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// ============================================================================

//        __

//   \\__/ o\    (C) 2017-2018  Robert Finch, Waterloo

//    \  __ /    All rights reserved.

//     \/_//     robfinch<remove>@finitron.ca

//       ||

//

//      FT64_cache.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/>.    

//                                                                          

//

// ============================================================================

//

`define TRUE    1'b1

`define FALSE   1'b0

`define BRK         6'd0

`define FLT_EXF     9'd497

`define FLT_IBE     9'd509

// -----------------------------------------------------------------------------

// Small, 64 line cache memory (2kiB) made from distributed RAM. Access is

// within a single clock cycle.

// -----------------------------------------------------------------------------

module FT64_L1_icache_mem(rst, clk, wr, en, lineno, i, o, ov, invall, invline);

parameter pLines = 64;

parameter pLineWidth = 288;

input rst;

input clk;

input wr;

input [8:0] en;

input [5:0] lineno;

input [pLineWidth-1:0] i;

output [pLineWidth-1:0] o;

output [8:0] ov;

input invall;

input invline;

(* ram_style="distributed" *)

reg [pLineWidth-1:0] mem [0:pLines-1];

reg [pLines-1:0] valid0;

reg [pLines-1:0] valid1;

reg [pLines-1:0] valid2;

reg [pLines-1:0] valid3;

reg [pLines-1:0] valid4;

reg [pLines-1:0] valid5;

reg [pLines-1:0] valid6;

reg [pLines-1:0] valid7;

reg [pLines-1:0] valid8;

always  @(posedge clk)

    if (wr & en[0])  mem[lineno][31:0] <= i[31:0];

always  @(posedge clk)

    if (wr & en[1])  mem[lineno][63:32] <= i[63:32];

always  @(posedge clk)

    if (wr & en[2])  mem[lineno][95:64] <= i[95:64];

always  @(posedge clk)

    if (wr & en[3])  mem[lineno][127:96] <= i[127:96];

always  @(posedge clk)

    if (wr & en[4])  mem[lineno][159:128] <= i[159:128];

always  @(posedge clk)

    if (wr & en[5])  mem[lineno][191:160] <= i[191:160];

always  @(posedge clk)

    if (wr & en[6])  mem[lineno][223:192] <= i[223:192];

always  @(posedge clk)

    if (wr & en[7])  mem[lineno][255:224] <= i[255:224];

always  @(posedge clk)

    if (wr & en[8])  mem[lineno][287:256] <= i[287:256];

always  @(posedge clk)

if (rst) begin

     valid0 <= 64'd0;

     valid1 <= 64'd0;

     valid2 <= 64'd0;

     valid3 <= 64'd0;

     valid4 <= 64'd0;

     valid5 <= 64'd0;

     valid6 <= 64'd0;

     valid7 <= 64'd0;

     valid8 <= 64'd0;

end

else begin

    if (invall) begin

        valid0 <= 64'd0;

        valid1 <= 64'd0;

        valid2 <= 64'd0;

        valid3 <= 64'd0;

        valid4 <= 64'd0;

        valid5 <= 64'd0;

        valid6 <= 64'd0;

        valid7 <= 64'd0;

                        valid8 <= 64'd0;

    end

    else if (invline) begin

        valid0[lineno] <= 1'b0;

        valid1[lineno] <= 1'b0;

        valid2[lineno] <= 1'b0;

        valid3[lineno] <= 1'b0;

        valid4[lineno] <= 1'b0;

        valid5[lineno] <= 1'b0;

        valid6[lineno] <= 1'b0;

        valid7[lineno] <= 1'b0;

        valid8[lineno] <= 1'b0;

        end

    else if (wr) begin

        if (en[0]) valid0[lineno] <= 1'b1;

        if (en[1]) valid1[lineno] <= 1'b1;

        if (en[2]) valid2[lineno] <= 1'b1;

        if (en[3]) valid3[lineno] <= 1'b1;

        if (en[4]) valid4[lineno] <= 1'b1;

        if (en[5]) valid5[lineno] <= 1'b1;

        if (en[6]) valid6[lineno] <= 1'b1;

        if (en[7]) valid7[lineno] <= 1'b1;

        if (en[8]) valid8[lineno] <= 1'b1;

    end

end

assign o = mem[lineno];

assign ov[0] = valid0[lineno];

assign ov[1] = valid1[lineno];

assign ov[2] = valid2[lineno];

assign ov[3] = valid3[lineno];

assign ov[4] = valid4[lineno];

assign ov[5] = valid5[lineno];

assign ov[6] = valid6[lineno];

assign ov[7] = valid7[lineno];

assign ov[8] = valid8[lineno];

endmodule

// -----------------------------------------------------------------------------

// Fully associative (64 way) tag memory for L1 icache.

