[fpgaboy.git] / System.v

`timescale 1ns / 1ps
module ROM(
        input [15:0] address,
        inout [7:0] data,
        input clk,
        input wr, rd);

        reg rdlatch = 0;
        reg [7:0] odata;

        // synthesis attribute ram_style of rom is block
        reg [7:0] rom [1023:0];
        initial $readmemh("rom.hex", rom);

        wire decode = address[15:13] == 0;
        always @(posedge clk) begin
                rdlatch <= rd && decode;
                odata <= rom[address[10:0]];
        end
        assign data = rdlatch ? odata : 8'bzzzzzzzz;
endmodule

module BootstrapROM(
        input [15:0] address,
        inout [7:0] data,
        input clk,
        input wr, rd);

        reg rdlatch = 0;
        reg [7:0] addrlatch = 0;
        reg romno = 0, romnotmp = 0;
        reg [7:0] brom0 [255:0];
        reg [7:0] brom1 [255:0];
        
        initial $readmemh("fpgaboot.hex", brom0);
        initial $readmemh("gbboot.hex", brom1);

        wire decode = address[15:8] == 0;
        wire [7:0] odata = (romno == 0) ? brom0[addrlatch] : brom1[addrlatch];
        always @(posedge clk) begin
                rdlatch <= rd && decode;
                addrlatch <= address[7:0];
                if (wr && decode) romnotmp <= data[0];
                if (rd && address == 16'h0000) romno <= romnotmp;       /* Latch when the program restarts. */
        end
        assign data = rdlatch ? odata : 8'bzzzzzzzz;
endmodule

module MiniRAM(
        input [15:0] address,
        inout [7:0] data,
        input clk,
        input wr, rd);
        
        reg [7:0] ram [127:0];
        
        wire decode = (address >= 16'hFF80) && (address <= 16'hFFFE);
        reg rdlatch = 0;
        reg [7:0] odata;
        assign data = rdlatch ? odata : 8'bzzzzzzzz;
        
        always @(posedge clk)
        begin
                rdlatch <= rd && decode;
                if (decode)             // This has to go this way. The only way XST knows how to do
                begin                   // block ram is chip select, write enable, and always
                        if (wr)         // reading. "else if rd" does not cut it ...
                                ram[address[6:0]] <= data;
                        odata <= ram[address[6:0]];
                end
        end
endmodule

module CellularRAM(
        input clk,
        input [15:0] address,
        inout [7:0] data,
        input wr, rd,
        output wire cr_nADV, cr_nCE, cr_nOE, cr_nWE, cr_CRE, cr_nLB, cr_nUB, cr_CLK,
        output wire [22:0] cr_A,
        inout [15:0] cr_DQ);
        
        parameter ADDR_PROGADDRH = 16'hFF60;
        parameter ADDR_PROGADDRM = 16'hFF61;
        parameter ADDR_PROGADDRL = 16'hFF62;
        parameter ADDR_PROGDATA = 16'hFF63;
        
        reg rdlatch = 0, wrlatch = 0;
        reg [15:0] addrlatch = 0;
        reg [7:0] datalatch = 0;
        
        reg [7:0] progaddrh, progaddrm, progaddrl;
        
        assign cr_nADV = 0;     /* Addresses are always valid! :D */
        assign cr_nCE = 0;      /* The chip is enabled */
        assign cr_nLB = 0;      /* Lower byte is enabled */
        assign cr_nUB = 0;      /* Upper byte is enabled */
        assign cr_CRE = 0;      /* Data writes, not config */
        assign cr_CLK = 0;      /* Clock? I think not! */
        
        wire decode = (addrlatch[15:14] == 2'b00) /* extrom */ || (addrlatch[15:13] == 3'b101) /* extram */ || (addrlatch == ADDR_PROGDATA);
        
        assign cr_nOE = decode ? ~rdlatch : 1;
        assign cr_nWE = decode ? ~wrlatch : 1;
        
