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FMA cleanup

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This commit is contained in:
David Harris 2022-08-02 07:42:32 -07:00
parent baeafc4fd2
commit b13cdf79b3
1 changed files with 3 additions and 6 deletions
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9
pipelined/src/fpu/fmaadd.sv
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@ -51,10 +51,10 @@ module fmaadd(
// Addition // Addition
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
// Choose an inverted or non-inverted addend - the one has to be added now for the LZA // Choose an inverted or non-inverted addend. Put carry into adder/LZA for addition
assign AmInv = InvA ? ~Am : Am; assign AmInv = InvA ? ~Am : Am;
// 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 PmKilled = Pm&{2*`NF+2{~KillProd}}; assign PmKilled = KillProd ? '0 : Pm;
// Do the addition // Do the addition
// - calculate a positive and negitive sum in parallel // - calculate a positive and negitive sum in parallel
// Zsticky Psticky // Zsticky Psticky
@ -64,15 +64,12 @@ module fmaadd(
assign {NegSum, PreSum} = {{`NF+3{1'b0}}, PmKilled, 1'b0, InvA&ZmSticky&KillProd} + {InvA, AmInv} + {{3*`NF+6{1'b0}}, InvA&~((ZmSticky&~KillProd))}; assign {NegSum, PreSum} = {{`NF+3{1'b0}}, PmKilled, 1'b0, InvA&ZmSticky&KillProd} + {InvA, AmInv} + {{3*`NF+6{1'b0}}, InvA&~((ZmSticky&~KillProd))};
assign NegPreSum = Am + {{`NF+2{1'b1}}, ~PmKilled, 2'b11} + {(3*`NF+4)'(0), ZmSticky&~KillProd, ~(ZmSticky)}; assign NegPreSum = Am + {{`NF+2{1'b1}}, ~PmKilled, 2'b11} + {(3*`NF+4)'(0), ZmSticky&~KillProd, ~(ZmSticky)};
// Is the sum negitive
// assign NegSum = PreSum[3*`NF+6];
// Choose the positive sum and accompanying LZA result. // Choose the positive sum and accompanying LZA result.
assign Sm = NegSum ? NegPreSum : PreSum; assign Sm = NegSum ? NegPreSum : PreSum;
// is the result negitive // is the result negitive
// if p - z is the Sum negitive // if p - z is the Sum negitive
// if -p + z is the Sum positive // if -p + z is the Sum positive
// if -p - z then the Sum is negitive // if -p - z then the Sum is negitive
assign Ss = NegSum^Ps; //*** move to execute stage assign Ss = NegSum^Ps;
assign Se = KillProd ? {2'b0, Ze} : Pe; assign Se = KillProd ? {2'b0, Ze} : Pe;
endmodule endmodule