forked from Github_Repos/cvw
583 lines
27 KiB
Systemverilog
583 lines
27 KiB
Systemverilog
module fma(
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input logic clk,
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input logic reset,
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input logic FlushM,
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input logic StallM,
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input logic [63:0] SrcXE, SrcXM, // X
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input logic [63:0] SrcYE, SrcYM, // Y
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input logic [63:0] SrcZE, SrcZM, // Z
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input logic FmtE, FmtM, // precision 1 = double 0 = single
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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)
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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
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output logic [63:0] FMAResM,
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output logic [4:0] FMAFlgM);
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logic [105:0] ProdManE, ProdManM;
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logic [161:0] AlignedAddendE, AlignedAddendM;
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logic [12:0] ProdExpE, ProdExpM;
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logic AddendStickyE, AddendStickyM;
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logic KillProdE, KillProdM;
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logic XZeroE, YZeroE, ZZeroE, XZeroM, YZeroM, ZZeroM;
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logic XInfE, YInfE, ZInfE, XInfM, YInfM, ZInfM;
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logic XNaNE, YNaNE, ZNaNE, XNaNM, YNaNM, ZNaNM;
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fma1 fma1 (.X(SrcXE), .Y(SrcYE), .Z(SrcZE), .FOpCtrlE, .FmtE, .ProdManE, .AlignedAddendE,
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.ProdExpE, .AddendStickyE, .KillProdE, .XZeroE, .YZeroE, .ZZeroE, .XInfE, .YInfE, .ZInfE,
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.XNaNE, .YNaNE, .ZNaNE );
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flopenrc #(106) EMRegFma1(clk, reset, FlushM, ~StallM, ProdManE, ProdManM);
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flopenrc #(162) EMRegFma2(clk, reset, FlushM, ~StallM, AlignedAddendE, AlignedAddendM);
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flopenrc #(13) EMRegFma3(clk, reset, FlushM, ~StallM, ProdExpE, ProdExpM);
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flopenrc #(11) EMRegFma4(clk, reset, FlushM, ~StallM,
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{AddendStickyE, KillProdE, XZeroE, YZeroE, ZZeroE, XInfE, YInfE, ZInfE, XNaNE, YNaNE, ZNaNE},
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{AddendStickyM, KillProdM, XZeroM, YZeroM, ZZeroM, XInfM, YInfM, ZInfM, XNaNM, YNaNM, ZNaNM});
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fma2 fma2(.X(SrcXM), .Y(SrcYM), .Z(SrcZM), .FOpCtrlM, .FrmM, .FmtM,
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.ProdManM, .AlignedAddendM, .ProdExpM, .AddendStickyM, .KillProdM,
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.XZeroM, .YZeroM, .ZZeroM, .XInfM, .YInfM, .ZInfM, .XNaNM, .YNaNM, .ZNaNM,
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.FMAResM, .FMAFlgM);
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endmodule
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module fma1(
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input logic [63:0] X, // X
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input logic [63:0] Y, // Y
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input logic [63:0] Z, // Z
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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)
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input logic FmtE, // precision 1 = double 0 = single
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output logic [105:0] ProdManE, // 1.X frac * 1.Y frac
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output logic [161:0] AlignedAddendE, // Z aligned for addition
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output logic [12:0] ProdExpE, // X exponent + Y exponent - bias
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output logic AddendStickyE, // sticky bit that is calculated during alignment
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output logic KillProdE, // set the product to zero before addition if the product is too small to matter
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output logic XZeroE, YZeroE, ZZeroE, // inputs are zero
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output logic XInfE, YInfE, ZInfE, // inputs are infinity
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output logic XNaNE, YNaNE, ZNaNE); // inputs are NaN
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logic [51:0] XFrac,YFrac,ZFrac; // input fraction
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logic [52:0] XMan,YMan,ZMan; // input mantissa (with leading one)
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logic [12:0] XExp,YExp,ZExp; // input exponents
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logic XSgn,YSgn,ZSgn; // input signs
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logic [12:0] AlignCnt; // how far to shift the addend to align with the product
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logic [213:0] ZManShifted; // output of the alignment shifter including sticky bit
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logic [213:0] ZManPreShifted; // input to the alignment shifter
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logic XDenorm, YDenorm, ZDenorm; // inputs are denormal
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logic [63:0] Addend; // value to add (Z or zero)
