c64.sv

//============================================================================
//  C64 Top level for MiSTer
//  Copyright (C) 2017-2021 Sorgelig
//
//  Used DE2-35 Top level by Dar (darfpga@aol.fr)
//
//  FPGA64 is Copyrighted 2005-2008 by Peter Wendrich (pwsoft@syntiac.com)
//  http://www.syntiac.com/fpga64.html
//
//
//  This program is free software; you can redistribute it and/or modify it
//  under the terms of the GNU General Public License as published by the Free
//  Software Foundation; either version 2 of the License, or (at your option)
//  any later version.
//
//  This program 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, write to the Free Software Foundation, Inc.,
//  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//============================================================================ 

module emu
(
	//Master input clock
	input         CLK_50M,

	//Async reset from top-level module.
	//Can be used as initial reset.
	input         RESET,

	//Must be passed to hps_io module
	inout  [48:0] HPS_BUS,

	//Base video clock. Usually equals to CLK_SYS.
	output        CLK_VIDEO,

	//Multiple resolutions are supported using different CE_PIXEL rates.
	//Must be based on CLK_VIDEO
	output        CE_PIXEL,

	//Video aspect ratio for HDMI. Most retro systems have ratio 4:3.
	//if VIDEO_ARX[12] or VIDEO_ARY[12] is set then [11:0] contains scaled size instead of aspect ratio.
	output [12:0] VIDEO_ARX,
	output [12:0] VIDEO_ARY,

	output  [7:0] VGA_R,
	output  [7:0] VGA_G,
	output  [7:0] VGA_B,
	output        VGA_HS,
	output        VGA_VS,
	output        VGA_DE,    // = ~(VBlank | HBlank)
	output        VGA_F1,
	output [1:0]  VGA_SL,
	output        VGA_SCALER, // Force VGA scaler

	input  [11:0] HDMI_WIDTH,
	input  [11:0] HDMI_HEIGHT,
	output        HDMI_FREEZE,

`ifdef MISTER_FB
	// Use framebuffer in DDRAM (USE_FB=1 in qsf)
	// FB_FORMAT:
	//    [2:0] : 011=8bpp(palette) 100=16bpp 101=24bpp 110=32bpp
	//    [3]   : 0=16bits 565 1=16bits 1555
	//    [4]   : 0=RGB  1=BGR (for 16/24/32 modes)
	//
	// FB_STRIDE either 0 (rounded to 256 bytes) or multiple of pixel size (in bytes)
	output        FB_EN,
	output  [4:0] FB_FORMAT,
	output [11:0] FB_WIDTH,
	output [11:0] FB_HEIGHT,
	output [31:0] FB_BASE,
	output [13:0] FB_STRIDE,
	input         FB_VBL,
	input         FB_LL,
	output        FB_FORCE_BLANK,

`ifdef MISTER_FB_PALETTE
	// Palette control for 8bit modes.
	// Ignored for other video modes.
	output        FB_PAL_CLK,
	output  [7:0] FB_PAL_ADDR,
	output [23:0] FB_PAL_DOUT,
	input  [23:0] FB_PAL_DIN,
	output        FB_PAL_WR,
`endif
`endif

	output        LED_USER,  // 1 - ON, 0 - OFF.

	// b[1]: 0 - LED status is system status OR'd with b[0]
	//       1 - LED status is controled solely by b[0]
	// hint: supply 2'b00 to let the system control the LED.
	output  [1:0] LED_POWER,
	output  [1:0] LED_DISK,

	// I/O board button press simulation (active high)
	// b[1]: user button
	// b[0]: osd button
	output  [1:0] BUTTONS,

	input         CLK_AUDIO, // 24.576 MHz
	output [15:0] AUDIO_L,
	output [15:0] AUDIO_R,
	output        AUDIO_S,   // 1 - signed audio samples, 0 - unsigned
	output  [1:0] AUDIO_MIX, // 0 - no mix, 1 - 25%, 2 - 50%, 3 - 100% (mono)

	//ADC
	inout   [3:0] ADC_BUS,

	//SD-SPI
	output        SD_SCK,
	output        SD_MOSI,
	input         SD_MISO,
	output        SD_CS,
	input         SD_CD,

	//High latency DDR3 RAM interface
	//Use for non-critical time purposes
	output        DDRAM_CLK,
	input         DDRAM_BUSY,
	output  [7:0] DDRAM_BURSTCNT,
	output [28:0] DDRAM_ADDR,
	input  [63:0] DDRAM_DOUT,
	input         DDRAM_DOUT_READY,
	output        DDRAM_RD,
	output [63:0] DDRAM_DIN,
	output  [7:0] DDRAM_BE,
	output        DDRAM_WE,

	//SDRAM interface with lower latency
	output        SDRAM_CLK,
	output        SDRAM_CKE,
	output [12:0] SDRAM_A,
	output  [1:0] SDRAM_BA,
	inout  [15:0] SDRAM_DQ,
	output        SDRAM_DQML,
	output        SDRAM_DQMH,
	output        SDRAM_nCS,
	output        SDRAM_nCAS,
	output        SDRAM_nRAS,
	output        SDRAM_nWE,

