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`include "FT64_defines.vh"
`include "FT64_config.vh"
//=============================================================================
//        __
//   \\__/ o\    (C) 2011-2019  Robert Finch, Waterloo
//    \  __ /    All rights reserved.
//     \/_//     robfinch<remove>@finitron.ca
//       ||
//  
//      FT64_TLB.v
//
//  
// This source file is free software: you can redistribute it and/or modify 
// it under the terms of the GNU Lesser General Public License as published 
// by the Free Software Foundation, either version 3 of the License, or     
// (at your option) any later version.                                      
//                                                                          
// This source file is distributed in the hope that it will be useful,      
// but WITHOUT ANY WARRANTY; without even the implied warranty of           
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            
// GNU General Public License for more details.                             
//                                                                          
// You should have received a copy of the GNU General Public License        
// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
//                                                                          
//
// TLB
// The TLB contains 256 entries, that are 16 way set associative.
// The TLB is shared between the instruction and data streams.
// The code is carefully constructed to not require reset signals.
//
//=============================================================================
//
`define TLBMissPage             {DBW-13{1'b1}}
 
module FT64_TLB(clk, ld, done, idle, ol,
        ASID, op, regno, dati, dato,
        uncached,
        icl_i, cyc_i, we_i, vadr_i, cyc_o, we_o, padr_o,
        wrv_o, rdv_o, exv_o,
        TLBMiss, HTLBVirtPageo);
parameter DBW=64;
parameter ABW=32;
parameter ENTRIES=256;
parameter IDLE = 4'd0;
parameter ONE = 4'd1;
parameter TWO = 4'd2;
parameter READ = 4'd1;
parameter INC1 = 4'd2;
parameter INC2 = 4'd3;
parameter INC3 = 4'd4;
parameter AGE1 = 4'd5;
parameter AGE2 = 4'd6;
input clk;
input ld;
output done;
output idle;
input [1:0] ol;                                  // operating level
input [ABW-1:0] vadr_i;
output reg [ABW-1:0] padr_o = 64'hFFFFFFFFFFFC0100;
output uncached;
 
input icl_i;
input cyc_i;
input we_i;
output reg cyc_o;
output reg we_o;
output reg exv_o;
output reg wrv_o;
output reg rdv_o;
input [7:0] ASID;
input [3:0] op;
input [3:0] regno;
input [DBW-1:0] dati;
output reg [DBW-1:0] dato;
output TLBMiss;
output [DBW-1:0] HTLBVirtPageo;
 
integer n;
 
reg [1:0] state = IDLE;
assign done = state==(IDLE && !ld) || state==TWO;
assign idle = state==IDLE && !ld;
 
// Holding registers
// These allow the TLB to updated in a single cycle as a unit
reg [DBW-1:0] HTLBVirtPage;
assign HTLBVirtPageo = {HTLBVirtPage,13'b0};
reg [DBW-1:0] HTLBPhysPage;
reg [7:0] HTLBASID;
reg HTLBG;
reg HTLBD;
reg HTLBR, HTLBW, HTLBX, HTLBA, HTLBU, HTLBS;
reg [2:0] HTLBC;
reg [7:0] HTLBPL;
reg [2:0] HTLBPageSize;
reg HTLBValid;
reg [ABW-1:0] miss_addr;
 
reg TLBenabled = 1'b0;
reg [7:0] i = 8'h00;
reg [DBW-1:0] Index;
reg [3:0] Random = 4'hF;
reg [3:0] Wired = 4'd0;
reg [2:0] PageSize;
reg [15:0] Match;
 
reg [4:0] q;
wire doddpage;
reg [DBW-1:0] TLBVirtPage [ENTRIES-1:0];
reg [ENTRIES-1:0] TLBG;
reg [ENTRIES-1:0] TLBD;
reg [ENTRIES-1:0] TLBU;
reg [ENTRIES-1:0] TLBS;
reg [ENTRIES-1:0] TLBA;
reg [2:0] TLBC [ENTRIES-1:0];
reg [7:0] TLBASID [ENTRIES-1:0];
reg [7:0] TLBPL [ENTRIES-1:0];
reg [2:0] TLBPageSize [255:0];
reg [ENTRIES-1:0] TLBValid;
reg [DBW-1:0] imiss_addr;
reg [DBW-1:0] dmiss_addr;
reg [DBW-1:0] PageTblAddr = {DBW{1'b0}};
reg [DBW-1:0] PageTblCtrl = {DBW{1'b0}};
 
reg [23:0] age_lmt = 24'd20000;
reg [23:0] age_ctr = 24'd0;
wire age_tick = age_ctr < 24'd5;
reg cyc_en = 1'b1, age_en = 1'b1;
reg [3:0] ar_state = IDLE;
reg ar_wr = 1'b0;
reg [7:0] age_adr = 8'h00, ar_adr = 8'h00;
reg [32:0] count;
reg [31:0] ar_dati;
wire [31:0] ar_dato;
reg [31:0] ar_cdato;
reg getset_age;
reg doLoad = 1'b0;
 
/*
initial begin
        for (n = 0; n < ENTRIES; n = n + 1)
        begin
                TLBVirtPage[n] = 0;
                TLBG[n] = 0;
                TLBASID[n] = 0;
                TLBD[n] = 0;
                TLBC[n] = 0;
                TLBA[n] = 0;
                TLBR[n] = 0;
                TLBW[n] = 0;
                TLBX[n] = 0;
                TLBS[n] = 0;
                TLBU[n] = 0;
                TLBValid[n] = 0;
        end
end
*/
 
