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FMA cleanup

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This commit is contained in:
Katherine Parry 2021-08-28 10:53:35 -04:00
parent b5d6c4fb46
commit 7607adc951
4 changed files with 234 additions and 546 deletions
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2
wally-pipelined/fpu-testfloat/FMA/tbgen/tb.sv
View File

@ -142,7 +142,7 @@ assign ansnan = FmtE ? &ans[`FLEN-2:`NF] && |ans[`NF-1:0] : &ans[30:23] && |ans[
.BiasE, .XDenormE, .YDenormE, .ZDenormE, .XZeroE, .YZeroE, .ZZeroE, .BiasE, .XDenormE, .YDenormE, .ZDenormE, .XZeroE, .YZeroE, .ZZeroE,
.FOpCtrlE, .FmtE, .SumE, .NegSumE, .InvZE, .NormCntE, .ZSgnEffE, .PSgnE, .FOpCtrlE, .FmtE, .SumE, .NegSumE, .InvZE, .NormCntE, .ZSgnEffE, .PSgnE,
.ProdExpE, .AddendStickyE, .KillProdE); .ProdExpE, .AddendStickyE, .KillProdE);
fma2 UUT2(.XSgnM(XSgnE), .YSgnM(YSgnE), .ZSgnM(ZSgnE), .XExpM(XExpE), .YExpM(YExpE), .ZExpM(ZExpE), .XManM({XAssumed1E,XFracE}), .YManM({YAssumed1E,YFracE}), .ZManM({ZAssumed1E,ZFracE}), .XNaNM(XNaNE), .YNaNM(YNaNE), .ZNaNM(ZNaNE), .XZeroM(XZeroE), .YZeroM(YZeroE), .ZZeroM(ZZeroE), .XInfM(XInfE), .YInfM(YInfE), .ZInfM(ZInfE), .XSNaNM(XSNaNE), .YSNaNM(YSNaNE), .ZSNaNM(ZSNaNE), fma2 UUT2(.XSgnM(XSgnE), .YSgnM(YSgnE), .XExpM(XExpE), .YExpM(YExpE), .ZExpM(ZExpE), .XManM({XAssumed1E,XFracE}), .YManM({YAssumed1E,YFracE}), .ZManM({ZAssumed1E,ZFracE}), .XNaNM(XNaNE), .YNaNM(YNaNE), .ZNaNM(ZNaNE), .XZeroM(XZeroE), .YZeroM(YZeroE), .ZZeroM(ZZeroE), .XInfM(XInfE), .YInfM(YInfE), .ZInfM(ZInfE), .XSNaNM(XSNaNE), .YSNaNM(YSNaNE), .ZSNaNM(ZSNaNE),
// .FSrcXE, .FSrcYE, .FSrcZE, .FSrcXM, .FSrcYM, .FSrcZM, // .FSrcXE, .FSrcYE, .FSrcZE, .FSrcXM, .FSrcYM, .FSrcZM,
.FOpCtrlM(FOpCtrlE[2:0]), .KillProdM(KillProdE), .AddendStickyM(AddendStickyE), .ProdExpM(ProdExpE), .SumM(SumE), .NegSumM(NegSumE), .InvZM(InvZE), .NormCntM(NormCntE), .ZSgnEffM(ZSgnEffE), .PSgnM(PSgnE), .FOpCtrlM(FOpCtrlE[2:0]), .KillProdM(KillProdE), .AddendStickyM(AddendStickyE), .ProdExpM(ProdExpE), .SumM(SumE), .NegSumM(NegSumE), .InvZM(InvZE), .NormCntM(NormCntE), .ZSgnEffM(ZSgnEffE), .PSgnM(PSgnE),
.FmtM(FmtE), .FrmM(FrmE), .FMAFlgM, .FMAResM); .FmtM(FmtE), .FrmM(FrmE), .FMAFlgM, .FMAResM);

654
wally-pipelined/src/fpu/fma.sv
View File

@ -31,7 +31,7 @@ module fma(
input logic FlushM, // flush the memory stage input logic FlushM, // flush the memory stage
input logic StallM, // stall memory stage input logic StallM, // stall memory stage
input logic FmtE, FmtM, // precision 1 = double 0 = single input logic FmtE, FmtM, // precision 1 = double 0 = single
input logic [2:0] FOpCtrlM, FOpCtrlE, // 000 = fmadd (X*Y)+Z, 001 = fmsub (X*Y)-Z, 010 = fnmsub -(X*Y)+Z, 011 = fnmadd -(X*Y)-Z, 100 = fmul (X*Y) input logic [2:0] FOpCtrlE, // 000 = fmadd (X*Y)+Z, 001 = fmsub (X*Y)-Z, 010 = fnmsub -(X*Y)+Z, 011 = fnmadd -(X*Y)-Z, 100 = fmul (X*Y)
input logic [2:0] FrmM, // rounding mode 000 = rount to nearest, ties to even 001 = round twords zero 010 = round down 011 = round up 100 = round to nearest, ties to max magnitude input logic [2:0] FrmM, // rounding mode 000 = rount to nearest, ties to even 001 = round twords zero 010 = round down 011 = round up 100 = round to nearest, ties to max magnitude
input logic XSgnE, YSgnE, ZSgnE, // input signs - execute stage input logic XSgnE, YSgnE, ZSgnE, // input signs - execute stage
input logic [`NE-1:0] XExpE, YExpE, ZExpE, // input exponents - execute stage input logic [`NE-1:0] XExpE, YExpE, ZExpE, // input exponents - execute stage
@ -45,21 +45,20 @@ module fma(
input logic XSNaNM, YSNaNM, ZSNaNM, // is signaling NaN input logic XSNaNM, YSNaNM, ZSNaNM, // is signaling NaN
input logic XZeroM, YZeroM, ZZeroM, // is zero - memory stage input logic XZeroM, YZeroM, ZZeroM, // is zero - memory stage
input logic XInfM, YInfM, ZInfM, // is infinity input logic XInfM, YInfM, ZInfM, // is infinity
input logic [10:0] BiasE, // bias - depends on precison (max exponent/2) input logic [10:0] BiasE, // bias (max exponent/2) ***parameterize in unpacking unit
output logic [`FLEN-1:0] FMAResM, // FMA result output logic [`FLEN-1:0] FMAResM, // FMA result
output logic [4:0] FMAFlgM); // FMA flags output logic [4:0] FMAFlgM); // FMA flags
//fma/mult //fma/mult/add
// fmadd = ?000 // fmadd = 000
// fmsub = ?001 // fmsub = 001
// fnmsub = ?010 -(a*b)+c // fnmsub = 010 -(a*b)+c
// fnmadd = ?011 -(a*b)-c // fnmadd = 011 -(a*b)-c
// fmul = ?100 // fmul = 100
// {?, is mul, negate product, negate addend} // fadd = 110
// fsub = 111
// signals transfered between pipeline stages // signals transfered between pipeline stages
// logic [2*`NF+1:0] ProdManE, ProdManM;
// logic [3*`NF+5:0] AlignedAddendE, AlignedAddendM;
logic [3*`NF+5:0] SumE, SumM; logic [3*`NF+5:0] SumE, SumM;
logic [`NE+1:0] ProdExpE, ProdExpM; logic [`NE+1:0] ProdExpE, ProdExpM;
logic AddendStickyE, AddendStickyM; logic AddendStickyE, AddendStickyM;
@ -76,7 +75,6 @@ module fma(
.ProdExpE, .AddendStickyE, .KillProdE); .ProdExpE, .AddendStickyE, .KillProdE);
// E/M pipeline registers // E/M pipeline registers
// flopenrc #(106) EMRegFma1(clk, reset, FlushM, ~StallM, ProdManE, ProdManM);
flopenrc #(3*`NF+6) EMRegFma2(clk, reset, FlushM, ~StallM, SumE, SumM); flopenrc #(3*`NF+6) EMRegFma2(clk, reset, FlushM, ~StallM, SumE, SumM);
flopenrc #(13) EMRegFma3(clk, reset, FlushM, ~StallM, ProdExpE, ProdExpM); flopenrc #(13) EMRegFma3(clk, reset, FlushM, ~StallM, ProdExpE, ProdExpM);
flopenrc #(15) EMRegFma4(clk, reset, FlushM, ~StallM, flopenrc #(15) EMRegFma4(clk, reset, FlushM, ~StallM,
@ -84,7 +82,7 @@ module fma(
{AddendStickyM, KillProdM, InvZM, NormCntM, NegSumM, ZSgnEffM, PSgnM}); {AddendStickyM, KillProdM, InvZM, NormCntM, NegSumM, ZSgnEffM, PSgnM});
fma2 fma2(.XSgnM, .YSgnM, .XExpM, .YExpM, .ZExpM, .XManM, .YManM, .ZManM, fma2 fma2(.XSgnM, .YSgnM, .XExpM, .YExpM, .ZExpM, .XManM, .YManM, .ZManM,