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logic [12:0] Bias; // 1023 for double, 127 for single
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logic XExpZero, YExpZero, ZExpZero; // input exponent zero
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logic XFracZero, YFracZero, ZFracZero; // input fraction zero
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logic XExpMax, YExpMax, ZExpMax; // input exponent all 1s
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///////////////////////////////////////////////////////////////////////////////
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// split inputs into the sign bit, fraction, and exponent to handle single or double precision
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// - single precision is in the top half of the inputs
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///////////////////////////////////////////////////////////////////////////////
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// Set addend to zero if FMUL instruction
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assign Addend = FOpCtrlE[2] ? 64'b0 : Z;
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assign XSgn = X[63];
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assign YSgn = Y[63];
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assign ZSgn = Addend[63];
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assign XExp = FmtE ? {2'b0, X[62:52]} : {5'b0, X[62:55]};
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assign YExp = FmtE ? {2'b0, Y[62:52]} : {5'b0, Y[62:55]};
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assign ZExp = FmtE ? {2'b0, Addend[62:52]} : {5'b0, Addend[62:55]};
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assign XFrac = FmtE ? X[51:0] : {X[54:32], 29'b0};
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assign YFrac = FmtE ? Y[51:0] : {Y[54:32], 29'b0};
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assign ZFrac = FmtE ? Addend[51:0] : {Addend[54:32], 29'b0};
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assign XMan = {~XExpZero, XFrac};
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assign YMan = {~YExpZero, YFrac};
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assign ZMan = {~ZExpZero, ZFrac};
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assign Bias = FmtE ? 13'h3ff : 13'h7f;
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///////////////////////////////////////////////////////////////////////////////
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// determine if an input is a special value
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///////////////////////////////////////////////////////////////////////////////
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assign XExpZero = ~|XExp;
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assign YExpZero = ~|YExp;
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assign ZExpZero = ~|ZExp;
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assign XFracZero = ~|XFrac;
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assign YFracZero = ~|YFrac;
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assign ZFracZero = ~|ZFrac;
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assign XExpMax = FmtE ? &XExp[10:0] : &XExp[7:0];
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assign YExpMax = FmtE ? &YExp[10:0] : &YExp[7:0];
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assign ZExpMax = FmtE ? &ZExp[10:0] : &ZExp[7:0];
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assign XNaNE = XExpMax & ~XFracZero;
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assign YNaNE = YExpMax & ~YFracZero;
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assign ZNaNE = ZExpMax & ~ZFracZero;
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assign XDenorm = XExpZero & ~XFracZero;
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assign YDenorm = YExpZero & ~YFracZero;
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assign ZDenorm = ZExpZero & ~ZFracZero;
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assign XInfE = XExpMax & XFracZero;
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assign YInfE = YExpMax & YFracZero;
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assign ZInfE = ZExpMax & ZFracZero;
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assign XZeroE = XExpZero & XFracZero;
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assign YZeroE = YExpZero & YFracZero;
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assign ZZeroE = ZExpZero & ZFracZero;
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///////////////////////////////////////////////////////////////////////////////
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// Calculate the product
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// - When multipliying two fp numbers, add the exponents
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// - Subtract the bias (XExp + YExp has two biases, one from each exponent)
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// - Denormal numbers have an an exponent value of 1, however they are
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// represented with an exponent of 0. add one if there is a denormal number
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///////////////////////////////////////////////////////////////////////////////
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// verilator lint_off WIDTH
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assign ProdExpE = (XZeroE|YZeroE) ? 13'b0 :
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XExp + YExp - Bias + XDenorm + YDenorm;
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// Calculate the product's mantissa
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// - Add the assumed one. If the number is denormalized or zero, it does not have an assumed one.