// Assume the instruction doesn't overlap between a mapped and unmapped area.
wire unmappedArea = vadr_i[ABW-1:ABW-8]==8'hFF || !TLBenabled;
wire m1UnmappedArea = padr_o[ABW-1:ABW-8]==8'hFF || !TLBenabled;
wire hitIOPage = vadr_i[ABW-1:ABW-12]==12'hFFD;
 
always @(posedge clk)
        PageSize <= TLBPageSize[ASID];
 
wire [ABW-1:0] vadrs = vadr_i[ABW-1:13] >> {PageSize,1'b0};
wire [DBW-1:0] TLBPhysPage_rdo;
wire [ABW-1:0] PFN;
 
// Toolset didn't like the simpler distributed code where the RAM was inferred.
// Resulted in combinatorial loop error message. Even though there weren't any
// combinatorial loops.
 
TLBPhysPageRam #(DBW) upgrm1
(
  .clk(clk),
  .we(state==TWO && (op==`TLB_WR || op==`TLB_WI)),
  .wa(i),
  .i(HTLBPhysPage),
  .ra0(i),
  .ra1({q[3:0],vadrs[3:0]}),
  .o0(TLBPhysPage_rdo),
  .o1(PFN)
);
 
wire tlbRo0,tlbRo1;
TLBRam #(1) uR
(
  .clk(clk),
  .we(state==TWO && (op==`TLB_WR || op==`TLB_WI)),
  .wa(i),
  .i(HTLBR),
  .ra0(i),
  .ra1({q[3:0],vadrs[3:0]}),
  .o0(tlbRo0),
  .o1(tlbRo1)
);
 
wire tlbWo0,tlbWo1;
TLBRam #(1) uW
(
  .clk(clk),
  .we(state==TWO && (op==`TLB_WR || op==`TLB_WI)),
  .wa(i),
  .i(HTLBW),
  .ra0(i),
  .ra1({q[3:0],vadrs[3:0]}),
  .o0(tlbWo0),
  .o1(tlbWo1)
);
 
wire tlbXo0,tlbXo1;
TLBRam #(1) uX
(
  .clk(clk),
  .we(state==TWO && (op==`TLB_WR || op==`TLB_WI)),
  .wa(i),
  .i(HTLBX),
  .ra0(i),
  .ra1({q[3:0],vadrs[3:0]}),
  .o0(tlbXo0),
  .o1(tlbXo1)
);
 
always @(posedge clk)
begin
        // age_ctr > age_lmt when counter hits -1, saves comparing to zero as well
        if (age_ctr > age_lmt)
                age_ctr <= age_lmt;
        else
                age_ctr <= age_ctr - 4'd1;
end
 
// Handle Random register
always @(posedge clk)
begin
        if (Random==Wired)
    Random <= 4'hF;
  else
    Random <= Random - 4'd1;
  // Why would we want to update since random changes on the next clock
  // anyways ?
  if (state==ONE) begin
    if (op==`TLB_WRREG && regno==`TLBRandom)
      Random <= dati[3:0];
  end
end
 
always @(posedge clk)
begin
case(state)
IDLE:
        if (ld)
                state <= ONE;
ONE:
        if (op==`TLB_RDAGE || op==`TLB_WRAGE) begin
                if (getset_age)
                        state <= TWO;
        end
        else
                state <= TWO;
TWO:
        state <= IDLE;
default:
        state <= IDLE;
endcase
end
 
// Set index to page table
always @(posedge clk)
if (state==ONE) begin
  case(op)
  `TLB_RD,`TLB_WI:
    i <= {Index[7:4],(HTLBVirtPage >> {HTLBPageSize,1'b0}) & 4'hF};
  `TLB_WR:
    i <= {Random,(HTLBVirtPage >> {HTLBPageSize,1'b0}) & 4'hF};
  endcase
end
 
always @(posedge clk)
begin
        if (miss_addr == {DBW{1'b0}} && TLBMiss)
                miss_addr <= vadr_i;
 
