forked from Github_Repos/cvw
50 lines
2.2 KiB
Systemverilog
50 lines
2.2 KiB
Systemverilog
///////////////////////////////////////////
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//
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// Written: 6/23/2021 me@KatherineParry.com, David_Harris@hmc.edu
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// Modified:
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//
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// Purpose: FMA Sign Logic
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//
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// A component of the Wally configurable RISC-V project.
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//
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// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
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//
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// MIT LICENSE
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// software and associated documentation files (the "Software"), to deal in the Software
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// without restriction, including without limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
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// to whom the Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all copies or
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// substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
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// OR OTHER DEALINGS IN THE SOFTWARE.
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////////////////////////////////////////////////////////////////////////////////////////////////
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`include "wally-config.vh"
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module fmasign(
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input logic [2:0] OpCtrl, // opperation contol
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input logic Xs, Ys, Zs, // sign of the inputs
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output logic Ps, // the product's sign - takes opperation into account
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output logic As, // aligned addend sign used in fma - takes opperation into account
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output logic InvA // Effective subtraction: invert addend
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);
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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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// flip is negation opperation
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assign Ps = Xs ^ Ys ^ (OpCtrl[1]&~OpCtrl[2]);
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// flip addend sign for subtraction
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assign As = Zs^OpCtrl[0];
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// Effective subtraction when product and addend have opposite signs
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assign InvA = As ^ Ps;
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endmodule
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