        assign cr_DQ = (~cr_nOE) ? 16'bzzzzzzzzzzzzzzzz : {8'b0, datalatch};
        assign cr_A = (addrlatch[15:14] == 2'b00) ? /* extrom */ {9'b0,addrlatch[13:0]} :
                        (addrlatch[15:13] == 3'b101) ? {1'b1, 9'b0, addrlatch[12:0]} :
                        (addrlatch == ADDR_PROGDATA) ? {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]} :
                        23'b0;
        
        reg [7:0] regbuf;
        
        always @(posedge clk) begin
                case (address)
                ADDR_PROGADDRH: if (wr) progaddrh <= data;
                ADDR_PROGADDRM: if (wr) progaddrm <= data;
                ADDR_PROGADDRL: if (wr) progaddrl <= data;
                endcase
                rdlatch <= rd;
                wrlatch <= wr;
                addrlatch <= address;
                datalatch <= data;
        end
        
        assign data = (rdlatch && decode) ?
                                (addrlatch == ADDR_PROGADDRH) ? progaddrh :
                                (addrlatch == ADDR_PROGADDRM) ? progaddrm :
                                (addrlatch == ADDR_PROGADDRL) ? progaddrl :
                                cr_DQ
                        : 8'bzzzzzzzz;
endmodule

module InternalRAM(
        input [15:0] address,
        inout [7:0] data,
        input clk,
        input wr, rd);
        
        // synthesis attribute ram_style of ram is block
        reg [7:0] ram [8191:0];
        
        wire decode = (address >= 16'hC000) && (address <= 16'hFDFF);   /* This includes echo RAM. */
        reg [7:0] odata;
        reg rdlatch = 0;
        assign data = rdlatch ? odata : 8'bzzzzzzzz;
        
        always @(posedge clk)
        begin
                rdlatch <= rd && decode;
                if (decode)             // This has to go this way. The only way XST knows how to do
                begin                   // block ram is chip select, write enable, and always
                        if (wr)         // reading. "else if rd" does not cut it ...
                                ram[address[12:0]] <= data;
                        odata <= ram[address[12:0]];
                end
        end
endmodule

module Switches(
        input [15:0] address,
        inout [7:0] data,
        input clk,
        input wr, rd,
        input [7:0] switches,
        output reg [7:0] ledout = 0);
        
        wire decode = address == 16'hFF51;
        reg [7:0] odata;
        reg rdlatch = 0;
        assign data = rdlatch ? odata : 8'bzzzzzzzz;
        
        always @(posedge clk)
        begin
                rdlatch <= rd && decode;
                if (decode && rd)
                        odata <= switches;
                else if (decode && wr)
                        ledout <= data;
        end
endmodule

`ifdef isim
module Dumpable(input [2:0] r, g, input [1:0] b, input hs, vs, vgaclk);
endmodule
`endif

module CoreTop(
`ifdef isim
        output reg vgaclk = 0,
        output reg clk = 0,
`else
        input xtal,
        input [7:0] switches,
        input [3:0] buttons,
        output wire [7:0] leds,
        output serio,
        output wire [3:0] digits,
        output wire [7:0] seven,
        output wire cr_nADV, cr_nCE, cr_nOE, cr_nWE, cr_CRE, cr_nLB, cr_nUB, cr_CLK,
        output wire [22:0] cr_A,
        inout [15:0] cr_DQ,
`endif
        output wire hs, vs,
        output wire [2:0] r, g,
        output wire [1:0] b,
        output wire soundl, soundr);

`ifdef isim
        always #62 clk <= ~clk;
        always #100 vgaclk <= ~vgaclk;
        
        Dumpable dump(r,g,b,hs,vs,vgaclk);
        
        wire [7:0] leds;
        wire serio;
        wire [3:0] digits;
        wire [7:0] seven;
        wire [7:0] switches = 8'b0;
        wire [3:0] buttons = 4'b0;
`else   
        wire xtalb, clk, vgaclk;
        IBUFG iclkbuf(.O(xtalb), .I(xtal));
        CPUDCM dcm (.CLKIN_IN(xtalb), .CLKFX_OUT(clk));
        pixDCM pixdcm (.CLKIN_IN(xtalb), .CLKFX_OUT(vgaclk));
`endif

        wire [15:0] addr [1:0];
        wire [7:0] data [1:0];
        wire wr [1:0], rd [1:0];
        
        wire irq, tmrirq, lcdcirq, vblankirq;
        wire [7:0] jaddr;
        wire [1:0] state;
        