//

// -----------------------------------------------------------------------------

module FT64_L1_icache_camtag(rst, clk, nxt, wlineno, wr, wadr, adr, hit, lineno);

input rst;

input clk;

input nxt;

output [5:0] wlineno;

input wr;

input [37:0] adr;

input [37:0] wadr;

output hit;

output reg [5:0] lineno;

wire [35:0] wtagi = {9'b0,wadr[37:5]};

wire [35:0] tagi = {9'b0,adr[37:5]};

wire [63:0] match_addr;

reg [5:0] cntr;

always @(posedge clk)

if (rst)

     cntr <= 6'd0;

else begin

    if (nxt)  cntr <= cntr + 6'd1;

end

assign wlineno = cntr;

//wire [21:0] lfsro;

//lfsr #(22,22'h0ACE1) u1 (rst, clk, !(wr3|wr2|wr), 1'b0, lfsro);

cam36x64 u01 (rst, clk, wr, cntr[5:0], wtagi, tagi, match_addr);

assign hit = |match_addr;

integer n;

always @*

begin

lineno = 0;

for (n = 0; n < 64; n = n + 1)

    if (match_addr[n]) lineno = n;

end

endmodule

// -----------------------------------------------------------------------------

// Four way set associative tag memory for L1 cache.

// -----------------------------------------------------------------------------

module FT64_L1_icache_cmptag4way(rst, clk, nxt, wr, adr, lineno, hit);

input rst;

input clk;

input nxt;

input wr;

input [37:0] adr;

output reg [5:0] lineno;

output hit;

(* ram_style="distributed" *)

reg [32:0] mem0 [0:15];

reg [32:0] mem1 [0:15];

reg [32:0] mem2 [0:15];

reg [32:0] mem3 [0:15];

reg [37:0] rradr;

integer n;

initial begin

    for (n = 0; n < 16; n = n + 1)

    begin

        mem0[n] = 0;

        mem1[n] = 0;

        mem2[n] = 0;

        mem3[n] = 0;

    end

end

wire [21:0] lfsro;

lfsr #(22,22'h0ACE3) u1 (rst, clk, nxt, 1'b0, lfsro);

reg [5:0] wlineno;

always @(posedge clk)

if (rst)

        wlineno <= 6'h00;

else begin

        if (wr) begin

                case(lfsro[1:0])

                2'b00:  begin  mem0[adr[8:5]] <= adr[37:5];  wlineno <= {2'b00,adr[8:5]}; end

                2'b01:  begin  mem1[adr[8:5]] <= adr[37:5];  wlineno <= {2'b01,adr[8:5]}; end

                2'b10:  begin  mem2[adr[8:5]] <= adr[37:5];  wlineno <= {2'b10,adr[8:5]}; end

                2'b11:  begin  mem3[adr[8:5]] <= adr[37:5];  wlineno <= {2'b11,adr[8:5]}; end

                endcase

        end

end

wire hit0 = mem0[adr[8:5]]==adr[37:5];

wire hit1 = mem1[adr[8:5]]==adr[37:5];

wire hit2 = mem2[adr[8:5]]==adr[37:5];

wire hit3 = mem3[adr[8:5]]==adr[37:5];

always @*

    //if (wr2) lineno = wlineno;

    if (hit0)  lineno = {2'b00,adr[8:5]};

    else if (hit1)  lineno = {2'b01,adr[8:5]};

    else if (hit2)  lineno = {2'b10,adr[8:5]};

    else  lineno = {2'b11,adr[8:5]};

assign hit = hit0|hit1|hit2|hit3;

