forked from Github_Repos/cvw
64 lines
2.4 KiB
Systemverilog
64 lines
2.4 KiB
Systemverilog
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///////////////////////////////////////////
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// fdivsqrtqsel2.sv
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//
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// Written: David_Harris@hmc.edu, me@KatherineParry.com, cturek@hmc.edu
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// Modified:13 January 2022
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//
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// Purpose: Radix 2 Quotient Digit Selection
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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 fdivsqrtqsel2 (
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input logic [3:0] ps, pc,
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output logic qp, qz, qn
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);
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logic [3:0] p, g;
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logic magnitude, sign, cout;
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// The quotient selection logic is presented for simplicity, not
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// for efficiency. You can probably optimize your logic to
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// select the proper divisor with less delay.
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// Qmient equations from EE371 lecture notes 13-20
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assign p = ps ^ pc;
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assign g = ps & pc;
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//assign magnitude = ~(&p[2:0]);
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assign cout = g[2] | (p[2] & (g[1] | p[1] & g[0]));
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//assign sign = p[3] ^ cout;
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assign magnitude = ~((ps[2]^pc[2]) & (ps[1]^pc[1]) &
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(ps[0]^pc[0]));
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assign sign = (ps[3]^pc[3])^
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(ps[2] & pc[2] | ((ps[2]^pc[2]) &
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(ps[1]&pc[1] | ((ps[1]^pc[1]) &
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(ps[0]&pc[0])))));
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// Produce quotient = +1, 0, or -1
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assign qp = magnitude & ~sign;
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assign qz = ~magnitude;
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assign qn = magnitude & sign;
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endmodule
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