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58 lines
3.0 KiB
Systemverilog
58 lines
3.0 KiB
Systemverilog
///////////////////////////////////////////
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// privdec.sv
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//
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// Written: David_Harris@hmc.edu 9 January 2021
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// Modified:
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//
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// Purpose: Decode Privileged & related instructions
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// See RISC-V Privileged Mode Specification 20190608 3.1.10-11
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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 privdec (
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input logic [31:20] InstrM,
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input logic PrivilegedM, IllegalIEUInstrFaultM, IllegalCSRAccessM, IllegalFPUInstrM,
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input logic TrappedSRETM, WFITimeoutM,
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input logic [1:0] PrivilegeModeW,
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input logic STATUS_TSR,
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output logic IllegalInstrFaultM,
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output logic sretM, mretM, ecallM, ebreakM, wfiM, sfencevmaM);
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logic IllegalPrivilegedInstrM;
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// xRET defined in Privileged Spect 3.2.2
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assign sretM = PrivilegedM & (InstrM[31:20] == 12'b000100000010) & `S_SUPPORTED &
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PrivilegeModeW[0] & ~STATUS_TSR;
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assign mretM = PrivilegedM & (InstrM[31:20] == 12'b001100000010) & (PrivilegeModeW == `M_MODE);
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assign ecallM = PrivilegedM & (InstrM[31:20] == 12'b000000000000);
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assign ebreakM = PrivilegedM & (InstrM[31:20] == 12'b000000000001);
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assign wfiM = PrivilegedM & (InstrM[31:20] == 12'b000100000101);
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assign sfencevmaM = PrivilegedM & (InstrM[31:25] == 7'b0001001); // *** & (PrivilegedModeW == `M_MODE | ~STATUS_TVM); // *** does this work in U mode?
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assign IllegalPrivilegedInstrM = PrivilegedM & ~(sretM|mretM|ecallM|ebreakM|wfiM|sfencevmaM);
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assign IllegalInstrFaultM = (IllegalIEUInstrFaultM & IllegalFPUInstrM) | IllegalPrivilegedInstrM | IllegalCSRAccessM |
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TrappedSRETM | WFITimeoutM; // *** generalize this for other instructions
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endmodule
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