        if (state==ONE) begin
                case(op)
                `TLB_WRREG:
                        begin
                        case(regno)
                        `TLBWired:              Wired <= dati[2:0];
                        `TLBIndex:              Index <= dati[5:0];
                        //`TLBPageSize: PageSize <= dati[2:0];
                        `TLBVirtPage:   HTLBVirtPage <= dati;
                        `TLBPhysPage:   HTLBPhysPage <= dati;
                        `TLBASID:       begin
                                                HTLBValid <= |dati[2:0];
                                                HTLBX <= dati[0];
                                                HTLBW <= dati[1];
                                                HTLBR <= dati[2];
                                                HTLBC <= dati[5:3];
                                                HTLBA <= dati[6];
                                                HTLBS <= dati[7];
                                                HTLBU <= dati[8];
                                                HTLBD <= dati[9];
                                                HTLBG <= dati[10];
                                                HTLBPageSize <= dati[13:11];
                                                HTLBASID <= dati[23:16];
                                                HTLBPL <= dati[31:24];
                                                end
                        `TLBMissAdr:    miss_addr <= dati;
                        `TLBPageTblAddr:        PageTblAddr <= dati;
                        `TLBPageTblCtrl:        PageTblCtrl <= dati;
                        `TLBAFC:        age_lmt <= dati[23:0];
                        default: ;
                        endcase
                        end
                `TLB_EN:
                        TLBenabled <= 1'b1;
                `TLB_DIS:
                        TLBenabled <= 1'b0;
                `TLB_INVALL:
                        TLBValid <= 256'd0;
                default:  ;
                endcase
        end
        else if (state==TWO) begin
                case(op)
                `TLB_P:
                        begin
                                Index[DBW-1] <= ~|Match;
                        end
                `TLB_RD:
                        begin
                                HTLBVirtPage <= TLBVirtPage[i];
                                HTLBPhysPage <= TLBPhysPage_rdo;
                                HTLBASID <= TLBASID[i];
                                HTLBPL <= TLBPL[i];
                                HTLBPageSize <= TLBPageSize[i];
                                HTLBG <= TLBG[i];
                                HTLBD <= TLBD[i];
                                HTLBC <= TLBC[i];
                                HTLBR <= tlbRo0;
                                HTLBW <= tlbWo0;
                                HTLBX <= tlbXo0;
                                HTLBU <= TLBU[i];
                                HTLBS <= TLBS[i];
                                HTLBA <= TLBA[i];
                                HTLBValid <= TLBValid[i];
                        end
                `TLB_WR,`TLB_WI:
                        begin
                                TLBVirtPage[i] <= HTLBVirtPage;
                                TLBASID[i] <= HTLBASID;
                                TLBPL[i] <= HTLBPL;
                                TLBPageSize[i] <= HTLBPageSize;
                                TLBG[i] <= HTLBG;
                                TLBD[i] <= HTLBD;
                                TLBC[i] <= HTLBC;
                                TLBA[i] <= HTLBA;
                                TLBU[i] <= HTLBU;
                                TLBS[i] <= HTLBS;
                                TLBValid[i] <= HTLBValid;
                        end
                default:  ;
                endcase
        end
 
        // Set the dirty bit on a store
        if (we_i)
                if (!m1UnmappedArea & !q[4]) begin
                        TLBD[{q[3:0],vadrs[3:0]}] <= 1'b1;
                end
end
 
always @(posedge clk)
        case(regno)
        `TLBWired:              dato <= Wired;
        `TLBIndex:              dato <= Index;
        `TLBRandom:             dato <= Random;
        `TLBPhysPage:   dato <= HTLBPhysPage;
        `TLBVirtPage:   dato <= HTLBVirtPage;
        `TLBPageSize:   dato <= PageSize;
        `TLBASID:       begin
                                dato <= {DBW{1'b0}};
                                dato[0] <= HTLBX;
                                dato[1] <= HTLBW;
                                dato[2] <= HTLBR;
                                dato[5:3] <= HTLBC;
                                dato[6] <= HTLBA;
                                dato[7] <= HTLBS;
                                dato[8] <= HTLBU;
                                dato[9] <= HTLBD;
                                dato[10] <= HTLBG;
                                dato[13:11] <= HTLBPageSize;
                                dato[23:16] <= HTLBASID;
                                dato[31:24] <= HTLBPL;
                                end
        `TLBMissAdr:    dato <= miss_addr;
        `TLBPageTblAddr:        dato <= PageTblAddr;
        `TLBPageTblCtrl:        dato <= PageTblCtrl;
        `TLBPageCount:          dato <= {16'd0,ar_cdato};
        default:        dato <= {DBW{1'b0}};
        endcase
 
TLBAgeRam uar1(clk,ar_wr,ar_adr,ar_dati,ar_dato);
 
always @(posedge clk)
begin
ar_wr <= 1'b0;
getset_age <= 1'b0;
if (ld)
        doLoad <= 1'b1;
case(ar_state)
IDLE:
        begin
                if (~cyc_i)
                        cyc_en <= 1'b1;
                if (~age_tick)
                        age_en <= 1'b1;
                if ((ld|doLoad) && (op==`TLB_RDAGE || op==`TLB_WRAGE)) begin
                        doLoad <= 1'b0;
                        ar_wr <= op==`TLB_WRAGE;
                        ar_adr <= i;
                        ar_dati <= dati[31:0];
                        ar_state <= READ;
                end
                else if (cyc_i & |Match & cyc_en) begin
                        cyc_en <= 1'b0;
                        ar_adr <= {q[3:0],vadrs[3:0]};
                        ar_state <= INC1;
                end
                else if (age_tick & age_en) begin
                        age_en <= 1'b0;
                        ar_adr <= age_adr;
                        age_adr <= age_adr + 4'd1;
                        ar_state <= AGE1;
                end
        end
READ:
        begin
                getset_age <= 1'b1;
                ar_cdato <= ar_dato;
                ar_state <= IDLE;
        end
INC1:
        begin
                count <= ar_dato;
                ar_state <= INC2;
        end
INC2:
        begin
                count <= {count[31:8] + 4'd1,count[7:0]};
                ar_state <= INC3;
        end
INC3:
        begin
                ar_wr <= 1'b1;
                ar_dati <= {count[32] ? 24'hFFFFFF :count[31:8],count[7:0]};
                ar_state <= IDLE;
        end
AGE1:
        begin
                count <= ar_dato;
                ar_state <= AGE2;
        end
AGE2:
        begin
                ar_wr <= 1'b1;
                ar_dati <= count >> 1;
                ar_state <= IDLE;
        end
endcase
end
 