.FOpCtrlM, .FrmM, .FmtM, .ProdExpM, .AddendStickyM, .KillProdM, .SumM, .NegSumM, .InvZM, .NormCntM, .ZSgnEffM, .PSgnM, .FrmM, .FmtM, .ProdExpM, .AddendStickyM, .KillProdM, .SumM, .NegSumM, .InvZM, .NormCntM, .ZSgnEffM, .PSgnM,
.XZeroM, .YZeroM, .ZZeroM, .XInfM, .YInfM, .ZInfM, .XNaNM, .YNaNM, .ZNaNM, .XSNaNM, .YSNaNM, .ZSNaNM, .XZeroM, .YZeroM, .ZZeroM, .XInfM, .YInfM, .ZInfM, .XNaNM, .YNaNM, .ZNaNM, .XSNaNM, .YSNaNM, .ZSNaNM,
.FMAResM, .FMAFlgM); .FMAResM, .FMAFlgM);
@ -93,29 +91,27 @@ endmodule
module fma1( module fma1(
input logic XSgnE, YSgnE, ZSgnE, input logic XSgnE, YSgnE, ZSgnE, // input's signs
input logic [`NE-1:0] XExpE, YExpE, ZExpE, // biased exponents in B(NE.0) format input logic [`NE-1:0] XExpE, YExpE, ZExpE, // biased exponents in B(NE.0) format
input logic [`NF:0] XManE, YManE, ZManE, // fractions in U(0.NF) format] input logic [`NF:0] XManE, YManE, ZManE, // fractions in U(0.NF) format
input logic XDenormE, YDenormE, ZDenormE, // is the input denormal input logic XDenormE, YDenormE, ZDenormE, // is the input denormal
input logic XZeroE, YZeroE, ZZeroE, // is the input zero input logic XZeroE, YZeroE, ZZeroE, // is the input zero
input logic [`NE-1:0] BiasE, input logic [`NE-1:0] BiasE, // bias (max exponent/2)
input logic [2:0] FOpCtrlE, // 000 = fmadd (X*Y)+Z, 001 = fmsub (X*Y)-Z, 010 = fnmsub -(X*Y)+Z, 011 = fnmadd -(X*Y)-Z, 100 = fmul (X*Y) input logic [2:0] FOpCtrlE, // 000 = fmadd (X*Y)+Z, 001 = fmsub (X*Y)-Z, 010 = fnmsub -(X*Y)+Z, 011 = fnmadd -(X*Y)-Z, 100 = fmul (X*Y)
input logic FmtE, // precision 1 = double 0 = single input logic FmtE, // precision 1 = double 0 = single
// output logic [2*`NF+1:0] ProdManE, // 1.X frac * 1.Y frac in U(2.2Nf) format
// output logic [3*`NF+5:0] AlignedAddendE, // Z aligned for addition in U(NF+5.2NF+1)
output logic [`NE+1:0] ProdExpE, // X exponent + Y exponent - bias in B(NE+2.0) format; adds 2 bits to allow for size of number and negative sign output logic [`NE+1:0] ProdExpE, // X exponent + Y exponent - bias in B(NE+2.0) format; adds 2 bits to allow for size of number and negative sign
output logic AddendStickyE, // sticky bit that is calculated during alignment output logic AddendStickyE, // sticky bit that is calculated during alignment
output logic KillProdE, // set the product to zero before addition if the product is too small to matter output logic KillProdE, // set the product to zero before addition if the product is too small to matter
output logic [3*`NF+5:0] SumE, output logic [3*`NF+5:0] SumE, // the positive sum
output logic NegSumE, output logic NegSumE, // was the sum negitive
output logic InvZE, output logic InvZE, // intert Z
output logic ZSgnEffE, output logic ZSgnEffE, // the modified Z sign
output logic PSgnE, output logic PSgnE, // the product's sign
output logic [8:0] NormCntE output logic [8:0] NormCntE // normalization shift cnt
); );
logic [`NE-1:0] Denorm;
logic [`NE-1:0] DenormXExp, DenormYExp; // Denormalized input value
logic [`NE-1:0] Denorm; // value of a denormaized number based on precision
logic [`NE-1:0] XExpVal, YExpVal; // Exponent value after taking into account denormals
logic [2*`NF+1:0] ProdManE; // 1.X frac * 1.Y frac in U(2.2Nf) format logic [2*`NF+1:0] ProdManE; // 1.X frac * 1.Y frac in U(2.2Nf) format
logic [3*`NF+5:0] AlignedAddendE; // Z aligned for addition in U(NF+5.2NF+1) logic [3*`NF+5:0] AlignedAddendE; // Z aligned for addition in U(NF+5.2NF+1)
@ -123,82 +119,24 @@ module fma1(
// Calculate the product // Calculate the product
// - When multipliying two fp numbers, add the exponents // - When multipliying two fp numbers, add the exponents
// - Subtract the bias (XExp + YExp has two biases, one from each exponent) // - Subtract the bias (XExp + YExp has two biases, one from each exponent)
// - Denormal numbers have an an exponent value of 1, however they are // - If the product is zero then kill the exponent - this is a problem
// represented with an exponent of 0. add one if there is a denormal number
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// denormalized numbers have diffrent values depending on which precison it is. // denormalized numbers have diffrent values depending on which precison it is.
// double - 1
// single - 1024-128+1 = 897
assign Denorm = FmtE ? 1 : 897; assign Denorm = FmtE ? 1 : 897;
assign DenormXExp = XDenormE ? Denorm : XExpE; assign XExpVal = XDenormE ? Denorm : XExpE;
assign DenormYExp = YDenormE ? Denorm : YExpE; assign YExpVal = YDenormE ? Denorm : YExpE;
assign ProdExpE = (DenormXExp + DenormYExp - BiasE)&{`NE+2{~(XZeroE|YZeroE)}}; // take into account if the product is zero, the product's exponent does not compute properly if X or Y is zero
assign ProdExpE = (XExpVal + YExpVal - BiasE)&{`NE+2{~(XZeroE|YZeroE)}};
// Calculate the product's mantissa // multiplication of the mantissa's
// - Mantissa includes the assumed one. If the number is denormalized or zero, it does not have an assumed one.
// assign ProdManE = XManE * YManE;
mult mult(.XManE, .YManE, .ProdManE); mult mult(.XManE, .YManE, .ProdManE);
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // Alignment shifter // Alignment shifter
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // determine the shift count for alignment
// // - negitive means Z is larger, so shift Z left
// // - positive means the product is larger, so shift Z right
// // - Denormal numbers have an an exponent value of 1, however they are
// // represented with an exponent of 0. add one to the exponent if it is a denormal number
// assign AlignCnt = ProdExpE - (ZExpE + ({`NE-1{ZDenormE}}&Denorm));
// // Defualt Addition without shifting
// // | 54'b0 | 106'b(product) | 2'b0 |
// // |1'b0| addnend |
// // the 1'b0 before the added is because the product's mantissa has two bits before the binary point (xx.xxxxxxxxxx...)