        GBZ80Core core(
                .clk(clk),
                .bus0address(addr[0]),
                .bus0data(data[0]),
                .bus0wr(wr[0]),
                .bus0rd(rd[0]),
                .bus1address(addr[1]),
                .bus1data(data[1]),
                .bus1wr(wr[1]),
                .bus1rd(rd[1]),
                .irq(irq),
                .jaddr(jaddr),
                .state(state));
        
        BootstrapROM brom(
                .address(addr[1]),
                .data(data[1]),
                .clk(clk),
                .wr(wr[1]),
                .rd(rd[1]));
        
`ifdef isim
        ROM rom(
                .address(addr[0]),
                .data(data[0]),
                .clk(clk),
                .wr(wr[0]),
                .rd(rd[0]));
`else
        CellularRAM cellram(
                .address(addr[0]),
                .data(data[0]),
                .clk(clk),
                .wr(wr[0]),
                .rd(rd[0]),
                .cr_nADV(cr_nADV),
                .cr_nCE(cr_nCE),
                .cr_nOE(cr_nOE),
                .cr_nWE(cr_nWE),
                .cr_CRE(cr_CRE),
                .cr_nLB(cr_nLB),
                .cr_nUB(cr_nUB),
                .cr_CLK(cr_CLK),
                .cr_A(cr_A),
                .cr_DQ(cr_DQ));
`endif
        
        wire lcdhs, lcdvs, lcdclk;
        wire [2:0] lcdr, lcdg;
        wire [1:0] lcdb;
        
        LCDC lcdc(
                .clk(clk),
                .addr(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0]),
                .lcdcirq(lcdcirq),
                .vblankirq(vblankirq),
                .lcdclk(lcdclk),
                .lcdhs(lcdhs),
                .lcdvs(lcdvs),
                .lcdr(lcdr),
                .lcdg(lcdg),
                .lcdb(lcdb));
        
        Framebuffer fb(
                .lcdclk(lcdclk),
                .lcdhs(lcdhs),
                .lcdvs(lcdvs),
                .lcdr(lcdr),
                .lcdg(lcdg),
                .lcdb(lcdb),
                .vgaclk(vgaclk),
                .vgahs(hs),
                .vgavs(vs),
                .vgar(r),
                .vgag(g),
                .vgab(b));
        
        AddrMon amon(
                .clk(clk), 
                .addr(addr[0]),
                .digit(digits), 
                .out(seven),
                .freeze(buttons[0]),
                .periods(
                        (state == 2'b00) ? 4'b0010 :
                        (state == 2'b01) ? 4'b0001 :
                        (state == 2'b10) ? 4'b1000 :
                                           4'b0100) );
         
        Switches sw(
                .clk(clk),
                .address(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0]),
                .ledout(leds),
                .switches(switches)
                );

        UART nouart (   /* no u */
                .clk(clk),
                .addr(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0]),
                .serial(serio)
                );

        InternalRAM ram(
                .clk(clk),
                .address(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0])
                );
        
        MiniRAM mram(
                .clk(clk),
                .address(addr[1]),
                .data(data[1]),
                .wr(wr[1]),
                .rd(rd[1])
                );

        Timer tmr(
                .clk(clk),
                .addr(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0]),
                .irq(tmrirq)
                );
        
        Interrupt intr(
                .clk(clk),
                .addr(addr[0]),
                .data(data[0]),
                .wr(wr[0]),
                .rd(rd[0]),
                .vblank(vblankirq),
                .lcdc(lcdcirq),
                .tovf(tmrirq),
                .serial(1'b0),
                .buttons(1'b0),
                .master(irq),
                .jaddr(jaddr));
        
        Soundcore sound(
                .core_clk(clk),
                .addr(addr[0]),
                .data(data[0]),
                .rd(rd[0]),
                .wr(wr[0]),
                .snd_data_l(soundl),
                .snd_data_r(soundr));
endmodule