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assign ProdManE = XMan * YMan;
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///////////////////////////////////////////////////////////////////////////////
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// Alignment shifter
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///////////////////////////////////////////////////////////////////////////////
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// determine the shift count for alignment
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// - negitive means Z is larger, so shift Z left
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// - positive means the product is larger, so shift Z right
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// - Denormal numbers have an an exponent value of 1, however they are
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// represented with an exponent of 0. add one to the exponent if it is a denormal number
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assign AlignCnt = ProdExpE - ZExp - ZDenorm;
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// verilator lint_on WIDTH
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// Defualt Addition without shifting
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// | 55'b0 | 106'b(product) | 2'b0 |
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// |1'b0| addnend |
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// the 1'b0 before the added is because the product's mantissa has two bits before the binary point (xx.xxxxxxxxxx...)
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assign ZManPreShifted = {55'b0, ZMan, 106'b0};
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always_comb
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begin
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// If the product is too small to effect the sum, kill the product
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// | 54'b0 | 106'b(product) | 2'b0 |
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// | addnend |
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if ($signed(AlignCnt) <= $signed(-13'd56)) begin
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KillProdE = 1;
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ZManShifted = ZManPreShifted;//{107'b0, ZMan, 54'b0};
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AddendStickyE = ~(XZeroE|YZeroE);
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// If the Addend is shifted left (negitive AlignCnt)
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// | 54'b0 | 106'b(product) | 2'b0 |
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// | addnend |
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end else if($signed(AlignCnt) <= $signed(13'd0)) begin
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KillProdE = 0;
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ZManShifted = ZManPreShifted << -AlignCnt;
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AddendStickyE = |(ZManShifted[51:0]);
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// If the Addend is shifted right (positive AlignCnt)
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// | 54'b0 | 106'b(product) | 2'b0 |
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// | addnend |
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end else if ($signed(AlignCnt)<=$signed(13'd106)) begin
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KillProdE = 0;
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ZManShifted = ZManPreShifted >> AlignCnt;
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AddendStickyE = |(ZManShifted[51:0]);
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// If the addend is too small to effect the addition
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// - The addend has to shift two past the end of the addend to be considered too small
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// - The 2 extra bits are needed for rounding
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// | 54'b0 | 106'b(product) | 2'b0 |
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// | addnend |
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end else begin
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KillProdE = 0;
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ZManShifted = 0;
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AddendStickyE = ~ZZeroE;
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end
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end
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assign AlignedAddendE = ZManShifted[213:52];
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endmodule
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module fma2(
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input logic [63:0] X, // X
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input logic [63:0] Y, // Y
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input logic [63:0] Z, // Z
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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
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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)
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input logic FmtM, // precision 1 = double 0 = single
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input logic [105:0] ProdManM, // 1.X frac * 1.Y frac
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input logic [161:0] AlignedAddendM, // Z aligned for addition
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input logic [12:0] ProdExpM, // X exponent + Y exponent - bias
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input logic AddendStickyM, // sticky bit that is calculated during alignment
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input logic KillProdM, // set the product to zero before addition if the product is too small to matter
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input logic XZeroM, YZeroM, ZZeroM, // inputs are zero
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input logic XInfM, YInfM, ZInfM, // inputs are infinity
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input logic XNaNM, YNaNM, ZNaNM, // inputs are NaN
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output logic [63:0] FMAResM, // FMA final result
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output logic [4:0] FMAFlgM); // FMA flags {invalid, divide by zero, overflow, underflow, inexact}
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logic [51:0] ResultFrac; // Result fraction
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logic [10:0] ResultExp; // Result exponent
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logic ResultSgn; // Result sign
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logic [10:0] ZExp; // input exponent
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logic XSgn, YSgn, ZSgn; // input sign
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logic PSgn; // product sign