always @*
for (n = 0; n < 16; n = n + 1)
        Match[n[3:0]] = (vadrs[ABW-1:4]==TLBVirtPage[{n[3:0],vadrs[3:0]}]) &&
                                ((TLBASID[{n[3:0],vadrs[3:0]}]==ASID) || TLBG[{n[3:0],vadrs[3:0]}]) &&
                                TLBValid[{q[3:0],vadrs[3:0]}];
 
always @*
begin
        q = 5'd31;
        for (n = 15; n >= 0; n = n - 1)
                if (Match[n]) q = n;
end
 
assign uncached = TLBC[{q[3:0],vadrs[3:0]}]==3'd1;// || unmappedDataArea;
 
assign TLBMiss = (ol!=2'b00) && TLBenabled && (!unmappedArea & (q[4] | ~TLBValid[{q[3:0],vadrs[3:0]}]) ||
                                        (ol!=2'b00 && hitIOPage));
 
always @(posedge clk)
        cyc_o <= cyc_i && (!TLBMiss || !TLBenabled || (ol == 2'b00));
 
always @(posedge clk)
        we_o <= we_i & ((~TLBMiss & tlbWo1) | ~TLBenabled || (ol==2'b00));
 
always @(posedge clk)
        wrv_o <= we_i & ~TLBMiss & ~tlbWo1 & TLBenabled && (ol != 2'b00);
 
always @(posedge clk)
        rdv_o <= ~we_i & ~TLBMiss & ~tlbRo1 & TLBenabled && (ol != 2'b00);
 
always @(posedge clk)
        exv_o <= icl_i & ~TLBMiss & ~tlbXo1 & TLBenabled && (ol != 2'b00);
 
always @(posedge clk)
if (TLBenabled && ol != 2'b00) begin
        case(PageSize)
        3'd0:   padr_o[ABW-1:13] <=  unmappedArea ? vadr_i[ABW-1:13] : TLBMiss ? `TLBMissPage: PFN;
        3'd1:   padr_o[ABW-1:13] <= {unmappedArea ? vadr_i[ABW-1:15] : TLBMiss ? `TLBMissPage: PFN,vadr_i[14:13]};
        3'd2:   padr_o[ABW-1:13] <= {unmappedArea ? vadr_i[ABW-1:17] : TLBMiss ? `TLBMissPage: PFN,vadr_i[16:13]};
        3'd3:   padr_o[ABW-1:13] <= {unmappedArea ? vadr_i[ABW-1:19] : TLBMiss ? `TLBMissPage: PFN,vadr_i[18:13]};
        3'd4:   padr_o[ABW-1:13] <= {unmappedArea ? vadr_i[ABW-1:21] : TLBMiss ? `TLBMissPage: PFN,vadr_i[20:13]};
        3'd5:   padr_o[ABW-1:13] <= {unmappedArea ? vadr_i[ABW-1:23] : TLBMiss ? `TLBMissPage: PFN,vadr_i[22:13]};
        default:        padr_o[ABW-1:13] <= vadr_i[ABW-1:13];
        endcase
        padr_o[12:0] <= vadr_i[12:0];
end
else
        padr_o <= vadr_i;
 
endmodule
 
module TLBRam(clk,we,wa,i,ra0,ra1,o0,o1);
parameter DBW=1;
input clk;
input we;
input [7:0] wa;
input [DBW-1:0] i;
input [7:0] ra0;
input [7:0] ra1;
output [DBW-1:0] o0;
output [DBW-1:0] o1;
 
reg [DBW-1:0] mem [0:255];
 
always @(posedge clk)
  if (we)
    mem[wa] <= i;
 
assign o0 = mem[ra0];
assign o1 = mem[ra1];
 
endmodule
 
module TLBPhysPageRam(clk,we,wa,i,ra0,ra1,o0,o1);
parameter DBW=64;
input clk;
input we;
input [7:0] wa;
input [DBW-1:0] i;
input [7:0] ra0;
input [7:0] ra1;
output [DBW-1:0] o0;
output [DBW-1:0] o1;
 
reg [DBW-1:0] mem [0:255];
 
always @(posedge clk)
  if (we)
    mem[wa] <= i;
 
assign o0 = mem[ra0];
assign o1 = mem[ra1];
 
endmodule
 
module TLBAgeRam(clk,we,a,i,o);
parameter DBW=32;
input clk;
input we;
input [7:0] a;
input [DBW-1:0] i;
output [DBW-1:0] o;
 
reg [DBW-1:0] mem [0:255];
 
always @(posedge clk)
  if (we)
    mem[a] <= i;
 
assign o = mem[a];
 
