NormSumExp}};
default: FmaNe = {`NE+2{1'bx}};
`FMT: BiasCorr = '0;
`FMT1: BiasCorr = (`NE+2)'(`BIAS1-`BIAS);
`FMT2: BiasCorr = (`NE+2)'(`BIAS2-`BIAS);
default: BiasCorr = 'x;
endcase
end
assign FmaNe = NormSumExp+BiasCorr;
end else if (`FPSIZES == 4) begin
always_comb begin
case (Fmt)
2'h3: FmaNe = NormSumExp;
2'h1: FmaNe = (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`D_BIAS))&{`NE+2{|NormSumExp}};
2'h0: FmaNe = (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`S_BIAS))&{`NE+2{|NormSumExp}};
2'h2: FmaNe = (NormSumExp-(`NE+2)'(`BIAS)+(`NE+2)'(`H_BIAS))&{`NE+2{|NormSumExp}};
2'h3: BiasCorr = '0;
2'h1: BiasCorr = (`NE+2)'(`D_BIAS-`Q_BIAS);
2'h0: BiasCorr = (`NE+2)'(`S_BIAS-`Q_BIAS);
2'h2: BiasCorr = (`NE+2)'(`H_BIAS-`Q_BIAS);
endcase
end
assign FmaNe = NormSumExp+BiasCorr;
end
@ -89,25 +93,25 @@ module fmashiftcalc(
if (`FPSIZES == 1) begin
logic Sum0LEZ, Sum0GEFL;
assign Sum0LEZ = NormSumExp[`NE+1] | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF)-(`NE+2)'(2));
assign Sum0GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF-2));
assign FmaPreResultDenorm = Sum0LEZ & Sum0GEFL & ~FmaSZero;
end else if (`FPSIZES == 2) begin
logic Sum0LEZ, Sum0GEFL, Sum1LEZ, Sum1GEFL;
assign Sum0LEZ = NormSumExp[`NE+1] | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF)-(`NE+2)'(2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`BIAS1));
assign Sum1GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF1+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`BIAS1)) | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF-2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`BIAS1));
assign Sum1GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF1-2+`BIAS-`BIAS1)) | ~|NormSumExp;
assign FmaPreResultDenorm = (Fmt ? Sum0LEZ : Sum1LEZ) & (Fmt ? Sum0GEFL : Sum1GEFL) & ~FmaSZero;
end else if (`FPSIZES == 3) begin
logic Sum0LEZ, Sum0GEFL, Sum1LEZ, Sum1GEFL, Sum2LEZ, Sum2GEFL;
assign Sum0LEZ = NormSumExp[`NE+1] | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF)-(`NE+2)'(2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`BIAS1));
assign Sum1GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF1+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`BIAS1)) | ~|NormSumExp;
assign Sum2LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`BIAS2));
assign Sum2GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF2+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`BIAS2)) | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF-2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`BIAS1));
assign Sum1GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF1-2+`BIAS-`BIAS1)) | ~|NormSumExp;
assign Sum2LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`BIAS2));
assign Sum2GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF2-2+`BIAS-`BIAS2)) | ~|NormSumExp;
always_comb begin
case (Fmt)
`FMT: FmaPreResultDenorm = Sum0LEZ & Sum0GEFL & ~FmaSZero;
@ -120,20 +124,20 @@ module fmashiftcalc(
end else if (`FPSIZES == 4) begin
logic Sum0LEZ, Sum0GEFL, Sum1LEZ, Sum1GEFL, Sum2LEZ, Sum2GEFL, Sum3LEZ, Sum3GEFL;
assign Sum0LEZ = NormSumExp[`NE+1] | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`NF )-(`NE+2)'(2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`D_BIAS));
assign Sum1GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`D_NF+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`D_BIAS)) | ~|NormSumExp;
assign Sum2LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`S_BIAS));
assign Sum2GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`S_NF+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`S_BIAS)) | ~|NormSumExp;
assign Sum3LEZ = $signed(NormSumExp) <= $signed( (`NE+2)'(`BIAS)-(`NE+2)'(`H_BIAS));
assign Sum3GEFL = $signed(NormSumExp) >= $signed(-(`NE+2)'(`H_NF+2)+(`NE+2)'(`BIAS)-(`NE+2)'(`H_BIAS)) | ~|NormSumExp;
assign Sum0GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`NF-2));
assign Sum1LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`D_BIAS));
assign Sum1GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`D_NF-2+`BIAS-`D_BIAS)) | ~|NormSumExp;
assign Sum2LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`S_BIAS));
assign Sum2GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`S_NF-2+`BIAS-`S_BIAS)) | ~|NormSumExp;
assign Sum3LEZ = $signed(NormSumExp) <= $signed((`NE+2)'(`BIAS-`H_BIAS));
assign Sum3GEFL = $signed(NormSumExp) >= $signed((`NE+2)'(-`H_NF-2+`BIAS-`H_BIAS)) | ~|NormSumExp;
always_comb begin
case (Fmt)
2'h3: FmaPreResultDenorm = Sum0LEZ & Sum0GEFL & ~FmaSZero;
2'h1: FmaPreResultDenorm = Sum1LEZ & Sum1GEFL & ~FmaSZero;
2'h0: FmaPreResultDenorm = Sum2LEZ & Sum2GEFL & ~FmaSZero;
2'h2: FmaPreResultDenorm = Sum3LEZ & Sum3GEFL & ~FmaSZero;
endcase // *** remove checking to see if it's underflowed and only check for less than zero for denorm checking
endcase
end
end
@ -152,5 +156,8 @@ module fmashiftcalc(
// set and calculate the shift input and amount
// - shift once if killing a product and the result is denormalized
assign FmaShiftIn = {3'b0, FmaSm};
assign FmaShiftAmt = FmaNCnt+DenormShift;
if (`FPSIZES == 1)
assign FmaShiftAmt = FmaPreResultDenorm ? FmaSe[$clog2(3*`NF+7)-1:0]+($clog2(3*`NF+7))'(`NF+3): FmaNCnt+1;
else
assign FmaShiftAmt = FmaPreResultDenorm ? FmaSe[$clog2(3*`NF+7)-1:0]+($clog2(3*`NF+7))'(`NF+3)+BiasCorr[$clog2(3*`NF+7)-1:0]: FmaNCnt+1;
endmodule