`ifdef MISTER_DUAL_SDRAM
	//Secondary SDRAM
	//Set all output SDRAM_* signals to Z ASAP if SDRAM2_EN is 0
	input         SDRAM2_EN,
	output        SDRAM2_CLK,
	output [12:0] SDRAM2_A,
	output  [1:0] SDRAM2_BA,
	inout  [15:0] SDRAM2_DQ,
	output        SDRAM2_nCS,
	output        SDRAM2_nCAS,
	output        SDRAM2_nRAS,
	output        SDRAM2_nWE,
`endif

	input         UART_CTS,
	output        UART_RTS,
	input         UART_RXD,
	output        UART_TXD,
	output        UART_DTR,
	input         UART_DSR,

	// Open-drain User port.
	// 0 - D+/RX
	// 1 - D-/TX
	// 2..6 - USR2..USR6
	// Set USER_OUT to 1 to read from USER_IN.
	input   [6:0] USER_IN,
	output  [6:0] USER_OUT,

	input         OSD_STATUS
);

assign {DDRAM_CLK, DDRAM_BURSTCNT, DDRAM_ADDR, DDRAM_DIN, DDRAM_BE, DDRAM_RD, DDRAM_WE} = 0;
assign {SD_SCK, SD_MOSI, SD_CS} = 'Z;

assign LED_DISK   = 0;
assign LED_POWER  = 0;
assign LED_USER   = |drive_led | ioctl_download | tape_led;
assign BUTTONS    = 0;
assign VGA_SCALER = 0;

// Status Bit Map:
//              Upper                          Lower
// 0         1         2         3          4         5         6
// 01234567890123456789012345678901 23456789012345678901234567890123
// 0123456789ABCDEFGHIJKLMNOPQRSTUV 0123456789ABCDEFGHIJKLMNOPQRSTUV
// XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXX

`include "build_id.v"
localparam CONF_STR = {
	"C64;UART9600:2400;",
	"H7S0,D64G64T64D81,Mount #8;",
	"H0S1,D64G64T64D81,Mount #9;",
	"-;",
	"F1,PRGCRTREUTAP;",
	"h3-;",
	"h3R7,Tape Play/Pause;",
	"h3RN,Tape Unload;",
	"h3OB,Tape Sound,Off,On;",
	"-;",

	"P1,Audio & Video;", 
	"P1O2,Video Standard,PAL,NTSC;",
	"P1O45,Aspect Ratio,Original,Full Screen,[ARC1],[ARC2];",
	"P1O8A,Scandoubler Fx,None,HQ2x-320,HQ2x-160,CRT 25%,CRT 50%,CRT 75%;",
	"d1P1o0,Vertical Crop,No,Yes;",
	"P1OUV,Scale,Normal,V-Integer,Narrower HV-Integer,Wider HV-Integer;",
	"P1-;",
	"P1OD,Left SID,6581,8580;",
	"D4P1o23,Left Filter,Default,Custom 1,Custom 2,Custom 3;",
	"P1OG,Right SID,6581,8580;",
	"D5P1o56,Right Filter,Default,Custom 1,Custom 2,Custom 3;",
	"P1OKM,Right SID Port,Same,DE00,D420,D500,DF00;",
	"P1FC7,FLT,Load Custom Filters;",
	"P1-;",
	"P1OC,Sound Expander,Disabled,OPL2;",
	"P1o89,DigiMax,Disabled,DE00,DF00;",
	"P1OIJ,Stereo Mix,None,25%,50%,100%;",

	"P2,Hardware;", 
	"P2oPQ,Enable Drive #8,If Mounted,Always,Never;",
	"P2oNO,Enable Drive #9,If Mounted,Always,Never;",
	"P2oC,Parallel port,Enabled,Disabled;",
	"P2R6,Reset Disk Drives;",
	"P2-;",
	"P2oK,GeoRAM,Disabled,4MB;",
	"P2oLM,REU,Disabled,512KB,2MB (512KB wrap),16MB;",
	"P2-;",
	"P2OP,External IEC,Disabled,Enabled;",
	"P2oB,Expansion,Joysticks,RS232;",
	"P2oJ,RS232 mode,UP9600,VIC-1011;",
	"P2o1,RS232 connection,Internal,External;",
	"P2o4,Real-Time Clock,Auto,Disabled;",
	"P2oD,CIA Model,6526,8521;",
	"P2-;",
	"P2OQR,Pot 1/2,Joy 1 Fire 2/3,Mouse,Paddles 1/2;",
	"P2OST,Pot 3/4,Joy 2 Fire 2/3,Mouse,Paddles 3/4;",
	"P2-;",
	"P2O1,Release Keys on Reset,Yes,No;",
	"P2OO,Clear RAM on Reset,Yes,No;",
	"P2oI,Reset & Run PRG,Yes,No;",
	"P2oA,Pause When OSD is Open,No,Yes;",
	"P2o7,Tape Autoplay,Yes,No;",
	"P2-;",
	"P2FC8,ROM,System ROM C64+C1541 ;",
	"P2FC9,ROM,System ROM C1581     ;",
	"P2FC5,CRT,Boot Cartridge       ;",
	"P2-;",
	"P2OEF,System ROM,Loadable C64,Standard C64,C64GS,Japanese;",