endmodule
 

Line No.	Rev	Author	Line
1	60	robfinch	`include "FT64_defines.vh"
2			`include "FT64_config.vh"
3			`//=============================================================================`
4			`// __`
5	66	robfinch	`// \\__/ o\ (C) 2011-2019 Robert Finch, Waterloo`
6	60	robfinch	`// \ __ / All rights reserved.`
7			`// \/_// robfinch<remove>@finitron.ca`
8			`// \|\|`
9			`//`
10			`// FT64_TLB.v`
11			`//`
12			`//`
13			`// This source file is free software: you can redistribute it and/or modify`
14			`// it under the terms of the GNU Lesser General Public License as published`
15			`// by the Free Software Foundation, either version 3 of the License, or`
16			`// (at your option) any later version.`
17			`//`
18			`// This source file is distributed in the hope that it will be useful,`
19			`// but WITHOUT ANY WARRANTY; without even the implied warranty of`
20			`// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the`
21			`// GNU General Public License for more details.`
22			`//`
23			`// You should have received a copy of the GNU General Public License`
24			`// along with this program. If not, see <http://www.gnu.org/licenses/>.`
25			`//`
26			`//`
27			`// TLB`
28			`// The TLB contains 256 entries, that are 16 way set associative.`
29			`// The TLB is shared between the instruction and data streams.`
30	66	robfinch	`// The code is carefully constructed to not require reset signals.`
31	60	robfinch	`//`
32			`//=============================================================================`
33			`//`
34			`define TLBMissPage {DBW-13{1'b1}}
35
36	66	robfinch	`module FT64_TLB(clk, ld, done, idle, ol,`
37	60	robfinch	`ASID, op, regno, dati, dato,`
38			`uncached,`
39			`icl_i, cyc_i, we_i, vadr_i, cyc_o, we_o, padr_o,`
40			`wrv_o, rdv_o, exv_o,`
41			`TLBMiss, HTLBVirtPageo);`
42			`parameter DBW=64;`
43			`parameter ABW=32;`
44			`parameter ENTRIES=256;`
45			`parameter IDLE = 4'd0;`
46			`parameter ONE = 4'd1;`
47			`parameter TWO = 4'd2;`
48			`parameter READ = 4'd1;`
49			`parameter INC1 = 4'd2;`
50			`parameter INC2 = 4'd3;`
51			`parameter INC3 = 4'd4;`
52			`parameter AGE1 = 4'd5;`
53			`parameter AGE2 = 4'd6;`
54			`input clk;`
55			`input ld;`
56			`output done;`
57			`output idle;`
58			`input [1:0] ol; // operating level`
59			`input [ABW-1:0] vadr_i;`
60	66	robfinch	`output reg [ABW-1:0] padr_o = 64'hFFFFFFFFFFFC0100;`
61	60	robfinch	`output uncached;`
62
63			`input icl_i;`
64			`input cyc_i;`
65			`input we_i;`
66			`output reg cyc_o;`
67			`output reg we_o;`
68			`output reg exv_o;`
69			`output reg wrv_o;`
70			`output reg rdv_o;`
71			`input [7:0] ASID;`
72			`input [3:0] op;`
73			`input [3:0] regno;`
74			`input [DBW-1:0] dati;`
75			`output reg [DBW-1:0] dato;`
76			`output TLBMiss;`
77			`output [DBW-1:0] HTLBVirtPageo;`
78
79			`integer n;`
80
81	66	robfinch	`reg [1:0] state = IDLE;`
82	60	robfinch	`assign done = state==(IDLE && !ld) \|\| state==TWO;`
83			`assign idle = state==IDLE && !ld;`
84
85			`// Holding registers`
86			`// These allow the TLB to updated in a single cycle as a unit`
87			`reg [DBW-1:0] HTLBVirtPage;`
88			`assign HTLBVirtPageo = {HTLBVirtPage,13'b0};`
89			`reg [DBW-1:0] HTLBPhysPage;`
90			`reg [7:0] HTLBASID;`
91			`reg HTLBG;`
92			`reg HTLBD;`
93			`reg HTLBR, HTLBW, HTLBX, HTLBA, HTLBU, HTLBS;`
94			`reg [2:0] HTLBC;`
95			`reg [7:0] HTLBPL;`
96			`reg [2:0] HTLBPageSize;`
97			`reg HTLBValid;`
98			`reg [ABW-1:0] miss_addr;`
99
100	66	robfinch	`reg TLBenabled = 1'b0;`
101			`reg [7:0] i = 8'h00;`
102	60	robfinch	`reg [DBW-1:0] Index;`
103	66	robfinch	`reg [3:0] Random = 4'hF;`
