cvw/pipelined/src/privileged/privdec.sv

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///////////////////////////////////////////
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// privdec.sv
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//
// Written: David_Harris@hmc.edu 9 January 2021
// Modified:
//
// Purpose: Decode Privileged & related instructions
// See RISC-V Privileged Mode Specification 20190608 3.1.10-11
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
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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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//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
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`include "wally-config.vh"
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module privdec (
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input logic [31:20] InstrM,
input logic PrivilegedM, IllegalIEUInstrFaultM, IllegalCSRAccessM, IllegalFPUInstrM, TrappedSRETM,
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input logic [1:0] PrivilegeModeW,
input logic STATUS_TSR,
output logic IllegalInstrFaultM,
output logic uretM, sretM, mretM, ecallM, ebreakM, wfiM, sfencevmaM);
logic IllegalPrivilegedInstrM;
// xRET defined in Privileged Spect 3.2.2
assign uretM = PrivilegedM & (InstrM[31:20] == 12'b000000000010) & `N_SUPPORTED;
assign sretM = PrivilegedM & (InstrM[31:20] == 12'b000100000010) & `S_SUPPORTED &
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PrivilegeModeW[0] & ~STATUS_TSR;
assign mretM = PrivilegedM & (InstrM[31:20] == 12'b001100000010) & (PrivilegeModeW == `M_MODE);
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assign ecallM = PrivilegedM & (InstrM[31:20] == 12'b000000000000);
assign ebreakM = PrivilegedM & (InstrM[31:20] == 12'b000000000001);
assign wfiM = PrivilegedM & (InstrM[31:20] == 12'b000100000101);
assign sfencevmaM = PrivilegedM & (InstrM[31:25] == 7'b0001001);
assign IllegalPrivilegedInstrM = PrivilegedM & ~(uretM|sretM|mretM|ecallM|ebreakM|wfiM|sfencevmaM);
assign IllegalInstrFaultM = (IllegalIEUInstrFaultM & IllegalFPUInstrM) | IllegalPrivilegedInstrM | IllegalCSRAccessM | TrappedSRETM; // *** generalize this for other instructions
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// *** initially, wfi is nop
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endmodule