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logic [105:0] ProdMan2; // product being added
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logic [162:0] AlignedAddend2; // possibly inverted aligned Z
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logic [161:0] Sum; // positive sum
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logic [162:0] PreSum; // possibly negitive sum
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logic [12:0] SumExp; // exponent of the normalized sum
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logic [12:0] SumExpTmp; // exponent of the normalized sum not taking into account denormal or zero results
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logic [12:0] SumExpTmpMinus1; // SumExpTmp-1
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logic [12:0] FullResultExp; // ResultExp with bits to determine sign and overflow
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logic [54:0] NormSum; // normalized sum
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logic [161:0] SumShifted; // sum shifted for normalization
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logic [8:0] NormCnt; // output of the leading zero detector
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logic NormSumSticky; // sticky bit calulated from the normalized sum
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logic SumZero; // is the sum zero
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logic NegSum; // is the sum negitive
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logic InvZ; // invert Z if there is a subtraction (-product + Z or product - Z)
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logic ResultDenorm; // is the result denormalized
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logic Sticky; // Sticky bit
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logic Plus1, Minus1, CalcPlus1, CalcMinus1; // do you add or subtract one for rounding
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logic UfPlus1, UfCalcPlus1; // do you add one (for determining underflow flag)
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logic Invalid,Underflow,Overflow,Inexact; // flags
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logic [8:0] DenormShift; // right shift if the result is denormalized
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logic SubBySmallNum; // was there supposed to be a subtraction by a small number
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logic [63:0] Addend; // value to add (Z or zero)
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logic ZeroSgn; // the result's sign if the sum is zero
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logic ResultSgnTmp; // the result's sign assuming the result is not zero
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logic Guard, Round, LSBNormSum; // bits needed to determine rounding
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logic UfGuard, UfRound, UfLSBNormSum; // bits needed to determine rounding for underflow flag
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logic [12:0] MaxExp; // maximum value of the exponent
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logic [12:0] FracLen; // length of the fraction
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logic SigNaN; // is an input a signaling NaN
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logic UnderflowFlag; // Underflow singal used in FMAFlgM (used to avoid a circular depencency)
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logic [63:0] XNaNResult, YNaNResult, ZNaNResult, InvalidResult, OverflowResult, KillProdResult, UnderflowResult; // possible results
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///////////////////////////////////////////////////////////////////////////////
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// Select input fields
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// The following logic duplicates fma1 because it's cheaper to recompute than provide registers
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///////////////////////////////////////////////////////////////////////////////
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// Set addend to zero if FMUL instruction
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assign Addend = FOpCtrlM[2] ? 64'b0 : Z;
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// split inputs into the sign bit, and exponent to handle single or double precision
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// - single precision is in the top half of the inputs
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assign XSgn = X[63];
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assign YSgn = Y[63];
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assign ZSgn = Addend[63]^FOpCtrlM[0]; //Negate Z if subtraction
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assign ZExp = FmtM ? Addend[62:52] : {3'b0, Addend[62:55]};
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// Calculate the product's sign
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// Negate product's sign if FNMADD or FNMSUB
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assign PSgn = XSgn ^ YSgn ^ FOpCtrlM[1];
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///////////////////////////////////////////////////////////////////////////////
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// Addition
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///////////////////////////////////////////////////////////////////////////////
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// Negate Z when doing one of the following opperations:
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// -prod + Z
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// prod - Z
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assign InvZ = ZSgn ^ PSgn;
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// Choose an inverted or non-inverted addend - the one is added later
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assign AlignedAddend2 = InvZ ? ~{1'b0, AlignedAddendM} : {1'b0, AlignedAddendM};
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// Kill the product if the product is too small to effect the addition (determined in fma1.sv)
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assign ProdMan2 = KillProdM ? 106'b0 : ProdManM;
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// Do the addition
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// - add one to negate if the added was inverted
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// - the 2 extra bits at the begining and end are needed for rounding
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assign PreSum = AlignedAddend2 + {55'b0, ProdMan2, 2'b0} + {162'b0, InvZ};
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// Is the sum negitive
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assign NegSum = PreSum[162];
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// If the sum is negitive, negate the sum.
