began updating cam line to reduce muxes, confusion

wally-pipelined/src/mmu/cam_line.sv

@@ -29,7 +29,7 @@
 `include "wally-config.vh"
 
 module cam_line #(parameter KEY_BITS = 20,
-                  parameter HIGH_SEGMENT_BITS = 10) (
+                  parameter SEGMENT_BITS = 10) (
   input                 clk, reset,
 
   // input to check which SvMode is running
@@ -58,6 +58,36 @@ module cam_line #(parameter KEY_BITS = 20,
   logic                Valid;
   logic [KEY_BITS-1:0] Key;
   
+
+  // Split up key and VPN into sections for each page table level.
+  logic [SEGMENT_BITS-1:0] Key0, Key1, VPN0, VPN1;
+  logic MatchVPN0, MatchVPN1;
+
+  generate
+    if (`XLEN == 32) begin
+      assign {Key1, Key0} = Key;
+      assign {VPN1, VPN0} = VirtualPageNumber;
+
+      assign MatchVPN0 = (VPN0 == Key0) || (PageType[0]); // least signifcant section
+      assign MatchVPN1 = (VPN1 == Key1);
+
+      assign Match = MatchVPN0 & MatchVPN1 & Valid;
+    end else begin
+      logic [SEGMENT_BITS-1:0] Key2, Key3, VPN2, VPN3;
+      logic MatchVPN2, MatchVPN3;
+
+      assign {VPN3, VPN2, VPN1, VPN0} = VirtualPageNumber;
+      assign {Key3, Key2, Key1, Key0} = Key;
+
+      assign MatchVPN0 = (VPN0 == Key0) || (PageType > 2'd0); // least signifcant section
+      assign MatchVPN1 = (VPN1 == Key1) || (PageType > 2'd1);
+      assign MatchVPN2 = (VPN2 == Key2) || (PageType > 2'd2);
+      assign MatchVPN3 = (VPN3 == Key3); // *** this should always match in sv39 since both vPN3 and key3 are zeroed by the pagetable walker before getting to the cam
+      
+      assign Match = MatchVPN0 & MatchVPN1 & MatchVPN2 & MatchVPN3 & Valid;
+    end
+  endgenerate
+
   // When determining a match for a superpage, we might use only a portion of
   // the input VirtualPageNumber. Unused parts of the VirtualPageNumber are
   // zeroed in VirtualPageNumberQuery to better match with Key.
@@ -77,8 +107,17 @@ module cam_line #(parameter KEY_BITS = 20,
   // Calculate the actual query key based on the input key and the page type.
   // For example, a megapage in SV39 only cares about VPN2 and VPN1, so VPN0
   // should automatically match.
-  page_number_mixer #(KEY_BITS, HIGH_SEGMENT_BITS) mixer(VirtualPageNumber, Key, PageType, SvMode, VirtualPageNumberQuery);
+//  logic [KEY_BITS-1:0] PageNumberMask, MaskedKey, MaskedQuery;
+  // this is the max possible length of the vpn, as listed in wally-constants.
+  // for modes with a mode with fewer bits in the vpn, the extra levels in MaskedQuery 
+  // and MaskedKey should have been zeroed out by the tlb before coming through the cam as VirtualPageNumber.
+  generate
+      if (`XLEN == 32) begin
+
+      end else begin
+
+      end
+  endgenerate
 
-  assign Match = ({1'b1, VirtualPageNumberQuery} == {Valid, Key});
 
 endmodule

wally-pipelined/src/mmu/page_number_mixer.sv

@@ -51,7 +51,6 @@ 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/tlb_cam.sv

@@ -30,7 +30,7 @@
 
 module tlb_cam #(parameter ENTRY_BITS = 3,
                  parameter KEY_BITS   = 20,
-                 parameter HIGH_SEGMENT_BITS = 10) (
+                 parameter SEGMENT_BITS = 10) (
   input                     clk, reset,
   input  [KEY_BITS-1:0]     VirtualPageNumber,
   input  [1:0]              PageTypeWrite,
@@ -60,7 +60,7 @@ module tlb_cam #(parameter ENTRY_BITS = 3,
   generate
     genvar i;
     for (i = 0; i < NENTRIES; i++) begin
-      cam_line #(KEY_BITS, HIGH_SEGMENT_BITS) cam_line(
+      cam_line #(KEY_BITS, SEGMENT_BITS) cam_line(
         .CAMLineWrite(CAMLineWrite[i] && TLBWrite),
         .PageType(PageTypeList[i]),
         .Match(Matches[i]),