Simplified superpage matching

wally-pipelined/src/mmu/page_number_mixer.sv

@@ -51,6 +51,7 @@ module page_number_mixer #(parameter BITS = 20,
 
   generate
     if (`XLEN == 32) begin
+      always_comb 
 
       logic [HIGH_SEGMENT_BITS-1:0] Segment1, MixSegment1, Segment1Combined;
       logic [LOW_SEGMENT_BITS-1:0]  Segment0, MixSegment0, Segment0Combined;

wally-pipelined/src/mmu/physicalpagemask.sv

@@ -0,0 +1,65 @@
+///////////////////////////////////////////
+// page_number_mixer.sv
+//
+// Written: tfleming@hmc.edu & jtorrey@hmc.edu 6 April 2021
+// Modified: kmacsaigoren@hmc.edu 1 June 2021
+//              Implemented SV48 on top of SV39. This included adding a 3rd Segment to each of the pagenumbers,
+//              Ensuring that the BITS and HIGH_SEGMENT_BITS inputs were correct everywhere this module gets instatniated,
+//              Adding seveeral muxes to decide the bit selection to turn pagenumbers into segments based on SV mode,
+//              Adding support for terapage/newgigapage encoding.
+//
+// Purpose: Takes two page numbers and replaces segments of the first page
+//          number with segments from the second, based on the page type.
+// 
+// A component of the Wally configurable RISC-V project.
+// 
+// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
+//
+// 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:
+//
+// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+//
+// 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.
+///////////////////////////////////////////
+
+`include "wally-config.vh"
+
+module physicalpagemask #(parameter BITS = 20,
+                           parameter HIGH_SEGMENT_BITS = 10) (
+    input  [BITS-1:0]  ****       VirtualAddress,
+    input  [BITS-1:0] ***        PPN,
+    input  [1:0]              PageType,
+    input  [`SVMODE_BITS-1:0] SvMode,
+
+    output [BITS-1:0]***         PhysicalAddress
+);
+
+  logic [***] OffsetMask;
+
+  generate
+    if (`XLEN == 32) begin
+      always_comb 
+        case (PageType[0])
+          0: OffsetMask = 34'h3FFFFF000; // kilopage: 22 bits of PPN, 12 bits of offset
+          1: OffsetMask = 34'h3FFC00000; // megapage: 12 bits of PPN, 22 bits of offset
+        endcase
+    end else begin
+      always_comb 
+        case (PageType[1:0])
+          0: OffsetMask = 56'hFFFFFFFFFFF000; // kilopage: 44 bits of PPN, 12 bits of offset
+          1: OffsetMask = 56'hFFFFFFFFE00000; // megapage: 35 bits of PPN, 21 bits of offset
+          2: OffsetMask = 56'hFFFFFFC0000000; // gigapage: 26 bits of PPN, 30 bits of offset
+          3: OffsetMask = 56'hFFFF8000000000; // terapage: 17 bits of PPN, 39 bits of offset
+        endcase
+  endgenerate
+
+  // merge low bits of the virtual address containing the offset with high bits of the PPN
+  assign PhysicalAddress = VirtualAddress & ~OffsetMask | ((PPN<<12) & OffsetMask);
+
+endmodule