104			`reg [3:0] Wired = 4'd0;`
105	60	robfinch	`reg [2:0] PageSize;`
106			`reg [15:0] Match;`
107
108			`reg [4:0] q;`
109			`wire doddpage;`
110			`reg [DBW-1:0] TLBVirtPage [ENTRIES-1:0];`
111			`reg [ENTRIES-1:0] TLBG;`
112			`reg [ENTRIES-1:0] TLBD;`
113			`reg [ENTRIES-1:0] TLBU;`
114			`reg [ENTRIES-1:0] TLBS;`
115			`reg [ENTRIES-1:0] TLBA;`
116			`reg [2:0] TLBC [ENTRIES-1:0];`
117			`reg [7:0] TLBASID [ENTRIES-1:0];`
118			`reg [7:0] TLBPL [ENTRIES-1:0];`
119			`reg [2:0] TLBPageSize [255:0];`
120			`reg [ENTRIES-1:0] TLBValid;`
121			`reg [DBW-1:0] imiss_addr;`
122			`reg [DBW-1:0] dmiss_addr;`
123	66	robfinch	`reg [DBW-1:0] PageTblAddr = {DBW{1'b0}};`
124			`reg [DBW-1:0] PageTblCtrl = {DBW{1'b0}};`
125	60	robfinch
126	66	robfinch	`reg [23:0] age_lmt = 24'd20000;`
127			`reg [23:0] age_ctr = 24'd0;`
128	60	robfinch	`wire age_tick = age_ctr < 24'd5;`
129	66	robfinch	`reg cyc_en = 1'b1, age_en = 1'b1;`
130			`reg [3:0] ar_state = IDLE;`
131			`reg ar_wr = 1'b0;`
132			`reg [7:0] age_adr = 8'h00, ar_adr = 8'h00;`
133	60	robfinch	`reg [32:0] count;`
134			`reg [31:0] ar_dati;`
135			`wire [31:0] ar_dato;`
136			`reg [31:0] ar_cdato;`
137			`reg getset_age;`
138	66	robfinch	`reg doLoad = 1'b0;`
139	60	robfinch
140			`/*`
141			`initial begin`
142			`for (n = 0; n < ENTRIES; n = n + 1)`
143			`begin`
144			`TLBVirtPage[n] = 0;`
145			`TLBG[n] = 0;`
146			`TLBASID[n] = 0;`
147			`TLBD[n] = 0;`
148			`TLBC[n] = 0;`
149			`TLBA[n] = 0;`
150			`TLBR[n] = 0;`
151			`TLBW[n] = 0;`
152			`TLBX[n] = 0;`
153			`TLBS[n] = 0;`
154			`TLBU[n] = 0;`
155			`TLBValid[n] = 0;`
156			`end`
157			`end`
158			`*/`
159
160			`// Assume the instruction doesn't overlap between a mapped and unmapped area.`
161			`wire unmappedArea = vadr_i[ABW-1:ABW-8]==8'hFF \|\| !TLBenabled;`
162			`wire m1UnmappedArea = padr_o[ABW-1:ABW-8]==8'hFF \|\| !TLBenabled;`
163			`wire hitIOPage = vadr_i[ABW-1:ABW-12]==12'hFFD;`
164
165			`always @(posedge clk)`
166			`PageSize <= TLBPageSize[ASID];`
167
168			`wire [ABW-1:0] vadrs = vadr_i[ABW-1:13] >> {PageSize,1'b0};`
169			`wire [DBW-1:0] TLBPhysPage_rdo;`
170			`wire [ABW-1:0] PFN;`
171
172			`// Toolset didn't like the simpler distributed code where the RAM was inferred.`
173			`// Resulted in combinatorial loop error message. Even though there weren't any`
174			`// combinatorial loops.`
175
176			`TLBPhysPageRam #(DBW) upgrm1`
177			`(`
178			`.clk(clk),`
179			.we(state==TWO && (op==`TLB_WR \|\| op==`TLB_WI)),
180			`.wa(i),`
181			`.i(HTLBPhysPage),`
182			`.ra0(i),`
183			`.ra1({q[3:0],vadrs[3:0]}),`
184			`.o0(TLBPhysPage_rdo),`
185			`.o1(PFN)`
186			`);`
187
188			`wire tlbRo0,tlbRo1;`
189			`TLBRam #(1) uR`
190			`(`
191			`.clk(clk),`
192			.we(state==TWO && (op==`TLB_WR \|\| op==`TLB_WI)),
193			`.wa(i),`
194			`.i(HTLBR),`
195			`.ra0(i),`
196			`.ra1({q[3:0],vadrs[3:0]}),`
197			`.o0(tlbRo0),`
198			`.o1(tlbRo1)`
199			`);`
200
201			`wire tlbWo0,tlbWo1;`
202			`TLBRam #(1) uW`
203			`(`
204			`.clk(clk),`
205			.we(state==TWO && (op==`TLB_WR \|\| op==`TLB_WI)),
206			`.wa(i),`
207			`.i(HTLBW),`
208			`.ra0(i),`
209			`.ra1({q[3:0],vadrs[3:0]}),`
210			`.o0(tlbWo0),`
211			`.o1(tlbWo1)`
212			`);`
213
214			`wire tlbXo0,tlbXo1;`
215			`TLBRam #(1) uX`
216			`(`
217			`.clk(clk),`
218			.we(state==TWO && (op==`TLB_WR \|\| op==`TLB_WI)),
219			`.wa(i),`
220			`.i(HTLBX),`
221			`.ra0(i),`
222			`.ra1({q[3:0],vadrs[3:0]}),`
223			`.o0(tlbXo0),`
224			`.o1(tlbXo1)`
225			`);`
226
227			`always @(posedge clk)`
228	66	robfinch	`begin`
229			`// age_ctr > age_lmt when counter hits -1, saves comparing to zero as well`
230			`if (age_ctr > age_lmt)`