	"-;",
	"O3,Swap Joysticks,No,Yes;",
	"-;",
	"oEF,Turbo mode,Off,C128,Smart;",
	"d6oGH,Turbo speed,2x,3x,4x;",
	"-;",
	"R0,Reset;",
	"RH,Reset & Detach Cartridge;",
	"J,Fire 1,Fire 2,Fire 3,Paddle Btn,Mod1,Mod2;",
	"jn,A,B,Y,X|P,R,L;",
	"jp,A,B,Y,X|P,R,L;",
	"V,v",`BUILD_DATE
};


wire pll_locked;
wire clk_sys;
wire clk64;
wire clk48;

pll pll
(
	.refclk(CLK_50M),
	.outclk_0(clk48),
	.outclk_1(clk64),
	.outclk_2(clk_sys),
	.reconfig_to_pll(reconfig_to_pll),
	.reconfig_from_pll(reconfig_from_pll),
	.locked(pll_locked)
);

wire [63:0] reconfig_to_pll;
wire [63:0] reconfig_from_pll;
wire        cfg_waitrequest;
reg         cfg_write;
reg   [5:0] cfg_address;
reg  [31:0] cfg_data;

pll_cfg pll_cfg
(
	.mgmt_clk(CLK_50M),
	.mgmt_reset(0),
	.mgmt_waitrequest(cfg_waitrequest),
	.mgmt_read(0),
	.mgmt_readdata(),
	.mgmt_write(cfg_write),
	.mgmt_address(cfg_address),
	.mgmt_writedata(cfg_data),
	.reconfig_to_pll(reconfig_to_pll),
	.reconfig_from_pll(reconfig_from_pll)
);

always @(posedge CLK_50M) begin
	reg ntscd = 0, ntscd2 = 0;
	reg [2:0] state = 0;
	reg ntsc_r;

	ntscd <= ntsc;
	ntscd2 <= ntscd;

	cfg_write <= 0;
	if(ntscd2 == ntscd && ntscd2 != ntsc_r) begin
		state <= 1;
		ntsc_r <= ntscd2;
	end

	if(!cfg_waitrequest) begin
		if(state) state<=state+1'd1;
		case(state)
			1: begin
					cfg_address <= 0;
					cfg_data <= 0;
					cfg_write <= 1;
				end
				/*
			3: begin
					cfg_address <= 4;
					cfg_data <= ntsc_r ? 'h20504 : 'h404;
					cfg_write <= 1;
				end
				*/
			5: begin
					cfg_address <= 7;
					cfg_data <= ntsc_r ? 3357876127 : 1503512573;
					cfg_write <= 1;
				end
			7: begin
					cfg_address <= 2;
					cfg_data <= 0;
					cfg_write <= 1;
				end
		endcase
	end
end

reg reset_n;
reg reset_wait = 0;
always @(posedge clk_sys) begin
	integer reset_counter;
	reg old_download;
	reg do_erase = 1;

	reset_n <= !reset_counter;
	old_download <= ioctl_download;

	if (RESET | status[0] | status[17] | buttons[1] | !pll_locked) begin
		if(RESET) do_erase <= 1;
		reset_counter <= 100000;
	end
	else if(~old_download & ioctl_download & load_prg & ~status[50]) begin
		do_erase <= 1;
		reset_wait <= 1;
		reset_counter <= 255;
	end
	else if (ioctl_download & (load_crt | load_rom)) begin
		do_erase <= 1;
		reset_counter <= 255;
	end
	else if ((ioctl_download || inj_meminit) & ~reset_wait);
	else if (erasing) force_erase <= 0;
	else if (!reset_counter) begin
		do_erase <= 0;
		if(reset_wait && c64_addr == 'hFFCF) reset_wait <= 0;
	end
	else begin
		reset_counter <= reset_counter - 1;
		if (reset_counter == 100 && (~status[24] | do_erase)) force_erase <= 1;
	end
end

wire [15:0] joyA,joyB,joyC,joyD;
wire [15:0] joy = joyA | joyB | joyC | joyD;

wire [63:0] status;
wire        forced_scandoubler;

wire        ioctl_wr;
wire [24:0] ioctl_addr;
wire  [7:0] ioctl_data;
wire  [7:0] ioctl_index;
wire        ioctl_download;

wire [31:0] sd_lba[2];
wire  [5:0] sd_blk_cnt[2];
wire  [1:0] sd_rd;
wire  [1:0] sd_wr;
wire  [1:0] sd_ack;
wire [13:0] sd_buff_addr;
wire  [7:0] sd_buff_dout;
wire  [7:0] sd_buff_din[2];
wire        sd_buff_wr;
wire  [1:0] img_mounted;
wire [31:0] img_size;
wire        img_readonly;

wire [24:0] ps2_mouse;
wire [10:0] ps2_key;
wire  [1:0] buttons;
wire [21:0] gamma_bus;

wire  [7:0] pd1,pd2,pd3,pd4;

wire [64:0] RTC;

hps_io #(.CONF_STR(CONF_STR), .VDNUM(2), .BLKSZ(1)) hps_io
(
	.clk_sys(clk_sys),
	.HPS_BUS(HPS_BUS),