// assign ZManPreShifted = {(`NF+3)'(0), ZManE, /*106*/(2*`NF+2)'(0)};
// always_comb
// begin
// // If the product is too small to effect the sum, kill the product
// // | 54'b0 | 106'b(product) | 2'b0 |
// // | addnend |
// if ($signed(AlignCnt) <= $signed(-(`NF+4))) begin
// KillProdE = 1;
// ZManShifted = ZManPreShifted;//{107'b0, XManE, 54'b0};
// AddendStickyE = ~(XZeroE|YZeroE);
// // If the Addend is shifted left (negitive AlignCnt)
// // | 54'b0 | 106'b(product) | 2'b0 |
// // | addnend |
// end else if($signed(AlignCnt) <= $signed(0)) begin
// KillProdE = 0;
// ZManShifted = ZManPreShifted << -AlignCnt;
// AddendStickyE = |(ZManShifted[`NF-1:0]);
// // If the Addend is shifted right (positive AlignCnt)
// // | 54'b0 | 106'b(product) | 2'b0 |
// // | addnend |
// end else if ($signed(AlignCnt)<=$signed(2*`NF+1)) begin
// KillProdE = 0;
// ZManShifted = ZManPreShifted >> AlignCnt;
// AddendStickyE = |(ZManShifted[`NF-1:0]);
// // If the addend is too small to effect the addition
// // - The addend has to shift two past the end of the addend to be considered too small
// // - The 2 extra bits are needed for rounding
// // | 54'b0 | 106'b(product) | 2'b0 |
// // | addnend |
// end else begin
// KillProdE = 0;
// ZManShifted = 0;
// AddendStickyE = ~ZZeroE;
// end
// end
// assign AlignedAddendE = ZManShifted[4*`NF+5:`NF];
alignshift alignshift(.ZExpE, .ZManE, .ZDenormE, .XZeroE, .YZeroE, .ZZeroE, .ProdExpE, .Denorm, alignshift alignshift(.ZExpE, .ZManE, .ZDenormE, .XZeroE, .YZeroE, .ZZeroE, .ProdExpE, .Denorm,
.AlignedAddendE, .AddendStickyE, .KillProdE); .AlignedAddendE, .AddendStickyE, .KillProdE);
@ -209,22 +147,39 @@ module fma1(
assign PSgnE = XSgnE ^ YSgnE ^ (FOpCtrlE[1]&~FOpCtrlE[2]); assign PSgnE = XSgnE ^ YSgnE ^ (FOpCtrlE[1]&~FOpCtrlE[2]);
assign ZSgnEffE = ZSgnE^FOpCtrlE[0]; // Swap sign of Z for subtract assign ZSgnEffE = ZSgnE^FOpCtrlE[0]; // Swap sign of Z for subtract
// ///////////////////////////////////////////////////////////////////////////////
// // Addition/LZA
// ///////////////////////////////////////////////////////////////////////////////
fmaadd fmaadd(.AlignedAddendE, .ProdManE, .PSgnE, .ZSgnEffE, .KillProdE, .SumE, .NegSumE, .InvZE, .NormCntE, .XZeroE, .YZeroE); fmaadd fmaadd(.AlignedAddendE, .ProdManE, .PSgnE, .ZSgnEffE, .KillProdE, .SumE, .NegSumE, .InvZE, .NormCntE, .XZeroE, .YZeroE);
endmodule endmodule
module fma2( module fma2(
input logic XSgnM, YSgnM, input logic XSgnM, YSgnM, // input signs
input logic [`NE-1:0] XExpM, YExpM, ZExpM, input logic [`NE-1:0] XExpM, YExpM, ZExpM, // input exponents
input logic [`NF:0] XManM, YManM, ZManM, input logic [`NF:0] XManM, YManM, ZManM, // input mantissas
input logic [2:0] FrmM, // rounding mode 000 = rount to nearest, ties to even 001 = round twords zero 010 = round down 011 = round up 100 = round to nearest, ties to max magnitude input logic [2:0] FrmM, // rounding mode 000 = rount to nearest, ties to even 001 = round twords zero 010 = round down 011 = round up 100 = round to nearest, ties to max magnitude
input logic [2:0] FOpCtrlM, // 000 = fmadd (X*Y)+Z, 001 = fmsub (X*Y)-Z, 010 = fnmsub -(X*Y)+Z, 011 = fnmadd -(X*Y)-Z, 100 = fmul (X*Y)
input logic FmtM, // precision 1 = double 0 = single input logic FmtM, // precision 1 = double 0 = single
// input logic [2*`NF+1:0] ProdManM, // 1.X frac * 1.Y frac
// input logic [3*`NF+5:0] AlignedAddendM, // Z aligned for addition
input logic [`NE+1:0] ProdExpM, // X exponent + Y exponent - bias input logic [`NE+1:0] ProdExpM, // X exponent + Y exponent - bias
input logic AddendStickyM, // sticky bit that is calculated during alignment input logic AddendStickyM, // sticky bit that is calculated during alignment
input logic KillProdM, // set the product to zero before addition if the product is too small to matter input logic KillProdM, // set the product to zero before addition if the product is too small to matter
@ -232,12 +187,12 @@ module fma2(
input logic XInfM, YInfM, ZInfM, // inputs are infinity input logic XInfM, YInfM, ZInfM, // inputs are infinity
input logic XNaNM, YNaNM, ZNaNM, // inputs are NaN input logic XNaNM, YNaNM, ZNaNM, // inputs are NaN
input logic XSNaNM, YSNaNM, ZSNaNM, // inputs are signaling NaNs input logic XSNaNM, YSNaNM, ZSNaNM, // inputs are signaling NaNs
input logic [3*`NF+5:0] SumM, input logic [3*`NF+5:0] SumM, // the positive sum
input logic NegSumM, input logic NegSumM, // was the sum negitive
input logic InvZM, input logic InvZM, // do you invert Z
input logic ZSgnEffM, input logic ZSgnEffM, // the modified Z sign - depends on instruction
input logic PSgnM, input logic PSgnM, // the product's sign
input logic [8:0] NormCntM, input logic [8:0] NormCntM, // the normalization shift count
output logic [`FLEN-1:0] FMAResM, // FMA final result output logic [`FLEN-1:0] FMAResM, // FMA final result
output logic [4:0] FMAFlgM); // FMA flags {invalid, divide by zero, overflow, underflow, inexact} output logic [4:0] FMAFlgM); // FMA flags {invalid, divide by zero, overflow, underflow, inexact}
@ -246,199 +201,45 @@ module fma2(
logic [`NF-1:0] ResultFrac; // Result fraction logic [`NF-1:0] ResultFrac; // Result fraction
logic [`NE-1:0] ResultExp; // Result exponent logic [`NE-1:0] ResultExp; // Result exponent
logic ResultSgn; // Result sign logic ResultSgn; // Result sign
// logic PSgn; // product sign
// logic [2*`NF+1:0] ProdMan2; // product being added
// logic [3*`NF+6:0] AlignedAddend2; // possibly inverted aligned Z
// logic [3*`NF+5:0] Sum; // positive sum
// logic [3*`NF+6:0] PreSum; // possibly negitive sum
logic [`NE+1:0] SumExp; // exponent of the normalized sum logic [`NE+1:0] SumExp; // exponent of the normalized sum
// logic [`NE+1:0] SumExpTmp; // exponent of the normalized sum not taking into account denormal or zero results
// logic [`NE+1:0] SumExpTmpMinus1; // SumExpTmp-1
logic [`NE+1:0] FullResultExp; // ResultExp with bits to determine sign and overflow logic [`NE+1:0] FullResultExp; // ResultExp with bits to determine sign and overflow
logic [`NF+2:0] NormSum; // normalized sum logic [`NF+2:0] NormSum; // normalized sum
// logic [3*`NF+5:0] SumShifted; // sum shifted for normalization
// logic [8:0] NormCnt; // output of the leading zero detector //***change this later
logic NormSumSticky; // sticky bit calulated from the normalized sum logic NormSumSticky; // sticky bit calulated from the normalized sum
logic SumZero; // is the sum zero logic SumZero; // is the sum zero
// logic NegSum; // is the sum negitive
// logic InvZ; // invert Z if there is a subtraction (-product + Z or product - Z)
logic ResultDenorm; // is the result denormalized logic ResultDenorm; // is the result denormalized
logic Sticky, UfSticky; // Sticky bit logic Sticky, UfSticky; // Sticky bit
logic Plus1, Minus1, CalcPlus1, CalcMinus1; // do you add or subtract one for rounding logic Plus1, Minus1, CalcPlus1; // do you add or subtract one for rounding
logic UfPlus1, UfCalcPlus1; // do you add one (for determining underflow flag) logic UfPlus1; // do you add one (for determining underflow flag)
logic Invalid,Underflow,Overflow,Inexact; // flags logic Invalid,Underflow,Overflow; // flags
// logic [8:0] DenormShift; // right shift if the result is denormalized //***change this later
// logic SubBySmallNum; // was there supposed to be a subtraction by a small number
logic [`FLEN-1:0] Addend; // value to add (Z or zero)
logic ZeroSgn; // the result's sign if the sum is zero logic ZeroSgn; // the result's sign if the sum is zero
logic ResultSgnTmp; // the result's sign assuming the result is not zero logic ResultSgnTmp; // the result's sign assuming the result is not zero
logic Guard, Round, LSBNormSum; // bits needed to determine rounding logic Guard, Round; // bits needed to determine rounding
logic UfGuard, UfRound, UfLSBNormSum; // bits needed to determine rounding for underflow flag logic UfRound, UfLSBNormSum; // bits needed to determine rounding for underflow flag
// logic [`NE+1:0] MaxExp; // maximum value of the exponent
// logic [`NE+1:0] FracLen; // length of the fraction
logic SigNaN; // is an input a signaling NaN
logic UnderflowFlag; // Underflow singal used in FMAFlgM (used to avoid a circular depencency)
logic [`FLEN-1:0] XNaNResult, YNaNResult, ZNaNResult, InvalidResult, OverflowResult, KillProdResult, UnderflowResult; // possible results logic [`FLEN-1:0] XNaNResult, YNaNResult, ZNaNResult, InvalidResult, OverflowResult, KillProdResult, UnderflowResult; // possible results
//logic ZSgnEffM;
// ///////////////////////////////////////////////////////////////////////////////
// // Addition
// ///////////////////////////////////////////////////////////////////////////////
// // Negate Z when doing one of the following opperations: ///////////////////////////////////////////////////////////////////////////////
// // -prod + Z // Normalization
// // prod - Z ///////////////////////////////////////////////////////////////////////////////
// assign ZSgnEffM = ZSgnM^FOpCtrlM[0]; // Swap sign of Z for subtract
// assign InvZ = ZSgnEffM ^ PSgn;
// // Choose an inverted or non-inverted addend - the one is added later
// assign AlignedAddend2 = InvZ ? ~{1'b0, AlignedAddendM} : {1'b0, AlignedAddendM};
// // Kill the product if the product is too small to effect the addition (determined in fma1.sv)
// assign ProdMan2 = KillProdM ? 0 : ProdManM;
// // Do the addition
// // - add one to negate if the added was inverted
// // - the 2 extra bits at the begining and end are needed for rounding
// assign PreSum = AlignedAddend2 + {ProdMan2, 2'b0} + InvZ;
// // Is the sum negitive
// assign NegSum = PreSum[3*`NF+6];
// // If the sum is negitive, negate the sum.
