forked from Github_Repos/cvw
29 lines
2.1 KiB
Systemverilog
29 lines
2.1 KiB
Systemverilog
|
`include "wally-config.vh"
|
||
|
|
|
||
|
|
module lzacorrection(
|
||
|
|
input logic [`NORMSHIFTSZ-1:0] Shifted, // the shifted sum before LZA correction
|
||
|
|
input logic FmaOp,
|
||
|
|
input logic [`NE+1:0] ConvNormSumExp, // exponent of the normalized sum not taking into account denormal or zero results
|
||
|
|
input logic PreResultDenorm, // is the result denormalized - calculated before LZA corection
|
||
|
|
input logic KillProdM, // is the product set to zero
|
||
|
|
input logic SumZero,
|
||
|
|
output logic [`CORRSHIFTSZ-1:0] CorrShifted, // the shifted sum before LZA correction
|
||
|
|
output logic [`NE+1:0] SumExp // exponent of the normalized sum
|
||
|
|
);
|
||
|
|
logic [3*`NF+5:0] CorrSumShifted; // the shifted sum after LZA correction
|
||
|
|
logic ResDenorm; // is the result denormalized
|
||
|
|
logic LZAPlus1, LZAPlus2; // add one or two to the sum's exponent due to LZA correction
|
||
|
|
|
||
|
|
// LZA correction
|
||
|
|
assign LZAPlus1 = Shifted[`NORMSHIFTSZ-2];
|
||
|
|
assign LZAPlus2 = Shifted[`NORMSHIFTSZ-1];
|
||
|
|
// the only possible mantissa for a plus two is all zeroes - a one has to propigate all the way through a sum. so we can leave the bottom statement alone
|
||
|
|
assign CorrSumShifted = LZAPlus1 ? Shifted[`NORMSHIFTSZ-3:1] : Shifted[`NORMSHIFTSZ-4:0];
|
||
|
|
assign CorrShifted = FmaOp ? {CorrSumShifted, {`CORRSHIFTSZ-(3*`NF+6){1'b0}}} : Shifted[`NORMSHIFTSZ-1:`NORMSHIFTSZ-`CORRSHIFTSZ];
|
||
|
|
// Determine sum's exponent
|
||
|
|
// if plus1 If plus2 if said denorm but norm plus 1 if said denorm but norm plus 2
|
||
|
|
assign SumExp = (ConvNormSumExp+{{`NE+1{1'b0}}, LZAPlus1&~KillProdM}+{{`NE{1'b0}}, LZAPlus2&~KillProdM, 1'b0}+{{`NE+1{1'b0}}, ~ResDenorm&PreResultDenorm&~KillProdM}+{{`NE+1{1'b0}}, &ConvNormSumExp&Shifted[3*`NF+6]&~KillProdM}) & {`NE+2{~(SumZero|ResDenorm)}};
|
||
|
|
// recalculate if the result is denormalized
|
||
|
|
assign ResDenorm = PreResultDenorm&~Shifted[`NORMSHIFTSZ-3]&~Shifted[`NORMSHIFTSZ-2];
|
||
|
|
|
||
|
|
endmodule
|