forked from Github_Repos/cvw
58 lines
2.5 KiB
Systemverilog
58 lines
2.5 KiB
Systemverilog
///////////////////////////////////////////
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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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// 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 extend (
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input logic [31:7] InstrD,
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input logic [2:0] ImmSrcD,
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output logic [`XLEN-1:0 ] ExtImmD);
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localparam [`XLEN-1:0] undefined = {(`XLEN){1'bx}}; // could change to 0 after debug
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always_comb
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case(ImmSrcD)
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// I-type
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3'b000: ExtImmD = {{(`XLEN-12){InstrD[31]}}, InstrD[31:20]};
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// S-type (stores)
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3'b001: ExtImmD = {{(`XLEN-12){InstrD[31]}}, InstrD[31:25], InstrD[11:7]};
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// B-type (branches)
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3'b010: ExtImmD = {{(`XLEN-12){InstrD[31]}}, InstrD[7], InstrD[30:25], InstrD[11:8], 1'b0};
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// J-type (jal)
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3'b011: ExtImmD = {{(`XLEN-20){InstrD[31]}}, InstrD[19:12], InstrD[20], InstrD[30:21], 1'b0};
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// U-type (lui, auipc)
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3'b100: ExtImmD = {{(`XLEN-31){InstrD[31]}}, InstrD[30:12], 12'b0};
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// Store Conditional: zero offset
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3'b101: if (`A_SUPPORTED) ExtImmD = 0;
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else ExtImmD = undefined;
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default: ExtImmD = undefined; // undefined
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endcase
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endmodule
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