	.joystick_0(joyA),
	.joystick_1(joyB),
	.joystick_2(joyC),
	.joystick_3(joyD),

	.paddle_0(pd1),
	.paddle_1(pd2),
	.paddle_2(pd3),
	.paddle_3(pd4),

	.status(status),
	.status_menumask({status[58], |status[47:46], status[16], status[13], tap_loaded, 1'b0, |vcrop, status[56]}),
	.buttons(buttons),
	.forced_scandoubler(forced_scandoubler),
	.gamma_bus(gamma_bus),

	.sd_lba(sd_lba),
	.sd_blk_cnt(sd_blk_cnt),
	.sd_rd(sd_rd),
	.sd_wr(sd_wr),
	.sd_ack(sd_ack),

	.sd_buff_addr(sd_buff_addr),
	.sd_buff_dout(sd_buff_dout),
	.sd_buff_din(sd_buff_din),
	.sd_buff_wr(sd_buff_wr),
	.img_mounted(img_mounted),
	.img_size(img_size),
	.img_readonly(img_readonly),

	.ps2_key(ps2_key),
	.ps2_mouse(ps2_mouse),

	.RTC(RTC),

	.ioctl_download(ioctl_download),
	.ioctl_index(ioctl_index),
	.ioctl_wr(ioctl_wr),
	.ioctl_addr(ioctl_addr),
	.ioctl_dout(ioctl_data),
	.ioctl_wait(ioctl_req_wr|reset_wait)
);

wire load_prg   = ioctl_index == 'h01;
wire load_crt   = ioctl_index == 'h41 || ioctl_index == 5;
wire load_reu   = ioctl_index == 'h81;
wire load_tap   = ioctl_index == 'hC1;
wire load_flt   = ioctl_index == 7;
wire load_rom   = ioctl_index == 8;
wire load_c1581 = ioctl_index == 9;

wire game;
wire exrom;
wire io_rom;
wire cart_ce;
wire cart_we;
wire nmi;
wire cart_oe;
wire IOF_rd;
wire  [7:0] cart_data;
wire [24:0] cart_addr;

cartridge cartridge
(
	.clk32(clk_sys),
	.reset_n(reset_n),

	.cart_loading(ioctl_download && load_crt),
	.cart_id(cart_attached ? cart_id : status[52] ? 8'd99 : 8'd255),
	.cart_exrom(cart_exrom),
	.cart_game(cart_game),
	.cart_bank_laddr(cart_bank_laddr),
	.cart_bank_size(cart_bank_size),
	.cart_bank_num(cart_bank_num),
	.cart_bank_type(cart_bank_type),
	.cart_bank_raddr(ioctl_load_addr),
	.cart_bank_wr(cart_hdr_wr),

	.exrom(exrom),
	.game(game),

	.romL(romL),
	.romH(romH),
	.UMAXromH(UMAXromH),
	.IOE(IOE),
	.IOF(IOF),
	.mem_write(ram_we),
	.mem_ce(ram_ce),
	.mem_ce_out(cart_ce),
	.mem_write_out(cart_we),
	.IO_rom(io_rom),
	.IO_rd(cart_oe),
	.IO_data(cart_data),
	.addr_in(c64_addr),
	.data_in(c64_data_out),
	.addr_out(cart_addr),

	.freeze_key(freeze_key),
	.mod_key(mod_key),
	.nmi(nmi),
	.nmi_ack(nmi_ack)
);

wire        dma_req;
wire        dma_cycle;
wire [15:0] dma_addr;
wire  [7:0] dma_dout;
wire  [7:0] dma_din;
wire        dma_we;
wire        ext_cycle;

wire [24:0] reu_ram_addr;
wire  [7:0] reu_ram_dout;
wire        reu_ram_we;

wire  [7:0] reu_dout;
wire        reu_irq;

wire        reu_oe  = IOF && reu_cfg;
wire  [1:0] reu_cfg = status[54:53];

reu reu
(
	.clk(clk_sys),
	.reset(~reset_n),
	.cfg(reu_cfg),

	.dma_req(dma_req),

	.dma_cycle(dma_cycle),
	.dma_addr(dma_addr),
	.dma_dout(dma_dout),
	.dma_din(dma_din),
	.dma_we(dma_we),

	.ram_cycle(ext_cycle),
	.ram_addr(reu_ram_addr),
	.ram_dout(reu_ram_dout),
	.ram_din(sdram_data),
	.ram_we(reu_ram_we),
	
	.cpu_addr(c64_addr),
	.cpu_dout(c64_data_out),
	.cpu_din(reu_dout),
	.cpu_we(ram_we),
	.cpu_cs(IOF),
	
	.irq(reu_irq)
);

reg ext_cycle_d;
always @(posedge clk_sys) ext_cycle_d <= ext_cycle;
wire reu_ram_ce = ~ext_cycle_d & ext_cycle & dma_req;

// rearrange joystick contacts for c64
wire [6:0] joyA_int = joy[8] ? 7'd0 : {joyA[6:4], joyA[0], joyA[1], joyA[2], joyA[3]};
wire [6:0] joyB_int = joy[8] ? 7'd0 : {joyB[6:4], joyB[0], joyB[1], joyB[2], joyB[3]};
wire [6:0] joyC_c64 = joy[8] ? 7'd0 : {joyC[6:4], joyC[0], joyC[1], joyC[2], joyC[3]};
wire [6:0] joyD_c64 = joy[8] ? 7'd0 : {joyD[6:4], joyD[0], joyD[1], joyD[2], joyD[3]};

