forked from Github_Repos/cvw
50 lines
2.3 KiB
Systemverilog
50 lines
2.3 KiB
Systemverilog
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///////////////////////////////////////////
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// extend.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:
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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-macros.sv"
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module extend #(parameter XLEN=32) (
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input logic [31:7] instr,
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input logic [2:0] immsrc,
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output logic [XLEN-1:0] immext);
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always_comb
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case(immsrc)
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// I-type
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3'b000: immext = {{(XLEN-12){instr[31]}}, instr[31:20]};
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// S-type (stores)
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3'b001: immext = {{(XLEN-12){instr[31]}}, instr[31:25], instr[11:7]};
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// B-type (branches)
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3'b010: immext = {{(XLEN-12){instr[31]}}, instr[7], instr[30:25], instr[11:8], 1'b0};
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// J-type (jal)
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3'b011: immext = {{(XLEN-20){instr[31]}}, instr[19:12], instr[20], instr[30:21], 1'b0};
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// U-type (lui, auipc)
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3'b100: immext = {{(XLEN-31){instr[31]}}, instr[30:12], 12'b0};
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/* verilator lint_off WIDTH */
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default: immext = 'bx; // undefined
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/* verilator lint_on WIDTH */
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endcase
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endmodule
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