// assign Sum = NegSum ? -PreSum[3*`NF+5:0] : PreSum[3*`NF+5:0];
// ///////////////////////////////////////////////////////////////////////////////
// // Normalization
// ///////////////////////////////////////////////////////////////////////////////
// // Determine if the sum is zero
// assign SumZero = ~(|Sum);
// // determine the length of the fraction based on precision
// assign FracLen = FmtM ? `NF : 13'd23;
// //assign FracLen = `NF;
// // Determine if the result is denormal
// logic [`NE+1:0] SumExpTmpTmp;
// assign SumExpTmpTmp = KillProdM ? {2'b0, ZExpM} : ProdExpM + -({4'b0, NormCnt} - (`NF+4));
// assign SumExpTmp = FmtM ? SumExpTmpTmp : (SumExpTmpTmp-1023+127)&{`NE+2{|SumExpTmpTmp}};
// assign ResultDenorm = $signed(SumExpTmp)<=0 & ($signed(SumExpTmp)>=$signed(-FracLen)) & ~SumZero;
// // Determine the shift needed for denormal results
// assign SumExpTmpMinus1 = SumExpTmp-1;
// assign DenormShift = ResultDenorm ? SumExpTmpMinus1[8:0] : 0; //*** change this when changing the size of DenormShift also change to an and opperation
// // Normalize the sum
// assign SumShifted = SumZero ? 0 : Sum << NormCnt+DenormShift; //*** fix mux's with constants in them
// assign NormSum = SumShifted[3*`NF+5:2*`NF+3];
// // Calculate the sticky bit
// assign NormSumSticky = FmtM ? (|SumShifted[2*`NF+3:0]) : (|SumShifted[136:0]);
// assign Sticky = AddendStickyM | NormSumSticky;
// // Determine sum's exponent
// assign SumExp = SumZero ? 0 : //***again fix mux
// ResultDenorm ? 0 :
// SumExpTmp;
normalize normalize(.SumM, .ZExpM, .ProdExpM, .NormCntM, .FmtM, .KillProdM, .AddendStickyM, .NormSum, normalize normalize(.SumM, .ZExpM, .ProdExpM, .NormCntM, .FmtM, .KillProdM, .AddendStickyM, .NormSum,
.SumZero, .NormSumSticky, .UfSticky, .SumExp, .ResultDenorm); .SumZero, .NormSumSticky, .UfSticky, .SumExp, .ResultDenorm);
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // Rounding // Rounding
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // round to nearest even // round to nearest even
// // {Guard, Round, Sticky} // round to zero
// // 0xx - do nothing // round to -infinity
// // 100 - tie - Plus1 if result is odd (LSBNormSum = 1) // round to infinity
// // - don't add 1 if a small number was supposed to be subtracted // round to nearest max magnitude
// // 101 - do nothing if a small number was supposed to subtracted (the sticky bit was set by the small number)
// // 110/111 - Plus1
// // round to zero - subtract 1 if a small number was supposed to be subtracted from a positive result with guard and round bits of 0
// // round to -infinity
// // - Plus1 if negative unless a small number was supposed to be subtracted from a result with guard and round bits of 0
// // - subtract 1 if a small number was supposed to be subtracted from a positive result with guard and round bits of 0
// // round to infinity
// // - Plus1 if positive unless a small number was supposed to be subtracted from a result with guard and round bits of 0
// // - subtract 1 if a small number was supposed to be subtracted from a negative result with guard and round bits of 0
// // round to nearest max magnitude
// // {Guard, Round, Sticky}
// // 0xx - do nothing
// // 100 - tie - Plus1
// // - don't add 1 if a small number was supposed to be subtracted
// // 101 - do nothing if a small number was supposed to subtracted (the sticky bit was set by the small number)
// // 110/111 - Plus1
// // determine guard, round, and least significant bit of the result
// assign Guard = FmtM ? NormSum[2] : NormSum[31];
// assign Round = FmtM ? NormSum[1] : NormSum[30];
// assign LSBNormSum = FmtM ? NormSum[3] : NormSum[32];
// // used to determine underflow flag
// assign UfGuard = FmtM ? NormSum[1] : NormSum[30];
// assign UfRound = FmtM ? NormSum[0] : NormSum[29];
// assign UfLSBNormSum = FmtM ? NormSum[2] : NormSum[31];
// // Deterimine if a small number was supposed to be subtrated
// assign SubBySmallNum = AddendStickyM & InvZ & ~(NormSumSticky) & ~ZZeroM;
// always_comb begin
// // Determine if you add 1
// case (FrmM)
// 3'b000: CalcPlus1 = Guard & (Round | ((Sticky|UfRound)&~(~Round&SubBySmallNum)) | (~Round&~(Sticky|UfRound)&LSBNormSum&~SubBySmallNum));//round to nearest even
// 3'b001: CalcPlus1 = 0;//round to zero
// 3'b010: CalcPlus1 = ResultSgn & ~(SubBySmallNum & ~Guard & ~Round);//round down
// 3'b011: CalcPlus1 = ~ResultSgn & ~(SubBySmallNum & ~Guard & ~Round);//round up
// 3'b100: CalcPlus1 = (Guard & (Round | ((Sticky|UfRound)&~(~Round&SubBySmallNum)) | (~Round&~(Sticky|UfRound)&~SubBySmallNum)));//round to nearest max magnitude
// default: CalcPlus1 = 1'bx;
// endcase
// // Determine if you add 1 (for underflow flag)
// case (FrmM)
// 3'b000: UfCalcPlus1 = UfGuard & (UfRound | (Sticky&~(~UfRound&SubBySmallNum)) | (~UfRound&~Sticky&UfLSBNormSum&~SubBySmallNum));//round to nearest even
// 3'b001: UfCalcPlus1 = 0;//round to zero
// 3'b010: UfCalcPlus1 = ResultSgn & ~(SubBySmallNum & ~UfGuard & ~UfRound);//round down
// 3'b011: UfCalcPlus1 = ~ResultSgn & ~(SubBySmallNum & ~UfGuard & ~UfRound);//round up
// 3'b100: UfCalcPlus1 = (UfGuard & (UfRound | (Sticky&~(~UfRound&SubBySmallNum)) | (~UfRound&~Sticky&~SubBySmallNum)));//round to nearest max magnitude
// default: UfCalcPlus1 = 1'bx;
// endcase
// // Determine if you subtract 1
// case (FrmM)
// 3'b000: CalcMinus1 = 0;//round to nearest even
// 3'b001: CalcMinus1 = SubBySmallNum & ~Guard & ~Round;//round to zero
// 3'b010: CalcMinus1 = ~ResultSgn & ~Guard & ~Round & SubBySmallNum;//round down
// 3'b011: CalcMinus1 = ResultSgn & ~Guard & ~Round & SubBySmallNum;//round up
// 3'b100: CalcMinus1 = 0;//round to nearest max magnitude
// default: CalcMinus1 = 1'bx;
// endcase
// end
// // If an answer is exact don't round
// assign Plus1 = CalcPlus1 & (Sticky | UfGuard | Guard | Round);
// assign UfPlus1 = UfCalcPlus1 & (Sticky | UfGuard | UfRound);
// assign Minus1 = CalcMinus1 & (Sticky | UfGuard | Guard | Round);
// // Compute rounded result
// logic [`FLEN:0] RoundAdd; //*** move this up
// logic [`NF-1:0] NormSumTruncated;
// assign RoundAdd = FmtM ? Minus1 ? {`FLEN+1{1'b1}} : {{{`FLEN{1'b0}}}, Plus1} :
// Minus1 ? {{36{1'b1}}, 29'b0} : {35'b0, Plus1, 29'b0};
// assign NormSumTruncated = FmtM ? NormSum[`NF+2:3] : {NormSum[54:32], 29'b0};
// assign {FullResultExp, ResultFrac} = {SumExp, NormSumTruncated} + RoundAdd;
// assign ResultExp = FullResultExp[`NE-1:0];
fmaround fmaround(.FmtM, .FrmM, .Sticky, .UfSticky, .NormSum, .AddendStickyM, .NormSumSticky, .ZZeroM, .InvZM, .ResultSgn, .SumExp, fmaround fmaround(.FmtM, .FrmM, .Sticky, .UfSticky, .NormSum, .AddendStickyM, .NormSumSticky, .ZZeroM, .InvZM, .ResultSgn, .SumExp,