// swap joysticks if requested
wire [6:0] joyA_c64 = status[3] ? joyB_int : joyA_int;
wire [6:0] joyB_c64 = status[3] ? joyA_int : joyB_int;

wire [7:0] paddle_1 = status[3] ? pd3 : pd1;
wire [7:0] paddle_2 = status[3] ? pd4 : pd2;
wire [7:0] paddle_3 = status[3] ? pd1 : pd3;
wire [7:0] paddle_4 = status[3] ? pd2 : pd4;

wire       paddle_1_btn = ~joy[8] & (status[3] ? joyC[7] : joyA[7]);
wire       paddle_2_btn = ~joy[8] & (status[3] ? joyD[7] : joyB[7]);
wire       paddle_3_btn = ~joy[8] & (status[3] ? joyA[7] : joyC[7]);
wire       paddle_4_btn = ~joy[8] & (status[3] ? joyB[7] : joyD[7]);

wire [1:0] pd12_mode = status[27:26];
wire [1:0] pd34_mode = status[29:28];

reg [24:0] ioctl_load_addr;
reg        ioctl_req_wr;

reg [15:0] cart_id;
reg [15:0] cart_bank_laddr;
reg [15:0] cart_bank_size;
reg [15:0] cart_bank_num;
reg  [7:0] cart_bank_type;
reg  [7:0] cart_exrom;
reg  [7:0] cart_game;
reg        cart_attached = 0;
reg  [3:0] cart_hdr_cnt;
reg        cart_hdr_wr;
reg [31:0] cart_blk_len;

reg        force_erase;
reg        erasing;

reg        inj_meminit = 0;

wire       io_cycle;
reg        io_cycle_ce;
reg        io_cycle_we;
reg [24:0] io_cycle_addr;
reg  [7:0] io_cycle_data;

localparam TAP_ADDR = 25'h0200000;
localparam REU_ADDR = 25'h1000000;

always @(posedge clk_sys) begin
	reg  [4:0] erase_to;
	reg        old_download;
	reg        erase_cram;
	reg        io_cycleD;
	reg        old_st0 = 0;
	reg        old_meminit;
	reg [15:0] inj_end;
	reg  [7:0] inj_meminit_data;

	old_download <= ioctl_download;
	io_cycleD <= io_cycle;
	cart_hdr_wr <= 0;
	
	if (~io_cycle & io_cycleD) begin
		io_cycle_ce <= 1;
		io_cycle_we <= 0;
		io_cycle_addr <= tap_play_addr + TAP_ADDR;
		if (ioctl_req_wr) begin
			ioctl_req_wr <= 0;
			io_cycle_we <= 1;
			io_cycle_addr <= ioctl_load_addr;
			ioctl_load_addr <= ioctl_load_addr + 1'b1;
			if (erasing) io_cycle_data <= {8{ioctl_load_addr[6]}};
			else if (inj_meminit) io_cycle_data <= inj_meminit_data;
			else io_cycle_data <= ioctl_data;
		end
	end

	if (io_cycle & io_cycleD) {io_cycle_ce, io_cycle_we} <= 0;

	if (ioctl_wr) begin
		if (load_prg) begin
			// PRG header
			// Load address low-byte
			if      (ioctl_addr == 0) begin ioctl_load_addr[7:0]  <= ioctl_data; inj_end[7:0]  <= ioctl_data; end
			// Load address high-byte
			else if (ioctl_addr == 1) begin ioctl_load_addr[15:8] <= ioctl_data; inj_end[15:8] <= ioctl_data; end
			else begin ioctl_req_wr <= 1; inj_end <= inj_end + 1'b1; end
		end

		if (load_crt) begin
			if (ioctl_addr == 0) begin
				ioctl_load_addr <= 24'h100000;
				cart_blk_len <= 0;
				cart_hdr_cnt <= 0;
			end 

			if (ioctl_addr == 8'h16) cart_id[15:8]   <= ioctl_data;
			if (ioctl_addr == 8'h17) cart_id[7:0]    <= ioctl_data;
			if (ioctl_addr == 8'h18) cart_exrom[7:0] <= ioctl_data;
			if (ioctl_addr == 8'h19) cart_game[7:0]  <= ioctl_data;

			if (ioctl_addr >= 8'h40) begin
				if (cart_blk_len == 0 & cart_hdr_cnt == 0) begin
					cart_hdr_cnt <= 1;
					if (ioctl_load_addr[12:0] != 0) begin
						// align to 8KB boundary
						ioctl_load_addr[12:0] <= 0;
						ioctl_load_addr[24:13] <= ioctl_load_addr[24:13] + 1'b1;
					end
				end else if (cart_hdr_cnt != 0) begin
					cart_hdr_cnt <= cart_hdr_cnt + 1'b1;
					if (cart_hdr_cnt == 4)  cart_blk_len[31:24]  <= ioctl_data;
					if (cart_hdr_cnt == 5)  cart_blk_len[23:16]  <= ioctl_data;
					if (cart_hdr_cnt == 6)  cart_blk_len[15:8]   <= ioctl_data;
					if (cart_hdr_cnt == 7)  cart_blk_len[7:0]    <= ioctl_data;
					if (cart_hdr_cnt == 8)  cart_blk_len         <= cart_blk_len - 8'h10;
					if (cart_hdr_cnt == 9)  cart_bank_type       <= ioctl_data;
					if (cart_hdr_cnt == 10) cart_bank_num[15:8]  <= ioctl_data;
					if (cart_hdr_cnt == 11) cart_bank_num[7:0]   <= ioctl_data;
					if (cart_hdr_cnt == 12) cart_bank_laddr[15:8]<= ioctl_data;
					if (cart_hdr_cnt == 13) cart_bank_laddr[7:0] <= ioctl_data;
					if (cart_hdr_cnt == 14) cart_bank_size[15:8] <= ioctl_data;
					if (cart_hdr_cnt == 15) cart_bank_size[7:0]  <= ioctl_data;
					if (cart_hdr_cnt == 15) cart_hdr_wr <= 1;
				end
				else begin
					cart_blk_len <= cart_blk_len - 1'b1;
					ioctl_req_wr <= 1;
				end
			end
		end
		