endmodule

// -----------------------------------------------------------------------------

// 32 way, 16 set associative tag memory for L2 cache

// -----------------------------------------------------------------------------

module FT64_L2_icache_camtag(rst, clk, wr, adr, hit, lineno);

input rst;

input clk;

input wr;

input [37:0] adr;

output hit;

output [8:0] lineno;

wire [3:0] set = adr[13:10];

wire [35:0] tagi = {7'd0,adr[37:14],adr[9:5]};

reg [4:0] encadr;

assign lineno[4:0] = encadr;

assign lineno[8:5] = adr[13:10];

reg [15:0] we;

wire [31:0] ma [0:15];

always @*

begin

    we <= 16'h0000;

    we[set] <= wr;

end

reg wr2;

wire [21:0] lfsro;

lfsr #(22,22'h0ACE2) u1 (rst, clk, !(wr2|wr), 1'b0, lfsro);

always @(posedge clk)

     wr2 <= wr;

genvar g;

generate

begin

for (g = 0; g < 16; g = g + 1)

    cam36x32 u01 (clk, we[g], lfsro[4:0], tagi, tagi, ma[g]);

end

endgenerate

wire [31:0] match_addr = ma[set];

assign hit = |match_addr;

integer n;

always @*

begin

encadr = 0;

for (n = 0; n < 32; n = n + 1)

    if (match_addr[n]) encadr = n;

end

endmodule

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

module FT64_L1_icache(rst, clk, nxt, wr, wr_ack, en, wadr, adr, i, o, hit, invall, invline);

parameter CAMTAGS = 1'b0;   // 32 way

parameter FOURWAY = 1'b1;

input rst;

input clk;

input nxt;

input wr;

output wr_ack;

input [8:0] en;

input [37:0] adr;

input [37:0] wadr;

input [287:0] i;

output reg [47:0] o;

output hit;

input invall;

input invline;

wire [287:0] ic;

reg [287:0] i1, i2;

wire [8:0] lv;                           // line valid

wire [5:0] lineno;

wire [5:0] wlineno;

wire taghit;

reg wr1,wr2;

reg [8:0] en1, en2;

reg invline1, invline2;

// Must update the cache memory on the cycle after a write to the tag memmory.

// Otherwise lineno won't be valid. Tag memory takes two clock cycles to update.

always @(posedge clk)

        wr1 <= wr;

always @(posedge clk)

        wr2 <= wr1;

always @(posedge clk)

        i1 <= i[287:0];

always @(posedge clk)

        i2 <= i1;

always @(posedge clk)

        en1 <= en;

always @(posedge clk)

        en2 <= en1;

always @(posedge clk)

        invline1 <= invline;

always @(posedge clk)

        invline2 <= invline1;

generate begin : tags

if (FOURWAY) begin

FT64_L1_icache_mem u1

(

    .rst(rst),

    .clk(clk),

    .wr(wr1),

    .en(en1),

    .i(i1),

    .lineno(lineno),

    .o(ic),

    .ov(lv),

    .invall(invall),

    .invline(invline1)

);

FT64_L1_icache_cmptag4way u3

(

        .rst(rst),

        .clk(clk),

        .nxt(nxt),

        .wr(wr),

        .adr(adr),

        .lineno(lineno),

        .hit(taghit)

);

end

else if (CAMTAGS) begin

FT64_L1_icache_mem u1

(

    .rst(rst),

    .clk(clk),

    .wr(wr2),

    .en(en2),

    .i(i2),

    .lineno(lineno),

    .o(ic),

    .ov(lv),

    .invall(invall),

    .invline(invline2)

);

FT64_L1_icache_camtag u2

(

    .rst(rst),

    .clk(clk),

    .nxt(nxt),

    .wlineno(wlineno),

    .wadr(wadr),

    .wr(wr),

    .adr(adr),

    .lineno(lineno),

    .hit(taghit)

);

end

end

endgenerate

// Valid if a 64-bit area encompassing a potential 48-bit instruction is valid.

assign hit = taghit & lv[adr[4:2]] & lv[adr[4:2]+4'd1];