.CalcPlus1, .Plus1, .UfPlus1, .Minus1, .FullResultExp, .ResultFrac, .ResultExp, .Round, .Guard, .UfRound, .UfLSBNormSum); .CalcPlus1, .Plus1, .UfPlus1, .Minus1, .FullResultExp, .ResultFrac, .ResultExp, .Round, .Guard, .UfRound, .UfLSBNormSum);
@ -467,38 +268,9 @@ module fma2(
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // Flags // Flags
// /////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// // Set Invalid flag for following cases:
// // 1) any input is a signaling NaN
// // 2) Inf - Inf (unless x or y is NaN)
// // 3) 0 * Inf
// assign MaxExp = FmtM ? {`NE{1'b1}} : {8{1'b1}};
// assign SigNaN = XSNaNM | YSNaNM | ZSNaNM;
// assign Invalid = SigNaN | ((XInfM || YInfM) & ZInfM & (PSgn ^ ZSgnEffM) & ~XNaNM & ~YNaNM) | (XZeroM & YInfM) | (YZeroM & XInfM);
// // Set Overflow flag if the number is too big to be represented
// // - Don't set the overflow flag if an overflowed result isn't outputed
// assign Overflow = FullResultExp >= {MaxExp} & ~FullResultExp[`NE+1]&~(XNaNM|YNaNM|ZNaNM|XInfM|YInfM|ZInfM);
// // Set Underflow flag if the number is too small to be represented in normal numbers
// // - Don't set the underflow flag if the result is exact
// assign Underflow = (SumExp[`NE+1] | ((SumExp == 0) & (Round|Guard|Sticky|UfRound)))&~(XNaNM|YNaNM|ZNaNM|XInfM|YInfM|ZInfM);
// assign UnderflowFlag = (FullResultExp[`NE+1] | ((FullResultExp == 0) | ((FullResultExp == 1) & (SumExp == 0) & ~(UfPlus1&UfLSBNormSum)))&(Round|Guard|Sticky))&~(XNaNM|YNaNM|ZNaNM|XInfM|YInfM|ZInfM);
// // Set Inexact flag if the result is diffrent from what would be outputed given infinite precision
// // - Don't set the underflow flag if an underflowed result isn't outputed
// assign Inexact = (Sticky|UfRound|Overflow|Guard|Round|Underflow)&~(XNaNM|YNaNM|ZNaNM|XInfM|YInfM|ZInfM);
// // Combine flags
// // - FMA can't set the Divide by zero flag
// // - Don't set the underflow flag if the result was rounded up to a normal number
// assign FMAFlgM = {Invalid, 1'b0, Overflow, UnderflowFlag, Inexact};
fmaflags fmaflags(.XSNaNM, .YSNaNM, .ZSNaNM, .XInfM, .YInfM, .ZInfM, .XZeroM, .YZeroM, fmaflags fmaflags(.XSNaNM, .YSNaNM, .ZSNaNM, .XInfM, .YInfM, .ZInfM, .XZeroM, .YZeroM,
.XNaNM, .YNaNM, .ZNaNM, .FullResultExp, .SumExp, .ZSgnEffM, .PSgnM, .Round, .Guard, .UfRound, .UfLSBNormSum, .Sticky, .UfPlus1, .XNaNM, .YNaNM, .ZNaNM, .FullResultExp, .SumExp, .ZSgnEffM, .PSgnM, .Round, .Guard, .UfRound, .UfLSBNormSum, .Sticky, .UfPlus1,
@ -523,7 +295,7 @@ module fma2(
assign FMAResM = XNaNM ? XNaNResult : assign FMAResM = XNaNM ? XNaNResult :
YNaNM ? YNaNResult : YNaNM ? YNaNResult :
ZNaNM ? ZNaNResult : ZNaNM ? ZNaNResult :
Invalid ? InvalidResult : // has to be before inf Invalid ? InvalidResult :
XInfM ? FmtM ? {PSgnM, XExpM, XManM[`NF-1:0]} : {{32{1'b1}}, PSgnM, XExpM[7:0], XManM[51:29]} : XInfM ? FmtM ? {PSgnM, XExpM, XManM[`NF-1:0]} : {{32{1'b1}}, PSgnM, XExpM[7:0], XManM[51:29]} :
YInfM ? FmtM ? {PSgnM, YExpM, YManM[`NF-1:0]} : {{32{1'b1}}, PSgnM, YExpM[7:0], YManM[51:29]} : YInfM ? FmtM ? {PSgnM, YExpM, YManM[`NF-1:0]} : {{32{1'b1}}, PSgnM, YExpM[7:0], YManM[51:29]} :
ZInfM ? FmtM ? {ZSgnEffM, ZExpM, ZManM[`NF-1:0]} : {{32{1'b1}}, ZSgnEffM, ZExpM[7:0], ZManM[51:29]} : ZInfM ? FmtM ? {ZSgnEffM, ZExpM, ZManM[`NF-1:0]} : {{32{1'b1}}, ZSgnEffM, ZExpM[7:0], ZManM[51:29]} :
@ -537,6 +309,11 @@ module fma2(
endmodule endmodule
module mult( module mult(
input logic [`NF:0] XManE, YManE, input logic [`NF:0] XManE, YManE,
output logic [2*`NF+1:0] ProdManE output logic [2*`NF+1:0] ProdManE
@ -544,22 +321,26 @@ module mult(
assign ProdManE = XManE * YManE; assign ProdManE = XManE * YManE;
endmodule endmodule
module alignshift( module alignshift(
input logic [`NE-1:0] ZExpE, // biased exponents in B(NE.0) format input logic [`NE-1:0] ZExpE, // biased exponents in B(NE.0) format
input logic [`NF:0] ZManE, // fractions in U(0.NF) format] input logic [`NF:0] ZManE, // fractions in U(0.NF) format]
input logic ZDenormE, // is the input denormal input logic ZDenormE, // is the input denormal
input logic XZeroE, YZeroE, ZZeroE, // is the input zero input logic XZeroE, YZeroE, ZZeroE, // is the input zero
input logic [`NE+1:0] ProdExpE, input logic [`NE+1:0] ProdExpE, // the product's exponent
input logic [`NE-1:0] Denorm, input logic [`NE-1:0] Denorm, // the biased value of a denormalized number
output logic [3*`NF+5:0] AlignedAddendE, output logic [3*`NF+5:0] AlignedAddendE, // Z aligned for addition in U(NF+5.2NF+1)
output logic AddendStickyE, output logic AddendStickyE, // Sticky bit calculated from the aliged addend
output logic KillProdE output logic KillProdE // should the product be set to zero
); );
logic [`NE+1:0] AlignCnt; // how far to shift the addend to align with the product in Q(NE+2.0) format logic [`NE+1:0] AlignCnt; // how far to shift the addend to align with the product in Q(NE+2.0) format
logic [4*`NF+5:0] ZManShifted; // output of the alignment shifter including sticky bits U(NF+5.3NF+1) logic [4*`NF+5:0] ZManShifted; // output of the alignment shifter including sticky bits U(NF+5.3NF+1)
logic [4*`NF+5:0] ZManPreShifted; // input to the alignment shifter U(NF+5.3NF+1) logic [4*`NF+5:0] ZManPreShifted; // input to the alignment shifter U(NF+5.3NF+1)
logic [`NE-1:0] DenormZExp; logic [`NE-1:0] ZExpVal; // Exponent value after taking into account denormals
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Alignment shifter // Alignment shifter
@ -568,14 +349,13 @@ module alignshift(
// determine the shift count for alignment // determine the shift count for alignment
// - negitive means Z is larger, so shift Z left // - negitive means Z is larger, so shift Z left
// - positive means the product is larger, so shift Z right // - positive means the product is larger, so shift Z right
// - Denormal numbers have an an exponent value of 1, however they are // - Denormal numbers have a diffrent exponent value depending on the precision
// represented with an exponent of 0. add one to the exponent if it is a denormal number assign ZExpVal = ZDenormE ? Denorm : ZExpE;
assign DenormZExp = ZDenormE ? Denorm : ZExpE; assign AlignCnt = ProdExpE - ZExpVal + (`NF+3);
assign AlignCnt = ProdExpE - DenormZExp + (`NF+3);
// Defualt Addition without shifting // Defualt Addition without shifting
// | 54'b0 | 106'b(product) | 2'b0 | // | 54'b0 | 106'b(product) | 2'b0 |
// |1'b0| addnend | // | addnend |
// the 1'b0 before the added is because the product's mantissa has two bits before the binary point (xx.xxxxxxxxxx...) // the 1'b0 before the added is because the product's mantissa has two bits before the binary point (xx.xxxxxxxxxx...)