231	60	robfinch	`age_ctr <= age_lmt;`
232			`else`
233			`age_ctr <= age_ctr - 4'd1;`
234			`end`
235
236			`// Handle Random register`
237			`always @(posedge clk)`
238	66	robfinch	`begin`
239	60	robfinch	`if (Random==Wired)`
240			`Random <= 4'hF;`
241			`else`
242			`Random <= Random - 4'd1;`
243			`// Why would we want to update since random changes on the next clock`
244			`// anyways ?`
245			`if (state==ONE) begin`
246			if (op==`TLB_WRREG && regno==`TLBRandom)
247			`Random <= dati[3:0];`
248			`end`
249			`end`
250
251			`always @(posedge clk)`
252	66	robfinch	`begin`
253	60	robfinch	`case(state)`
254			`IDLE:`
255			`if (ld)`
256			`state <= ONE;`
257			`ONE:`
258			if (op==`TLB_RDAGE \|\| op==`TLB_WRAGE) begin
259			`if (getset_age)`
260			`state <= TWO;`
261			`end`
262			`else`
263			`state <= TWO;`
264			`TWO:`
265			`state <= IDLE;`
266			`default:`
267			`state <= IDLE;`
268			`endcase`
269			`end`
270
271			`// Set index to page table`
272			`always @(posedge clk)`
273	66	robfinch	`if (state==ONE) begin`
274			`case(op)`
275			`TLB_RD,`TLB_WI:
276			`i <= {Index[7:4],(HTLBVirtPage >> {HTLBPageSize,1'b0}) & 4'hF};`
277			`TLB_WR:
278			`i <= {Random,(HTLBVirtPage >> {HTLBPageSize,1'b0}) & 4'hF};`
279			`endcase`
280	60	robfinch	`end`
281
282			`always @(posedge clk)`
283	66	robfinch	`begin`
284	60	robfinch	`if (miss_addr == {DBW{1'b0}} && TLBMiss)`
285			`miss_addr <= vadr_i;`
286
287			`if (state==ONE) begin`
288			`case(op)`
289			`TLB_WRREG:
290			`begin`
291			`case(regno)`
292			`TLBWired: Wired <= dati[2:0];
293			`TLBIndex: Index <= dati[5:0];
294			//`TLBPageSize: PageSize <= dati[2:0];
295			`TLBVirtPage: HTLBVirtPage <= dati;
296			`TLBPhysPage: HTLBPhysPage <= dati;
297			`TLBASID: begin
298			`HTLBValid <= \|dati[2:0];`
299			`HTLBX <= dati[0];`
300			`HTLBW <= dati[1];`
301			`HTLBR <= dati[2];`
302			`HTLBC <= dati[5:3];`
303			`HTLBA <= dati[6];`
304			`HTLBS <= dati[7];`
305			`HTLBU <= dati[8];`
306			`HTLBD <= dati[9];`
307			`HTLBG <= dati[10];`
308			`HTLBPageSize <= dati[13:11];`
309			`HTLBASID <= dati[23:16];`
310			`HTLBPL <= dati[31:24];`
311			`end`
312			`TLBMissAdr: miss_addr <= dati;
313			`TLBPageTblAddr: PageTblAddr <= dati;
314			`TLBPageTblCtrl: PageTblCtrl <= dati;
315			`TLBAFC: age_lmt <= dati[23:0];
316			`default: ;`
317			`endcase`
318			`end`
319			`TLB_EN:
320			`TLBenabled <= 1'b1;`
321			`TLB_DIS:
322			`TLBenabled <= 1'b0;`
323			`TLB_INVALL:
324			`TLBValid <= 256'd0;`
325			`default: ;`
326			`endcase`
327			`end`
328			`else if (state==TWO) begin`
329			`case(op)`
330			`TLB_P:
331			`begin`
332			`Index[DBW-1] <= ~\|Match;`
333			`end`
334			`TLB_RD:
335			`begin`
336			`HTLBVirtPage <= TLBVirtPage[i];`
337			`HTLBPhysPage <= TLBPhysPage_rdo;`
338			`HTLBASID <= TLBASID[i];`
339			`HTLBPL <= TLBPL[i];`
340			`HTLBPageSize <= TLBPageSize[i];`
341			`HTLBG <= TLBG[i];`
342			`HTLBD <= TLBD[i];`
343			`HTLBC <= TLBC[i];`
344			`HTLBR <= tlbRo0;`
345			`HTLBW <= tlbWo0;`
346			`HTLBX <= tlbXo0;`
347			`HTLBU <= TLBU[i];`
348			`HTLBS <= TLBS[i];`
349			`HTLBA <= TLBA[i];`
350			`HTLBValid <= TLBValid[i];`
351			`end`
352			`TLB_WR,`TLB_WI:
353			`begin`
354			`TLBVirtPage[i] <= HTLBVirtPage;`
355			`TLBASID[i] <= HTLBASID;`
356			`TLBPL[i] <= HTLBPL;`
357			`TLBPageSize[i] <= HTLBPageSize;`
358			`TLBG[i] <= HTLBG;`
359			`TLBD[i] <= HTLBD;`
360			`TLBC[i] <= HTLBC;`
361			`TLBA[i] <= HTLBA;`
362			`TLBU[i] <= HTLBU;`
363			`TLBS[i] <= HTLBS;`
364			`TLBValid[i] <= HTLBValid;`
365			`end`
366			`default: ;`
367			`endcase`
368			`end`
369
370			`// Set the dirty bit on a store`
371			`if (we_i)`
