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67 lines
2.5 KiB
Systemverilog
67 lines
2.5 KiB
Systemverilog
///////////////////////////////////////////
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// swbytemask.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: On-chip RAM, external to core
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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 swbytemask (
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input logic [1:0] Size,
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input logic [2:0] Adr,
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output logic [`XLEN/8-1:0] ByteMask);
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if(`XLEN == 64) begin
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always_comb begin
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case(Size[1:0])
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2'b00: begin ByteMask = 8'b00000000; ByteMask[Adr[2:0]] = 1; end // sb
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2'b01: case (Adr[2:1])
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2'b00: ByteMask = 8'b0000_0011;
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2'b01: ByteMask = 8'b0000_1100;
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2'b10: ByteMask = 8'b0011_0000;
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2'b11: ByteMask = 8'b1100_0000;
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endcase
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2'b10: if (Adr[2]) ByteMask = 8'b11110000;
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else ByteMask = 8'b00001111;
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2'b11: ByteMask = 8'b1111_1111;
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endcase
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end
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end else begin
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always_comb begin
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case(Size[1:0])
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2'b00: begin ByteMask = 4'b0000; ByteMask[Adr[1:0]] = 1; end // sb
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2'b01: if (Adr[1]) ByteMask = 4'b1100;
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else ByteMask = 4'b0011;
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2'b10: ByteMask = 4'b1111;
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default: ByteMask = 4'b1111;
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endcase
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end
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end
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endmodule
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