assign ZManPreShifted = {ZManE,(3*`NF+5)'(0)}; assign ZManPreShifted = {ZManE,(3*`NF+5)'(0)};
@ -588,20 +368,10 @@ module alignshift(
// | addnend | // | addnend |
if ($signed(AlignCnt) < $signed(0)) begin if ($signed(AlignCnt) < $signed(0)) begin
KillProdE = 1; KillProdE = 1;
ZManShifted = ZManPreShifted;//{107'b0, XManE, 54'b0}; ZManShifted = ZManPreShifted;
AddendStickyE = ~(XZeroE|YZeroE); AddendStickyE = ~(XZeroE|YZeroE);
// // If the Addend is shifted left (negitive AlignCnt) // If the Addend is shifted right
// // | 54'b0 | 106'b(product) | 2'b0 |
// // | addnend |
// end else if($signed(AlignCnt) <= $signed(0)) begin
// KillProdE = 0;
// ZManShifted = ZManPreShifted << -AlignCnt;
// AddendStickyE = |(ZManShifted[`NF-1:0]);
// If the Addend is shifted right (positive AlignCnt)
// | 54'b0 | 106'b(product) | 2'b0 | // | 54'b0 | 106'b(product) | 2'b0 |
// | addnend | // | addnend |
end else if ($signed(AlignCnt)<=$signed(3*`NF+4)) begin end else if ($signed(AlignCnt)<=$signed(3*`NF+4)) begin
@ -622,25 +392,27 @@ module alignshift(
end end
end end
assign AlignedAddendE = ZManShifted[4*`NF+5:`NF]; assign AlignedAddendE = ZManShifted[4*`NF+5:`NF];
endmodule endmodule
module fmaadd( module fmaadd(
input logic [3*`NF+5:0] AlignedAddendE, // Z aligned for addition input logic [3*`NF+5:0] AlignedAddendE, // Z aligned for addition in U(NF+5.2NF+1)
input logic [2*`NF+1:0] ProdManE, input logic [2*`NF+1:0] ProdManE, // the product's mantissa
input logic PSgnE, ZSgnEffE, input logic PSgnE, ZSgnEffE,// the product and modified Z signs
input logic KillProdE, input logic KillProdE, // should the product be set to 0
input logic XZeroE, YZeroE, input logic XZeroE, YZeroE, // is the input zero
output logic [3*`NF+5:0] SumE, output logic [3*`NF+5:0] SumE, // the positive sum
output logic NegSumE, output logic NegSumE, // was the sum negitive
output logic InvZE, output logic InvZE, // do you invert Z
output logic [8:0] NormCntE output logic [8:0] NormCntE // normalization shift count
); );
logic [3*`NF+6:0] PreSum, NegPreSum; // possibly negitive sum logic [3*`NF+6:0] PreSum, NegPreSum; // possibly negitive sum
logic [2*`NF+1:0] ProdMan2; // product being added logic [2*`NF+1:0] ProdMan2; // product being added
logic [3*`NF+6:0] AlignedAddend2; // possibly inverted aligned Z logic [3*`NF+6:0] AlignedAddend2; // possibly inverted aligned Z
logic [3*`NF+6:0] NegProdMan2; logic [3*`NF+6:0] NegProdMan2; // a negated ProdMan2
logic [8:0] PNormCnt, NNormCnt; logic [8:0] PNormCnt, NNormCnt; // results from the LZA
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Addition // Addition
@ -651,83 +423,46 @@ module fmaadd(
// prod - Z // prod - Z
assign InvZE = ZSgnEffE ^ PSgnE; assign InvZE = ZSgnEffE ^ PSgnE;
// Choose an inverted or non-inverted addend - the one is added later // Choose an inverted or non-inverted addend - the one has to be added now for the LZA
assign AlignedAddend2 = InvZE ? -{1'b0, AlignedAddendE} : {1'b0, AlignedAddendE}; assign AlignedAddend2 = InvZE ? -{1'b0, AlignedAddendE} : {1'b0, AlignedAddendE};
// Kill the product if the product is too small to effect the addition (determined in fma1.sv) // Kill the product if the product is too small to effect the addition (determined in fma1.sv)
assign ProdMan2 = ProdManE&{2*`NF+2{~KillProdE}}; assign ProdMan2 = ProdManE&{2*`NF+2{~KillProdE}};
// Negate ProdMan for LZA and the negitive sum calculation
assign NegProdMan2 = {{`NF+3{~(XZeroE|YZeroE|KillProdE)}}, -ProdMan2, 2'b0}; assign NegProdMan2 = {{`NF+3{~(XZeroE|YZeroE|KillProdE)}}, -ProdMan2, 2'b0};
// LZAs one for the positive result and one for the negitive
// - the +1 from inverting causes problems for normalization
poslza poslza(AlignedAddend2, ProdMan2, PNormCnt); poslza poslza(AlignedAddend2, ProdMan2, PNormCnt);
neglza neglza({1'b0,AlignedAddendE}, NegProdMan2, NNormCnt); neglza neglza({1'b0,AlignedAddendE}, NegProdMan2, NNormCnt);
// Do the addition // Do the addition
// - add one to negate if the added was inverted // - calculate a positive and negitive sum in parallel
// - the 2 extra bits at the begining and end are needed for rounding
assign PreSum = AlignedAddend2 + {ProdMan2, 2'b0}; assign PreSum = AlignedAddend2 + {ProdMan2, 2'b0};
assign NegPreSum = AlignedAddendE + NegProdMan2; assign NegPreSum = AlignedAddendE + NegProdMan2;
// Is the sum negitive // Is the sum negitive
assign NegSumE = PreSum[3*`NF+6]; assign NegSumE = PreSum[3*`NF+6];
// If the sum is negitive, negate the sum. // Choose the positive sum and accompanying LZA result.
assign SumE = NegSumE ? NegPreSum[3*`NF+5:0] : PreSum[3*`NF+5:0]; assign SumE = NegSumE ? NegPreSum[3*`NF+5:0] : PreSum[3*`NF+5:0];
assign NormCntE = NegSumE ? NNormCnt : PNormCnt; assign NormCntE = NegSumE ? NNormCnt : PNormCnt;
// set to PNormCnt if the product is zero (there may be an additional bit of error from the negation)
endmodule endmodule
// module fmalzc(
// input logic [3*`NF+5:0] Sum,
// output logic [8:0] NormCntCheck
// );
// ///////////////////////////////////////////////////////////////////////////////
// // Leading one detector
// ///////////////////////////////////////////////////////////////////////////////
// //*** replace with non-behavoral code
// logic [8:0] i;
// always_comb begin
// i = 0;
// while (~Sum[3*`NF+5-i] && $unsigned(i) <= $unsigned(3*`NF+5)) i = i+1; // search for leading one
// NormCntCheck = i;
// end
// endmodule
////////////////////////////////////////////////////////////////////////////////////
// Filename: lza.v
// Author: Katherine Parry
// Date: 2021/02/07
//
// Description: Leading Zero Anticipator
// This a the Kershaw Leading Zero Anticipator(LZA) using the algorithm described in
// "Leading Zero Anticipation and Dectection - A Comparison of Methods" (2001)
// Schmookler and Nowka.
// After swapping, alignment and inversion of A & B, the following functions are
// applied to all 'i' bits.