//always @(radr or ic0 or ic1)

always @(adr or ic)

        o <= ic >> {adr[4:1],4'h0};

assign wr_ack = wr2;

endmodule

// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------

module FT64_L2_icache_mem(clk, wr, lineno, sel, i, o, ov, invall, invline);

input clk;

input wr;

input [8:0] lineno;

input [2:0] sel;

input [63:0] i;

output [287:0] o;

output reg ov;

input invall;

input invline;

(* ram_style="block" *)

reg [63:0] mem0 [0:511];

reg [63:0] mem1 [0:511];

reg [63:0] mem2 [0:511];

reg [63:0] mem3 [0:511];

reg [31:0] mem4 [0:511];

reg [511:0] valid;

reg [8:0] rrcl;

//  instruction parcels per cache line

wire [8:0] cache_line;

integer n;

initial begin

    for (n = 0; n < 512; n = n + 1)

        valid[n] <= 0;

end

always @(posedge clk)

    if (invall)  valid <= 512'd0;

    else if (invline)  valid[lineno] <= 1'b0;

    else if (wr)  valid[lineno] <= 1'b1;

always @(posedge clk)

begin

    if (wr) begin

        case(sel[2:0])

        3'd0:    mem0[lineno] <= i;

        3'd1:    mem1[lineno] <= i;

        3'd2:    mem2[lineno] <= i;

        3'd3:    mem3[lineno] <= i;

        3'd4:    mem4[lineno] <= i[31:0];

        endcase

    end

end

always @(posedge clk)

     rrcl <= lineno;

always @(posedge clk)

     ov <= valid[lineno];

assign o = {mem4[rrcl],mem3[rrcl],mem2[rrcl],mem1[rrcl],mem0[rrcl]};

endmodule

// -----------------------------------------------------------------------------

// Because the line to update is driven by the output of the cam tag memory,

// the tag write should occur only during the first half of the line load.

// Otherwise the line number would change in the middle of the line. The

// first half of the line load is signified by an even hexibyte address (

// address bit 4).

// -----------------------------------------------------------------------------

module FT64_L2_icache(rst, clk, nxt, wr, wr_ack, rd_ack, xsel, adr, cnt, exv_i, i, err_i, o, hit, invall, invline);

parameter CAMTAGS = 1'b0;   // 32 way

parameter FOURWAY = 1'b1;

input rst;

input clk;

input nxt;

input wr;

output wr_ack;

output rd_ack;

input xsel;

input [37:0] adr;

input [2:0] cnt;

input exv_i;

input [63:0] i;

input err_i;

output [287:0] o;

output hit;

input invall;

input invline;

wire lv;            // line valid

wire [8:0] lineno;

wire taghit;

reg wr1,wr2;

reg [2:0] sel1,sel2;

reg [63:0] i1,i2;

reg [37:0] last_adr;

// Must update the cache memory on the cycle after a write to the tag memmory.

// Otherwise lineno won't be valid. camTag memory takes two clock cycles to update.

always @(posedge clk)

        wr1 <= wr;

always @(posedge clk)

        wr2 <= wr1;

always @(posedge clk)

        sel1 <= {xsel,adr[4:3]};

always @(posedge clk)

        sel2 <= sel1;

always @(posedge clk)

        last_adr <= adr;

reg [3:0] rdackx;

always @(posedge clk)

if (rst)

        rdackx <= 4'b0;

else begin

        if (last_adr != adr || wr || wr1 || wr2)

                rdackx <= 4'b0;

        else

                rdackx <= {rdackx,~(wr|wr1|wr2)};

end

assign rd_ack = rdackx[3] & ~(last_adr!=adr || wr || wr1 || wr2);

// An exception is forced to be stored in the event of an error loading the

// the instruction line.

always @(posedge clk)

     i1 <= err_i ? {2{15'd0,1'b0,`FLT_IBE,2'b00,`BRK}} : exv_i ? {2{15'd0,1'b0,`FLT_EXF,2'b00,`BRK}} : i;

always @(posedge clk)

     i2 <= i1;

wire pe_wr;

edge_det u3 (.rst(rst), .clk(clk), .ce(1'b1), .i(wr && cnt==3'd0), .pe(pe_wr), .ne(), .ee() );