		if (load_tap) begin
			if (ioctl_addr == 0)  ioctl_load_addr <= TAP_ADDR;
			if (ioctl_addr == 12) tap_version <= ioctl_data[1:0];
			ioctl_req_wr <= 1;
		end

		if (load_reu) begin
			if (ioctl_addr == 0) ioctl_load_addr <= REU_ADDR;
			ioctl_req_wr <= 1;
		end
	end
	
	if (old_download != ioctl_download && load_crt) begin
		cart_attached <= old_download;
		erase_cram <= 1;
	end 

	// meminit for RAM injection
	if (old_download != ioctl_download && load_prg && !inj_meminit) begin
		inj_meminit <= 1;
		ioctl_load_addr <= 0;
	end

	if (inj_meminit) begin
		if (!ioctl_req_wr) begin
			// check if done
			if (ioctl_load_addr == 'h100) begin
				inj_meminit <= 0;
			end
			else begin
				ioctl_req_wr <= 1;
				
				// Initialize BASIC pointers to simulate the BASIC LOAD command
				case(ioctl_load_addr)
					// TXT (2B-2C)
					// Set these two bytes to $01, $08 just as they would be on reset (the BASIC LOAD command does not alter these)
					'h2B: inj_meminit_data <= 'h01;
					'h2C: inj_meminit_data <= 'h08;

					// SAVE_START (AC-AD)
					// Set these two bytes to zero just as they would be on reset (the BASIC LOAD command does not alter these)
					'hAC, 'hAD: inj_meminit_data <= 'h00;
					
					// VAR (2D-2E), ARY (2F-30), STR (31-32), LOAD_END (AE-AF)
					// Set these just as they would be with the BASIC LOAD command (essentially they are all set to the load end address)
					'h2D, 'h2F, 'h31, 'hAE: inj_meminit_data <= inj_end[7:0];
					'h2E, 'h30, 'h32, 'hAF: inj_meminit_data <= inj_end[15:8];
					
					default: begin
						ioctl_req_wr <= 0;
						
						// advance the address
						ioctl_load_addr <= ioctl_load_addr + 1'b1;
					end
				endcase
			end
		end
	end

	old_meminit <= inj_meminit;
	start_strk  <= old_meminit & ~inj_meminit;
	
	old_st0 <= status[17];
	if (~old_st0 & status[17]) cart_attached <= 0;
	
	if (!erasing && force_erase) begin
		erasing <= 1;
		ioctl_load_addr <= 0;
	end

	if (erasing && !ioctl_req_wr) begin
		erase_to <= erase_to + 1'b1;
		if (&erase_to) begin
			if (ioctl_load_addr < ({erase_cram, 16'hFFFF}))
				ioctl_req_wr <= 1;
			else begin
				erasing <= 0;
				erase_cram <= 0;
			end
		end
	end
end

reg        start_strk = 0;
reg        reset_keys = 0;
reg [10:0] key = 0;
always @(posedge clk_sys) begin
	reg  [3:0] act = 0;
	reg        joy_finish = 0;
	reg [17:0] joy_last = 0;
	reg [17:0] joy_key;
	int        to;

	reset_keys <= 0;

	joy_key =(joy[9:8] == 3) ?
				(joy[0] ? 18'h005 : joy[1] ? 18'h006 : joy[2] ? 18'h004 : joy[3] ? 18'h00C  :
				 joy[4] ? 18'h003 : joy[5] ? 18'h00B : joy[6] ? 18'h083 : joy[7] ? 18'h00A  : 18'h0):
				(joy[9]) ?
				(joy[0] ? 18'h016 : joy[1] ? 18'h01E : joy[2] ? 18'h026 : joy[3] ? 18'h025  :
			    joy[4] ? 18'h02E : joy[5] ? 18'h045 : joy[6] ? 18'h035 : joy[7] ? 18'h031  : 18'h0):
				(joy[0] ? 18'h174 : joy[1] ? 18'h16B : joy[2] ? 18'h172 : joy[3] ? 18'h175  : 
				 joy[4] ? 18'h05A : joy[5] ? 18'h029 : joy[6] ? 18'h076 : joy[7] ? 18'h2276 : 18'h0);
	
	if(~reset_n) {joy_finish, act} <= 0;