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assign Sum = NegSum ? -PreSum[161:0] : PreSum[161:0];
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///////////////////////////////////////////////////////////////////////////////
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// Leading one detector
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///////////////////////////////////////////////////////////////////////////////
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//*** replace with non-behavoral code
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logic [8:0] i;
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always_comb begin
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i = 0;
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while (~Sum[161-i] && $unsigned(i) <= $unsigned(9'd161)) i = i+1; // search for leading one
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NormCnt = i+1; // compute shift count
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end
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///////////////////////////////////////////////////////////////////////////////
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// Normalization
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///////////////////////////////////////////////////////////////////////////////
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// Determine if the sum is zero
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assign SumZero = ~(|Sum);
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// determine the length of the fraction based on precision
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assign FracLen = FmtM ? 13'd52 : 13'd23;
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// Determine if the result is denormal
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assign SumExpTmp = KillProdM ? {2'b0, ZExp} : ProdExpM + -({4'b0, NormCnt} - 13'd56);
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assign ResultDenorm = $signed(SumExpTmp)<=0 & ($signed(SumExpTmp)>=$signed(-FracLen)) & ~SumZero;
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// Determine the shift needed for denormal results
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assign SumExpTmpMinus1 = SumExpTmp-1;
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assign DenormShift = ResultDenorm ? SumExpTmpMinus1[8:0] : 9'b0;
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// Normalize the sum
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assign SumShifted = SumZero ? 162'b0 : Sum << NormCnt+DenormShift;
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assign NormSum = SumShifted[161:107];
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// Calculate the sticky bit
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assign NormSumSticky = FmtM ? (|SumShifted[107:0]) : (|SumShifted[136:0]);
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assign Sticky = AddendStickyM | NormSumSticky;
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// Determine sum's exponent
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assign SumExp = SumZero ? 13'b0 :
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ResultDenorm ? 13'b0 :
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SumExpTmp;
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///////////////////////////////////////////////////////////////////////////////
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// Rounding
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///////////////////////////////////////////////////////////////////////////////
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// round to nearest even
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// {Guard, Round, Sticky}
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// 0xx - do nothing
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// 100 - tie - Plus1 if result is odd (LSBNormSum = 1)
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// - don't add 1 if a small number was supposed to be subtracted
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// 101 - do nothing if a small number was supposed to subtracted (the sticky bit was set by the small number)
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// 110/111 - Plus1
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// 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
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// round to -infinity
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// - Plus1 if negative unless a small number was supposed to be subtracted from a result with guard and round bits of 0
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// - subtract 1 if a small number was supposed to be subtracted from a positive result with guard and round bits of 0
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// round to infinity
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// - Plus1 if positive unless a small number was supposed to be subtracted from a result with guard and round bits of 0