// -- T[i] = A[i] XOR B[i]; // Propagation that will occur
// -- G[i] = A[i] AND B[i]; // The value Generated
// -- Z[i] = ~(A[i] OR B[i]): // Fill functions
// The leading Zero is determined by the first occurance of the pattern T*GGZ*,
// whereas Leading ones are found by the pattern T*ZG*
// To evaluate the pattern we map it to the function that evaluates the three bits
// (current, before, & after):
// f[i] = T[i-1](G[i]~Z[i+1] & ~G[i+1]Z[i]) | ~T[i-1](Z[i]~Z[i+1] & G[i]~G[i+1])
//
////////////////////////////////////////////////////////////////////////////////////
module poslza( module poslza(
// parameter SIGNIFICANT_SZ=52; input logic [3*`NF+6:0] A, // addend
//leading digit anticipator input logic [2*`NF+1:0] P, // product
// localparam sz=SIGNIFICANT_SZ+1; output logic [8:0] PCnt // normalization shift count for the positive result
input logic [3*`NF+6:0] A,
input logic [2*`NF+1:0] P,
output logic [8:0] PCnt
); );
// Compute Generate, Propageate and Kill for each bit
// calculate the propagate (T) and kill (Z) bits
logic [3*`NF+6:0] T; logic [3*`NF+6:0] T;
logic [3*`NF+5:0] Z; logic [3*`NF+5:0] Z;
// assign T = A^{{`NF+3{1'b0}}, P, 2'b0};
// assign Z = ~(A|{{`NF+3{1'b0}}, P, 2'b0});
assign T[3*`NF+6:2*`NF+4] = A[3*`NF+6:2*`NF+4]; assign T[3*`NF+6:2*`NF+4] = A[3*`NF+6:2*`NF+4];
assign Z[3*`NF+5:2*`NF+4] = A[3*`NF+5:2*`NF+4]; assign Z[3*`NF+5:2*`NF+4] = A[3*`NF+5:2*`NF+4];
assign T[2*`NF+3:2] = A[2*`NF+3:2]^P; assign T[2*`NF+3:2] = A[2*`NF+3:2]^P;
@ -739,7 +474,6 @@ module poslza(
// Apply function to determine Leading pattern // Apply function to determine Leading pattern
logic [3*`NF+6:0] pf; logic [3*`NF+6:0] pf;
assign pf = T^{Z[3*`NF+5:0], 1'b0}; assign pf = T^{Z[3*`NF+5:0], 1'b0};
// assign pf = T^{~Z[3*`NF+5:0], 1'b0};
logic [8:0] i; logic [8:0] i;
always_comb begin always_comb begin
@ -751,16 +485,12 @@ module poslza(
endmodule endmodule
module neglza( module neglza(
// parameter SIGNIFICANT_SZ=52; input logic [3*`NF+6:0] A, // addend
//leading digit anticipator input logic [3*`NF+6:0] P, // product
// localparam sz=SIGNIFICANT_SZ+1; output logic [8:0] NCnt // normalization shift count for the negitive result
input logic [3*`NF+6:0] A,
input logic [3*`NF+6:0] P,
output logic [8:0] NCnt
); );
// Compute Generate, Propageate and Kill for each bit // calculate the propagate (T) and kill (Z) bits
logic [3*`NF+6:0] T; logic [3*`NF+6:0] T;
logic [3*`NF+5:0] Z; logic [3*`NF+5:0] Z;
assign T = A^P; assign T = A^P;
@ -783,28 +513,27 @@ endmodule
module normalize( module normalize(
input logic [3*`NF+5:0] SumM, input logic [3*`NF+5:0] SumM, // the positive sum
input logic [`NE-1:0] ZExpM, input logic [`NE-1:0] ZExpM, // exponent of Z
input logic [`NE+1:0] ProdExpM, // X exponent + Y exponent - bias input logic [`NE+1:0] ProdExpM, // X exponent + Y exponent - bias
input logic [8:0] NormCntM, input logic [8:0] NormCntM, // normalization shift count
input logic FmtM, // precision 1 = double 0 = single input logic FmtM, // precision 1 = double 0 = single
input logic KillProdM, input logic KillProdM, // is the product set to zero
input logic AddendStickyM, input logic AddendStickyM, // the sticky bit caclulated from the aligned addend
output logic [`NF+2:0] NormSum, // normalized sum output logic [`NF+2:0] NormSum, // normalized sum
output logic SumZero, output logic SumZero, // is the sum zero
output logic NormSumSticky, UfSticky, output logic NormSumSticky, UfSticky, // sticky bits
output logic [`NE+1:0] SumExp, // exponent of the normalized sum output logic [`NE+1:0] SumExp, // exponent of the normalized sum
output logic ResultDenorm output logic ResultDenorm // is the result denormalized
); );
logic [`NE+1:0] FracLen; // length of the fraction logic [`NE+1:0] FracLen; // length of the fraction
logic [`NE+1:0] SumExpTmp; // exponent of the normalized sum not taking into account denormal or zero results logic [`NE+1:0] SumExpTmp; // exponent of the normalized sum not taking into account denormal or zero results
logic [`NE+1:0] SumExpTmpMinus1; // SumExpTmp-1
logic [8:0] DenormShift; // right shift if the result is denormalized //***change this later logic [8:0] DenormShift; // right shift if the result is denormalized //***change this later
logic [3*`NF+5:0] SumShifted; // sum shifted for normalization logic [3*`NF+5:0] CorrSumShifted; // the shifted sum after LZA correction
logic [3*`NF+7:0] SumShiftedTmp; // sum shifted for normalization logic [3*`NF+7:0] SumShifted; // the shifted sum before LZA correction
logic [`NE+1:0] SumExpTmpTmp; logic [`NE+1:0] SumExpTmpTmp; // the exponent of the normalized sum with the `FLEN bias
logic PreResultDenorm; logic PreResultDenorm; // is the result denormalized - calculated before LZA corection
logic LZAPlus1; logic LZAPlus1; // add one to the sum's exponent due to LZA correction
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Normalization // Normalization
@ -815,87 +544,58 @@ module normalize(
// determine the length of the fraction based on precision // determine the length of the fraction based on precision
assign FracLen = FmtM ? `NF+1 : 13'd24; assign FracLen = FmtM ? `NF+1 : 13'd24;
//assign FracLen = `NF;
// Determine if the result is denormal // calculate the sum's exponent
assign SumExpTmpTmp = KillProdM ? {2'b0, ZExpM} : ProdExpM + -({4'b0, NormCntM} + 1 - (`NF+4)); assign SumExpTmpTmp = KillProdM ? {2'b0, ZExpM} : ProdExpM + -({4'b0, NormCntM} + 1 - (`NF+4));
assign SumExpTmp = FmtM ? SumExpTmpTmp : (SumExpTmpTmp-1023+127)&{`NE+2{|SumExpTmpTmp}}; assign SumExpTmp = FmtM ? SumExpTmpTmp : (SumExpTmpTmp-1023+127)&{`NE+2{|SumExpTmpTmp}};
// Determine if the result is denormal
assign PreResultDenorm = $signed(SumExpTmp)<=0 & ($signed(SumExpTmp)>=$signed(-FracLen)) & ~SumZero; assign PreResultDenorm = $signed(SumExpTmp)<=0 & ($signed(SumExpTmp)>=$signed(-FracLen)) & ~SumZero;
// Determine the shift needed for denormal results // Determine the shift needed for denormal results
// - if not denorm add 1 to shift out the leading 1 // - if not denorm add 1 to shift out the leading 1
assign DenormShift = PreResultDenorm ? SumExpTmp[8:0] : 1; //*** change this when changing the size of DenormShift also change to an and opperation assign DenormShift = PreResultDenorm ? SumExpTmp[8:0] : 1; //*** change this when changing the size of DenormShift also change to an and opperation
// Normalize the sum // Normalize the sum
assign SumShiftedTmp = {2'b0, SumM} << NormCntM+DenormShift; //*** fix mux's with constants in them //***NormCnt can be simplified assign SumShifted = {2'b0, SumM} << NormCntM+DenormShift; //*** fix mux's with constants in them //***NormCnt can be simplified
// LZA correction // LZA correction
assign LZAPlus1 = SumShiftedTmp[3*`NF+7]; assign LZAPlus1 = SumShifted[3*`NF+7];
assign SumShifted = LZAPlus1 ? SumShiftedTmp[3*`NF+6:1] : SumShiftedTmp[3*`NF+5:0]; assign CorrSumShifted = LZAPlus1 ? SumShifted[3*`NF+6:1] : SumShifted[3*`NF+5:0];
assign NormSum = SumShifted[3*`NF+5:2*`NF+3]; assign NormSum = CorrSumShifted[3*`NF+5:2*`NF+3];
// Calculate the sticky bit // Calculate the sticky bit
assign NormSumSticky = (|SumShifted[2*`NF+2:0]) | (|SumShifted[136:2*`NF+3]&~FmtM); assign NormSumSticky = (|CorrSumShifted[2*`NF+2:0]) | (|CorrSumShifted[136:2*`NF+3]&~FmtM);
