forked from Github_Repos/cvw
66 lines
3.2 KiB
Systemverilog
66 lines
3.2 KiB
Systemverilog
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///////////////////////////////////////////
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// page_number_mixer.sv
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//
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// Written: tfleming@hmc.edu & jtorrey@hmc.edu 6 April 2021
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// Modified: kmacsaigoren@hmc.edu 1 June 2021
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// Implemented SV48 on top of SV39. This included adding a 3rd Segment to each of the pagenumbers,
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// Ensuring that the BITS and HIGH_SEGMENT_BITS inputs were correct everywhere this module gets instatniated,
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// Adding seveeral muxes to decide the bit selection to turn pagenumbers into segments based on SV mode,
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// Adding support for terapage/newgigapage encoding.
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//
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// Purpose: Takes two page numbers and replaces segments of the first page
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// number with segments from the second, based on the page type.
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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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module physicalpagemask #(parameter BITS = 20,
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parameter HIGH_SEGMENT_BITS = 10) (
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input [BITS-1:0] **** VirtualAddress,
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input [BITS-1:0] *** PPN,
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input [1:0] PageType,
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input [`SVMODE_BITS-1:0] SvMode,
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output [BITS-1:0]*** PhysicalAddress
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);
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logic [***] OffsetMask;
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generate
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if (`XLEN == 32) begin
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always_comb
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case (PageType[0])
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0: OffsetMask = 34'h3FFFFF000; // kilopage: 22 bits of PPN, 12 bits of offset
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1: OffsetMask = 34'h3FFC00000; // megapage: 12 bits of PPN, 22 bits of offset
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endcase
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end else begin
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always_comb
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case (PageType[1:0])
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0: OffsetMask = 56'hFFFFFFFFFFF000; // kilopage: 44 bits of PPN, 12 bits of offset
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1: OffsetMask = 56'hFFFFFFFFE00000; // megapage: 35 bits of PPN, 21 bits of offset
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2: OffsetMask = 56'hFFFFFFC0000000; // gigapage: 26 bits of PPN, 30 bits of offset
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3: OffsetMask = 56'hFFFF8000000000; // terapage: 17 bits of PPN, 39 bits of offset
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endcase
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endgenerate
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// merge low bits of the virtual address containing the offset with high bits of the PPN
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assign PhysicalAddress = VirtualAddress & ~OffsetMask | ((PPN<<12) & OffsetMask);
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endmodule
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