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56 lines
2.9 KiB
Systemverilog
56 lines
2.9 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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// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
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// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
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// 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 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, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR 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, TORT OR OTHERWISE, ARISING FROM, OUT
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// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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///////////////////////////////////////////
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`include "wally-config.vh"
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`include "wally-constants.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 [1:0] PrivilegeModeW,
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input logic STATUS_TSR,
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output logic IllegalInstrFaultM,
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output logic uretM, 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 uretM = PrivilegedM & (InstrM[31:20] == 12'b000000000010) & `N_SUPPORTED;
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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);
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assign IllegalPrivilegedInstrM = PrivilegedM & ~(uretM|sretM|mretM|ecallM|ebreakM|wfiM|sfencevmaM);
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assign IllegalInstrFaultM = (IllegalIEUInstrFaultM & IllegalFPUInstrM) | IllegalPrivilegedInstrM | IllegalCSRAccessM; // *** generalize this for other instructions
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// *** initially, wfi and sfencevma are nop
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// *** zfenci extension?
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endmodule
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