assign UfSticky = AddendStickyM | NormSumSticky; assign UfSticky = AddendStickyM | NormSumSticky;
// Determine sum's exponent // Determine sum's exponent
assign SumExp = (SumExpTmp+LZAPlus1+(~|SumExpTmp&SumShiftedTmp[3*`NF+6])) & {`NE+2{~(SumZero|ResultDenorm)}}; assign SumExp = (SumExpTmp+LZAPlus1+(~|SumExpTmp&SumShifted[3*`NF+6])) & {`NE+2{~(SumZero|ResultDenorm)}};
// recalculate if the result is denormalized // recalculate if the result is denormalized
assign ResultDenorm = PreResultDenorm&~SumShiftedTmp[3*`NF+6]&~SumShiftedTmp[3*`NF+7]; assign ResultDenorm = PreResultDenorm&~SumShifted[3*`NF+6]&~SumShifted[3*`NF+7];
// // Determine if the sum is zero
// assign SumZero = ~(|Sum);
// // determine the length of the fraction based on precision
// assign FracLen = FmtM ? `NF : 13'd23;
// //assign FracLen = `NF;
// // Determine if the result is denormal
// assign SumExpTmpTmp = KillProdM ? {2'b0, ZExpM} : ProdExpM + -({4'b0, NormCnt} + 1 - (`NF+4));
// assign SumExpTmp = FmtM ? SumExpTmpTmp : (SumExpTmpTmp-1023+127)&{`NE+2{|SumExpTmpTmp}};
// assign ResultDenorm = $signed(SumExpTmp)<=0 & ($signed(SumExpTmp)>=$signed(-FracLen)) & ~SumZero;
// // Determine the shift needed for denormal results
// // - if not denorm add 1 to shift out the leading 1
// assign DenormShift = ResultDenorm ? SumExpTmp[8:0] : 1; //*** change this when changing the size of DenormShift also change to an and opperation
// // Normalize the sum
// assign SumShifted = SumZero ? 0 : Sum << NormCnt+DenormShift; //*** fix mux's with constants in them
// assign NormSum = SumShifted[3*`NF+5:2*`NF+3];
// // Calculate the sticky bit
// assign NormSumSticky = FmtM ? (|SumShifted[2*`NF+2:0]) : (|SumShifted[136:0]);
// assign UfSticky = AddendStickyM | NormSumSticky;
// // Determine sum's exponent
// assign SumExp = SumZero ? 0 : //***again fix mux
// ResultDenorm ? 0 :
// SumExpTmp;
endmodule endmodule
module fmaround( module fmaround(
input logic FmtM, // precision 1 = double 0 = single input logic FmtM, // precision 1 = double 0 = single
input logic [2:0] FrmM, input logic [2:0] FrmM, // rounding mode
input logic UfSticky, input logic UfSticky, // sticky bit for underlow calculation
output logic Sticky,
input logic [`NF+2:0] NormSum, // normalized sum input logic [`NF+2:0] NormSum, // normalized sum
input logic AddendStickyM, input logic AddendStickyM, // addend's sticky bit
input logic NormSumSticky, input logic NormSumSticky, // normalized sum's sticky bit
input logic ZZeroM, input logic ZZeroM, // is Z zero
input logic InvZM, input logic InvZM, // invert Z
input logic [`NE+1:0] SumExp, // exponent of the normalized sum input logic [`NE+1:0] SumExp, // exponent of the normalized sum
input logic ResultSgn, input logic ResultSgn, // the result's sign
output logic CalcPlus1, Plus1, UfPlus1, Minus1, output logic CalcPlus1, Plus1, UfPlus1, Minus1, // do you add or subtract on from the result
output logic [`NE+1:0] FullResultExp, // ResultExp with bits to determine sign and overflow output logic [`NE+1:0] FullResultExp, // ResultExp with bits to determine sign and overflow
output logic [`NF-1:0] ResultFrac, // Result fraction output logic [`NF-1:0] ResultFrac, // Result fraction
output logic [`NE-1:0] ResultExp, // Result exponent output logic [`NE-1:0] ResultExp, // Result exponent
output logic Round, Guard, UfRound, UfLSBNormSum output logic Sticky, // sticky bit
output logic Round, Guard, UfRound, UfLSBNormSum // bits needed to calculate rounding
); );
logic LSBNormSum; logic LSBNormSum; // bit used for rounding - least significant bit of the normalized sum
logic SubBySmallNum, UfSubBySmallNum; // was there supposed to be a subtraction by a small number logic SubBySmallNum, UfSubBySmallNum; // was there supposed to be a subtraction by a small number
logic UfGuard; logic UfGuard; // gaurd bit used to caluculate underflow
logic UfCalcPlus1, CalcMinus1; logic UfCalcPlus1, CalcMinus1; // do you add or subtract on from the result
logic [`FLEN:0] RoundAdd; //*** move this up logic [`FLEN:0] RoundAdd; // how much to add to the result
logic [`NF-1:0] NormSumTruncated; logic [`NF-1:0] NormSumTruncated; // the normalized sum trimed to fit the mantissa
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Rounding // Rounding
@ -997,15 +697,15 @@ module fmaflags(
input logic XNaNM, YNaNM, ZNaNM, // inputs are NaN input logic XNaNM, YNaNM, ZNaNM, // inputs are NaN
input logic [`NE+1:0] FullResultExp, // ResultExp with bits to determine sign and overflow input logic [`NE+1:0] FullResultExp, // ResultExp with bits to determine sign and overflow
input logic [`NE+1:0] SumExp, // exponent of the normalized sum input logic [`NE+1:0] SumExp, // exponent of the normalized sum
input logic ZSgnEffM, PSgnM, input logic ZSgnEffM, PSgnM, // the product and modified Z signs
input logic Round, Guard, UfRound, UfLSBNormSum, Sticky, UfPlus1, input logic Round, Guard, UfRound, UfLSBNormSum, Sticky, UfPlus1, // bits used to determine rounding
input logic FmtM, // precision 1 = double 0 = single input logic FmtM, // precision 1 = double 0 = single
output logic Invalid, Overflow, Underflow, output logic Invalid, Overflow, Underflow, // flags used to select the result
output logic [4:0] FMAFlgM output logic [4:0] FMAFlgM // FMA flags
); );
logic [`NE+1:0] MaxExp; // maximum value of the exponent logic [`NE+1:0] MaxExp; // maximum value of the exponent
logic SigNaN; logic SigNaN; // is an input a signaling NaN
logic UnderflowFlag, Inexact; logic UnderflowFlag, Inexact; // flags
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Flags // Flags

16
wally-pipelined/src/fpu/fpu.sv
View File

@ -225,7 +225,7 @@ module fpu (
.XSgnM, .YSgnM, .XExpM, .YExpM, .ZExpM, .XManM, .YManM, .ZManM, .XSgnM, .YSgnM, .XExpM, .YExpM, .ZExpM, .XManM, .YManM, .ZManM,
.XNaNM, .YNaNM, .ZNaNM, .XZeroM, .YZeroM, .ZZeroM, .XNaNM, .YNaNM, .ZNaNM, .XZeroM, .YZeroM, .ZZeroM,
.XInfM, .YInfM, .ZInfM, .XSNaNM, .YSNaNM, .ZSNaNM, .XInfM, .YInfM, .ZInfM, .XSNaNM, .YSNaNM, .ZSNaNM,
.FOpCtrlE, .FOpCtrlM, .FOpCtrlE,
.FmtE, .FmtM, .FrmM, .FmtE, .FmtM, .FrmM,
// outputs: // outputs:
.FMAFlgM, .FMAResM); .FMAFlgM, .FMAResM);
@ -257,19 +257,7 @@ module fpu (
// outputs: // outputs:
.FDivBusyE, .done(FDivSqrtDoneE), .AS_Result(FDivResM), .Flags(FDivFlgM)); .FDivBusyE, .done(FDivSqrtDoneE), .AS_Result(FDivResM), .Flags(FDivFlgM));
// convert from signle to double and vice versa
// add/FP <-> FP convert
// - computation is done in two stages
// - contains some E/M pipleine registers
//*** remove uneeded logic
//*** change to use the unpacking unit if possible
// faddcvt faddcvt (.clk, .reset, .FlushM, .StallM, .FrmM, .FOpCtrlM, .FmtE, .FmtM, .FSrcXE, .FSrcYE, .FOpCtrlE,
// .XSgnM, .YSgnM, .XManM, .YManM, .XExpM, .YExpM,
// .XSgnE, .YSgnE, .XManE, .YManE, .XExpE, .YExpE, .XDenormE, .YDenormE, .XNormE, .XNormM, .YNormM, .XZeroE, .YZeroE, .XInfE, .YInfE, .XNaNE, .YNaNE, .XSNaNE, .YSNaNE,
// // outputs:
// .CvtFpResM, .CvtFpFlgM);
cvtfp cvtfp (.XExpE, .XManE, .XSgnE, .XZeroE, .XDenormE, .XInfE, .XNaNE, .XSNaNE, .FrmE, .FmtE, .CvtFpResE, .CvtFpFlgE); cvtfp cvtfp (.XExpE, .XManE, .XSgnE, .XZeroE, .XDenormE, .XInfE, .XNaNE, .XSNaNE, .FrmE, .FmtE, .CvtFpResE, .CvtFpFlgE);
// compare unit // compare unit