	if(joy[9:8]) begin
		joy_finish <= 1;
		if(!joy[7:0] && joy_last) begin
			joy_last <= 0;
			reset_keys <= 1;
		end
		else if(!joy_last[8:0] && joy_key) begin
			to <= to + 1'd1;
			if(joy_last[17:9] != joy_key[17:9]) begin
				joy_last[17:9] <= joy_key[17:9];
				key <= joy_key[17:9];
				key[9] <= 1;
				key[10] <= ~key[10];
			end
			else if(to > 640000 && joy_last[8:0] != joy_key[8:0]) begin
				joy_last[8:0] <= joy_key[8:0];
				key <= joy_key[8:0];
				key[9] <= 1;
				key[10] <= ~key[10];
			end
		end
		else begin
			to <= 0;
		end
	end
	else if(joy_finish) begin
		joy_last   <= 0;
		key        <= 0;
		key[10]    <= ps2_key[10];
		joy_finish <= 0;
		reset_keys <= 1;
	end
	else if(act) begin
		to <= to + 1;
		if(to > 1280000) begin
			to <= 0;
			act <= act + 1'd1;
			case(act)
				// PS/2 scan codes
				 1: key <= 'h2d;  // R
				 3: key <= 'h3c;  // U
				 5: key <= 'h31;  // N
				 7: key <= 'h5a;  // <RETURN>
				 9: key <= 'h00;
				10: act <= 0;
			endcase
			key[9]  <= act[0];
			key[10] <= (act >= 9) ? ps2_key[10] : ~key[10];
		end
	end
	else begin
		to <= 0;
		key <= ps2_key;
	end
	if(start_strk & ~status[50]) begin
		act <= 1;
		key <= 0;
	end
end

assign SDRAM_CKE  = 1;

wire [7:0] sdram_data;
sdram sdram
(
	.sd_addr(SDRAM_A),
	.sd_data(SDRAM_DQ),
	.sd_ba(SDRAM_BA),
	.sd_cs(SDRAM_nCS),
	.sd_we(SDRAM_nWE),
	.sd_ras(SDRAM_nRAS),
	.sd_cas(SDRAM_nCAS),
	.sd_clk(SDRAM_CLK),
	.sd_dqm({SDRAM_DQMH,SDRAM_DQML}),

	.clk(clk64),
	.init(~pll_locked),
	.refresh(refresh),
	.addr( io_cycle ? io_cycle_addr : ext_cycle ? reu_ram_addr : cart_addr    ),
	.ce  ( io_cycle ? io_cycle_ce   : ext_cycle ? reu_ram_ce   : cart_ce      ),
	.we  ( io_cycle ? io_cycle_we   : ext_cycle ? reu_ram_we   : cart_we      ),
	.din ( io_cycle ? io_cycle_data : ext_cycle ? reu_ram_dout : c64_data_out ),
	.dout( sdram_data )
);

wire  [7:0] c64_data_out;
wire [15:0] c64_addr;
wire        c64_pause;
wire        refresh;
wire        ram_ce;
wire        ram_we;
wire        nmi_ack;
wire        freeze_key;
wire        mod_key;

wire        IOE;
wire        IOF;
wire        romL;
wire        romH;
wire        UMAXromH;

wire [17:0] audio_l,audio_r;
wire  [7:0] r,g,b;

wire        ntsc = status[2];

fpga64_sid_iec fpga64
(
	.clk32(clk_sys),
	.reset_n(reset_n),
	.pause(freeze),
	.pause_out(c64_pause),
	.bios(status[15:14]),
	
	.turbo_mode({status[47] & ~disk_access, status[46]}),
	.turbo_speed(status[49:48]),

	.ps2_key(key),
	.kbd_reset((~reset_n & ~status[1]) | reset_keys),

	.ramAddr(c64_addr),
	.ramDout(c64_data_out),
	.ramDin(sdram_data),
	.ramCE(ram_ce),
	.ramWE(ram_we),

	.ntscmode(ntsc),
	.hsync(hsync),
	.vsync(vsync),
	.r(r),
	.g(g),
	.b(b),

	.game(game),
	.exrom(exrom),
	.UMAXromH(UMAXromH),
	.irq_n(1),
	.nmi_n(~nmi),
	.nmi_ack(nmi_ack),
	.freeze_key(freeze_key),
	.tape_play(tape_play),
	.mod_key(mod_key),
	.roml(romL),
	.romh(romH),
	.ioe(IOE),
	.iof(IOF),
	.io_rom(io_rom),
	.io_ext(cart_oe | reu_oe | opl_en),
	.io_data(cart_oe ? cart_data : reu_oe ? reu_dout : opl_dout),
	
	.dma_req(dma_req),
	.dma_cycle(dma_cycle),
	.dma_addr(dma_addr),
	.dma_dout(dma_dout),
	.dma_din(dma_din),
	.dma_we(dma_we),
	.irq_ext_n(~reu_irq),

	.cia_mode(status[45]),

	.joya({(pd12_mode && !joy[9:8]) ? joyA_c64[6:5] : 2'b00, joyA_c64[4:0] | {1'b0, pd12_mode[1] & paddle_2_btn, pd12_mode[1] & paddle_1_btn, 2'b00} | {pd12_mode[0] & mouse_btn[0], 3'b000, pd12_mode[0] & mouse_btn[1]}}),
	.joyb({(pd34_mode && !joy[9:8]) ? joyB_c64[6:5] : 2'b00, joyB_c64[4:0] | {1'b0, pd34_mode[1] & paddle_4_btn, pd34_mode[1] & paddle_3_btn, 2'b00} | {pd34_mode[0] & mouse_btn[0], 3'b000, pd34_mode[0] & mouse_btn[1]}}),