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// - subtract 1 if a small number was supposed to be subtracted from a negative result with guard and round bits of 0
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// round to nearest max magnitude
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// {Guard, Round, Sticky}
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// 0xx - do nothing
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// 100 - tie - Plus1
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// - don't add 1 if a small number was supposed to be subtracted
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// 101 - do nothing if a small number was supposed to subtracted (the sticky bit was set by the small number)
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// 110/111 - Plus1
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// determine guard, round, and least significant bit of the result
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assign Guard = FmtM ? NormSum[2] : NormSum[31];
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assign Round = FmtM ? NormSum[1] : NormSum[30];
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assign LSBNormSum = FmtM ? NormSum[3] : NormSum[32];
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// used to determine underflow flag
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assign UfGuard = FmtM ? NormSum[1] : NormSum[30];
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assign UfRound = FmtM ? NormSum[0] : NormSum[29];
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assign UfLSBNormSum = FmtM ? NormSum[2] : NormSum[31];
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// Deterimine if a small number was supposed to be subtrated
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assign SubBySmallNum = AddendStickyM&InvZ&~(NormSumSticky)&~ZZeroM;
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always_comb begin
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// Determine if you add 1
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case (FrmM)
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3'b000: CalcPlus1 = Guard & (Round | ((Sticky|UfGuard)&~(~Round&SubBySmallNum)) | (~Round&~(Sticky|UfGuard)&LSBNormSum&~SubBySmallNum));//round to nearest even
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3'b001: CalcPlus1 = 0;//round to zero
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3'b010: CalcPlus1 = ResultSgn & ~(SubBySmallNum & ~Guard & ~Round);//round down
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3'b011: CalcPlus1 = ~ResultSgn & ~(SubBySmallNum & ~Guard & ~Round);//round up
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3'b100: CalcPlus1 = (Guard & (Round | ((Sticky|UfGuard)&~(~Round&SubBySmallNum)) | (~Round&~(Sticky|UfGuard)&~SubBySmallNum)));//round to nearest max magnitude
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default: CalcPlus1 = 1'bx;
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endcase
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// Determine if you add 1 (for underflow flag)
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case (FrmM)
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3'b000: UfCalcPlus1 = UfGuard & (UfRound | (Sticky&~(~UfRound&SubBySmallNum)) | (~UfRound&~Sticky&UfLSBNormSum&~SubBySmallNum));//round to nearest even
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3'b001: UfCalcPlus1 = 0;//round to zero
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3'b010: UfCalcPlus1 = ResultSgn & ~(SubBySmallNum & ~UfGuard & ~UfRound);//round down
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3'b011: UfCalcPlus1 = ~ResultSgn & ~(SubBySmallNum & ~UfGuard & ~UfRound);//round up
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3'b100: UfCalcPlus1 = (UfGuard & (UfRound | (Sticky&~(~UfRound&SubBySmallNum)) | (~UfRound&~Sticky&~SubBySmallNum)));//round to nearest max magnitude
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default: UfCalcPlus1 = 1'bx;
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endcase
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// Determine if you subtract 1
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case (FrmM)
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3'b000: CalcMinus1 = 0;//round to nearest even
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3'b001: CalcMinus1 = SubBySmallNum & ~Guard & ~Round;//round to zero
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3'b010: CalcMinus1 = ~ResultSgn & ~Guard & ~Round & SubBySmallNum;//round down
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3'b011: CalcMinus1 = ResultSgn & ~Guard & ~Round & SubBySmallNum;//round up
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3'b100: CalcMinus1 = 0;//round to nearest max magnitude
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default: CalcMinus1 = 1'bx;
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endcase
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end
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// If an answer is exact don't round
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assign Plus1 = CalcPlus1 & (Sticky | UfGuard | Guard | Round);