372			`if (!m1UnmappedArea & !q[4]) begin`
373			`TLBD[{q[3:0],vadrs[3:0]}] <= 1'b1;`
374			`end`
375			`end`
376
377			`always @(posedge clk)`
378			`case(regno)`
379			`TLBWired: dato <= Wired;
380			`TLBIndex: dato <= Index;
381			`TLBRandom: dato <= Random;
382			`TLBPhysPage: dato <= HTLBPhysPage;
383			`TLBVirtPage: dato <= HTLBVirtPage;
384			`TLBPageSize: dato <= PageSize;
385			`TLBASID: begin
386			`dato <= {DBW{1'b0}};`
387			`dato[0] <= HTLBX;`
388			`dato[1] <= HTLBW;`
389			`dato[2] <= HTLBR;`
390			`dato[5:3] <= HTLBC;`
391			`dato[6] <= HTLBA;`
392			`dato[7] <= HTLBS;`
393			`dato[8] <= HTLBU;`
394			`dato[9] <= HTLBD;`
395			`dato[10] <= HTLBG;`
396			`dato[13:11] <= HTLBPageSize;`
397			`dato[23:16] <= HTLBASID;`
398			`dato[31:24] <= HTLBPL;`
399			`end`
400			`TLBMissAdr: dato <= miss_addr;
401			`TLBPageTblAddr: dato <= PageTblAddr;
402			`TLBPageTblCtrl: dato <= PageTblCtrl;
403			`TLBPageCount: dato <= {16'd0,ar_cdato};
404			`default: dato <= {DBW{1'b0}};`
405			`endcase`
406
407			`TLBAgeRam uar1(clk,ar_wr,ar_adr,ar_dati,ar_dato);`
408
409			`always @(posedge clk)`
410	66	robfinch	`begin`
411	60	robfinch	`ar_wr <= 1'b0;`
412			`getset_age <= 1'b0;`
413			`if (ld)`
414			`doLoad <= 1'b1;`
415			`case(ar_state)`
416			`IDLE:`
417			`begin`
418			`if (~cyc_i)`
419			`cyc_en <= 1'b1;`
420			`if (~age_tick)`
421			`age_en <= 1'b1;`
422			if ((ld\|doLoad) && (op==`TLB_RDAGE \|\| op==`TLB_WRAGE)) begin
423			`doLoad <= 1'b0;`
424			ar_wr <= op==`TLB_WRAGE;
425			`ar_adr <= i;`
426			`ar_dati <= dati[31:0];`
427			`ar_state <= READ;`
428			`end`
429			`else if (cyc_i & \|Match & cyc_en) begin`
430			`cyc_en <= 1'b0;`
431			`ar_adr <= {q[3:0],vadrs[3:0]};`
432			`ar_state <= INC1;`
433			`end`
434			`else if (age_tick & age_en) begin`
435			`age_en <= 1'b0;`
436			`ar_adr <= age_adr;`
437			`age_adr <= age_adr + 4'd1;`
438			`ar_state <= AGE1;`
439			`end`
440			`end`
441			`READ:`
442			`begin`
443			`getset_age <= 1'b1;`
444			`ar_cdato <= ar_dato;`
445			`ar_state <= IDLE;`
446			`end`
447			`INC1:`
448			`begin`
449			`count <= ar_dato;`
450			`ar_state <= INC2;`
451			`end`
452			`INC2:`
453			`begin`
454			`count <= {count[31:8] + 4'd1,count[7:0]};`
455			`ar_state <= INC3;`
456			`end`
457			`INC3:`
458			`begin`
459			`ar_wr <= 1'b1;`
460			`ar_dati <= {count[32] ? 24'hFFFFFF :count[31:8],count[7:0]};`
461			`ar_state <= IDLE;`
462			`end`
463			`AGE1:`
464			`begin`
465			`count <= ar_dato;`
466			`ar_state <= AGE2;`
467			`end`
468			`AGE2:`
469			`begin`
470			`ar_wr <= 1'b1;`
471			`ar_dati <= count >> 1;`
472			`ar_state <= IDLE;`
473			`end`
474			`endcase`
475			`end`
476
477			`always @*`
478			`for (n = 0; n < 16; n = n + 1)`
479			`Match[n[3:0]] = (vadrs[ABW-1:4]==TLBVirtPage[{n[3:0],vadrs[3:0]}]) &&`
480			`((TLBASID[{n[3:0],vadrs[3:0]}]==ASID) \|\| TLBG[{n[3:0],vadrs[3:0]}]) &&`
481			`TLBValid[{q[3:0],vadrs[3:0]}];`
482
483			`always @*`
484			`begin`
485			`q = 5'd31;`
486			`for (n = 15; n >= 0; n = n - 1)`
487			`if (Match[n]) q = n;`
488			`end`
489
490			`assign uncached = TLBC[{q[3:0],vadrs[3:0]}]==3'd1;// \|\| unmappedDataArea;`
491
492	66	robfinch	`assign TLBMiss = (ol!=2'b00) && TLBenabled && (!unmappedArea & (q[4] \| ~TLBValid[{q[3:0],vadrs[3:0]}]) \|\|`
493	60	robfinch	`(ol!=2'b00 && hitIOPage));`
494
495			`always @(posedge clk)`
496	66	robfinch	`cyc_o <= cyc_i && (!TLBMiss \|\| !TLBenabled \|\| (ol == 2'b00));`
497	60	robfinch
498			`always @(posedge clk)`
499	66	robfinch	`we_o <= we_i & ((~TLBMiss & tlbWo1) \| ~TLBenabled \|\| (ol==2'b00));`
500	60	robfinch

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