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Simplify unpacker

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This commit is contained in:
David Harris 2021-07-22 13:40:42 -04:00
parent 44141047ef
commit 19dac66264
2 changed files with 17 additions and 15 deletions
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2
wally-pipelined/src/fpu/fma.sv
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@ -183,7 +183,7 @@ module fma2(
input logic XSgnM, YSgnM, ZSgnM,
input logic [`NE-1:0] XExpM, YExpM, ZExpM,
input logic [`NF-1:0] XManM, YManM, ZManM,
input logic [`NF:0] XManM, YManM, ZManM,
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

30
wally-pipelined/src/fpu/unpacking.sv
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@ -16,7 +16,7 @@ module unpacking (
);
//***rename to make significand = 1.frac m = significand
logic [51:0] XFracE, YFracE, ZFracE;
logic XAssumed1E, YAssumed1E, ZAssumed1E;
logic XExpNonzero, YExpNonzero, ZExpNonzero;
logic XFracZero, YFracZero, ZFracZero; // input fraction zero
logic XExpZero, YExpZero, ZExpZero; // input exponent zero
logic [63:0] Addend; // value to add (Z or zero)
@ -27,6 +27,7 @@ module unpacking (
assign YSgnE = FmtE ? Y[63] : Y[31];
assign ZSgnE = FmtE ? Addend[63]^FOpCtrlE[0] : Addend[31]^FOpCtrlE[0]; // *** Maybe this should be done in the FMA for modularity?
//assign XExpE = FmtE ? X[62:52] : {X[30], {3{~X[30]&~XExpZero|XExpMaxE}}, X[29:23]};
assign XExpE = FmtE ? X[62:52] : {3'b0, X[30:23]}; // *** maybe convert to full number of bits here?
assign YExpE = FmtE ? Y[62:52] : {3'b0, Y[30:23]};
assign ZExpE = FmtE ? Addend[62:52] : {3'b0, Addend[30:23]};
@ -35,26 +36,26 @@ module unpacking (
assign YFracE = FmtE ? Y[51:0] : {Y[22:0], 29'b0};
assign ZFracE = FmtE ? Addend[51:0] : {Addend[22:0], 29'b0};
assign XAssumed1E = |XExpE; // *** should these be prepended now to create a significand?
assign YAssumed1E = |YExpE;
assign ZAssumed1E = |ZExpE;
assign XExpNonzero = FmtE ? |X[62:52] : |X[30:23];
assign YExpNonzero = FmtE ? |Y[62:52] : |Y[30:23];
assign ZExpNonzero = FmtE ? |Addend[62:52] : |Addend[30:23];
assign XManE = {XAssumed1E, XFracE};
assign YManE = {YAssumed1E, YFracE};
assign ZManE = {ZAssumed1E, ZFracE};
assign XManE = {XExpNonzero, XFracE};
assign YManE = {YExpNonzero, YFracE};
assign ZManE = {ZExpNonzero, ZFracE};
assign XExpZero = ~XAssumed1E;
assign YExpZero = ~YAssumed1E;
assign ZExpZero = ~ZAssumed1E;
assign XExpZero = ~XExpNonzero;
assign YExpZero = ~YExpNonzero;
assign ZExpZero = ~ZExpNonzero;
assign XFracZero = ~|XFracE;
assign YFracZero = ~|YFracE;
assign ZFracZero = ~|ZFracE;
assign XExpMaxE = FmtE ? &XExpE[10:0] : &XExpE[7:0];
assign YExpMaxE = FmtE ? &YExpE[10:0] : &YExpE[7:0];
assign ZExpMaxE = FmtE ? &ZExpE[10:0] : &ZExpE[7:0];
assign XExpMaxE = FmtE ? &X[62:52] : &X[30:23];
assign YExpMaxE = FmtE ? &Y[62:52] : &Y[30:23];
assign ZExpMaxE = FmtE ? &Z[62:52] : &Z[30:23];
assign XNormE = ~(XExpMaxE|XExpZero);
assign XNaNE = XExpMaxE & ~XFracZero;
@ -78,5 +79,6 @@ module unpacking (
assign ZZeroE = ZExpZero & ZFracZero;
assign BiasE = FmtE ? 13'h3ff : 13'h7f; // *** is it better to convert to full precision exponents so bias isn't needed?
//assign BiasE = 13'h3ff; // always use 1023 because exponents are unpacked to double precision
endmodule