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assign UfPlus1 = UfCalcPlus1 & (Sticky | UfGuard | UfRound);
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assign Minus1 = CalcMinus1 & (Sticky | UfGuard | Guard | Round);
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// Compute rounded result
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logic [64:0] RoundAdd;
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logic [51:0] NormSumTruncated;
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assign RoundAdd = FmtM ? Minus1 ? {65{1'b1}} : {64'b0, Plus1} :
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Minus1 ? {{36{1'b1}}, 29'b0} : {35'b0, Plus1, 29'b0};
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assign NormSumTruncated = FmtM ? NormSum[54:3] : {NormSum[54:32], 29'b0};
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assign {FullResultExp, ResultFrac} = {SumExp, NormSumTruncated} + RoundAdd;
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assign ResultExp = FullResultExp[10:0];
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///////////////////////////////////////////////////////////////////////////////
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// Sign calculation
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///////////////////////////////////////////////////////////////////////////////
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// Determine the sign if the sum is zero
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// if cancelation then 0 unless round to -infinity
|
|
// otherwise psign
|
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assign ZeroSgn = (PSgn^ZSgn)&~Underflow ? FrmM == 3'b010 : PSgn;
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// is the result negitive
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// if p - z is the Sum negitive
|
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// if -p + z is the Sum positive
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// if -p - z then the Sum is negitive
|
|
assign ResultSgnTmp = InvZ&(ZSgn)&NegSum | InvZ&PSgn&~NegSum | ((ZSgn)&PSgn);
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|
assign ResultSgn = SumZero ? ZeroSgn : ResultSgnTmp;
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///////////////////////////////////////////////////////////////////////////////
|
|
// Flags
|
|
///////////////////////////////////////////////////////////////////////////////
|
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|
// 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 ? 13'd2047 : 13'd255;
|
|
assign SigNaN = FmtM ? (XNaNM&~X[51]) | (YNaNM&~Y[51]) | (ZNaNM&~Addend[51]) :
|
|
(XNaNM&~X[54]) | (YNaNM&~Y[54]) | (ZNaNM&~Addend[54]);
|
|
assign Invalid = SigNaN | ((XInfM || YInfM) & ZInfM & (PSgn ^ ZSgn) & ~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[12]&~(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[12] | ((SumExp == 0) & (Round|Guard|Sticky|UfGuard)))&~(XNaNM|YNaNM|ZNaNM|XInfM|YInfM|ZInfM);
|
|
assign UnderflowFlag = (FullResultExp[12] | ((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|UfGuard|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};
|
|
|
|
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|
|
///////////////////////////////////////////////////////////////////////////////
|
|
// Select the result
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
assign XNaNResult = FmtM ? {XSgn, X[62:52], 1'b1,X[50:0]} : {XSgn, X[62:55], 1'b1,X[53:0]};
|
|
assign YNaNResult = FmtM ? {YSgn, Y[62:52], 1'b1,Y[50:0]} : {YSgn, Y[62:55], 1'b1,Y[53:0]};
|
|
assign ZNaNResult = FmtM ? {ZSgn, Addend[62:52], 1'b1,Addend[50:0]} : {ZSgn, Addend[62:55], 1'b1,Addend[53:0]};
|
|
assign OverflowResult = FmtM ? ((FrmM[1:0]==2'b01) | (FrmM[1:0]==2'b10&~ResultSgn) | (FrmM[1:0]==2'b11&ResultSgn)) ? {ResultSgn, 11'h7fe, {52{1'b1}}} :
|
|
{ResultSgn, 11'h7ff, 52'b0} :
|
|
((FrmM[1:0]==2'b01) | (FrmM[1:0]==2'b10&~ResultSgn) | (FrmM[1:0]==2'b11&ResultSgn)) ? {ResultSgn, 8'hfe, {23{1'b1}}, 32'b0} :
|
|
{ResultSgn, 8'hff, 55'b0};
|
|
assign InvalidResult = FmtM ? {ResultSgn, 11'h7ff, 1'b1, 51'b0} : {ResultSgn, 8'hff, 1'b1, 54'b0};
|
|
assign KillProdResult = FmtM ?{ResultSgn, Addend[62:0] - {62'b0, (Minus1&AddendStickyM)}} + {62'b0, (Plus1&AddendStickyM)} : {ResultSgn, Addend[62:32] - {30'b0, (Minus1&AddendStickyM)} + {30'b0, (Plus1&AddendStickyM)}, 32'b0};
|
|
assign UnderflowResult = FmtM ? {ResultSgn, 63'b0} + {63'b0, (CalcPlus1&(AddendStickyM|FrmM[1]))} : {{ResultSgn, 31'b0} + {31'b0, (CalcPlus1&(AddendStickyM|FrmM[1]))}, 32'b0};
|
|
assign FMAResM = XNaNM ? XNaNResult :
|
|
YNaNM ? YNaNResult :
|
|
ZNaNM ? ZNaNResult :
|
|
Invalid ? InvalidResult : // has to be before inf
|
|
XInfM ? {PSgn, X[62:0]} :
|
|
YInfM ? {PSgn, Y[62:0]} :
|
|
ZInfM ? {ZSgn, Addend[62:0]} :
|
|
Overflow ? OverflowResult :
|
|
KillProdM ? KillProdResult : // has to be after Underflow
|
|
Underflow & ~ResultDenorm ? UnderflowResult :
|
|
FmtM ? {ResultSgn, ResultExp, ResultFrac} :
|
|
{ResultSgn, ResultExp[7:0], ResultFrac, 3'b0};
|
|
|
|
|
|
|
|
endmodule |