	.pot1(pd12_mode[1] ? paddle_1 : pd12_mode[0] ? mouse_x : {8{joyA_c64[5]}}),
	.pot2(pd12_mode[1] ? paddle_2 : pd12_mode[0] ? mouse_y : {8{joyA_c64[6]}}),
	.pot3(pd34_mode[1] ? paddle_3 : pd34_mode[0] ? mouse_x : {8{joyB_c64[5]}}),
	.pot4(pd34_mode[1] ? paddle_4 : pd34_mode[0] ? mouse_y : {8{joyB_c64[6]}}),

	.io_cycle(io_cycle),
	.ext_cycle(ext_cycle),
	.refresh(refresh),

	.sid_ld_clk(clk_sys),
	.sid_ld_addr(sid_ld_addr),
	.sid_ld_data(sid_ld_data),
	.sid_ld_wr(sid_ld_wr),
	.sid_mode(status[22:20]),
	.sid_filter(2'b11),
	.sid_ver({status[16],status[13]}),
	.sid_cfg({status[38:37],status[35:34]}),
	.audio_l(audio_l),
	.audio_r(audio_r),

	.iec_data_o(c64_iec_data),
	.iec_atn_o(c64_iec_atn),
	.iec_clk_o(c64_iec_clk),
	.iec_data_i(drive_iec_data),
	.iec_clk_i(drive_iec_clk),

	.pb_i(pb_i),
	.pb_o(pb_o),
	.pa2_i(pa2_i),
	.pa2_o(pa2_o),
	.pc2_n_o(pc2_n_o),
	.flag2_n_i(flag2_n_i),
	.sp2_i(sp2_i),
	.sp2_o(sp2_o),
	.sp1_i(sp1_i),
	.sp1_o(sp1_o),
	.cnt2_i(cnt2_i),
	.cnt2_o(cnt2_o),
	.cnt1_i(cnt1_i),
	.cnt1_o(cnt1_o),

	.c64rom_addr(ioctl_addr[13:0]),
	.c64rom_data(ioctl_data),
	.c64rom_wr(load_rom && !ioctl_addr[16:14] && ioctl_download && ioctl_wr),

	.cass_write(cass_write),
	.cass_motor(cass_motor),
	.cass_sense(~tape_adc_act & (use_tape ? cass_sense : cass_rtc)),
	.cass_read(tape_adc_act ? ~tape_adc : cass_read)
);

wire [7:0] mouse_x;
wire [7:0] mouse_y;
wire [1:0] mouse_btn;

c1351 mouse
(
	.clk_sys(clk_sys),
	.reset(~reset_n),

	.ps2_mouse(ps2_mouse),
	
	.potX(mouse_x),
	.potY(mouse_y),
	.button(mouse_btn)
);

wire       c64_iec_clk;
wire       c64_iec_data;
wire       c64_iec_atn;

wire       drive_iec_clk  = drive_iec_clk_o  & ext_iec_clk;
wire       drive_iec_data = drive_iec_data_o & ext_iec_data;

wire [7:0] drive_par_i;
wire       drive_stb_i;
wire [7:0] drive_par_o;
wire       drive_stb_o;
wire       drive_iec_clk_o;
wire       drive_iec_data_o;
wire       drive_reset = ~reset_n | status[6] | (load_c1581 & ioctl_download);

wire [1:0] drive_led;

reg [1:0] drive_mounted = 0;
always @(posedge clk_sys) begin 
	if(img_mounted[0]) drive_mounted[0] <= |img_size;
	if(img_mounted[1]) drive_mounted[1] <= |img_size;
end

iec_drive iec_drive
(
	.clk(clk_sys),
	.reset({drive_reset | ((!status[56:55]) ? ~drive_mounted[1] : status[56]),
		     drive_reset | ((!status[58:57]) ? ~drive_mounted[0] : status[58])}),

	.ce(drive_ce),

	.iec_atn_i(c64_iec_atn),
	.iec_data_i(c64_iec_data & ext_iec_data),
	.iec_clk_i(c64_iec_clk & ext_iec_clk),
	.iec_data_o(drive_iec_data_o),
	.iec_clk_o(drive_iec_clk_o),

	.pause(c64_pause),

	.img_mounted(img_mounted),
	.img_size(img_size),
	.img_readonly(img_readonly),
	.img_type(&ioctl_index[7:6] ? 2'b11 : 2'b01),

	.led(drive_led),

	.par_data_i(drive_par_i),
	.par_stb_i(drive_stb_i),
	.par_data_o(drive_par_o),
	.par_stb_o(drive_stb_o),

	.clk_sys(clk_sys),

	.sd_lba(sd_lba),
	.sd_blk_cnt(sd_blk_cnt),
	.sd_rd(sd_rd),
	.sd_wr(sd_wr),
	.sd_ack(sd_ack),
	.sd_buff_addr(sd_buff_addr),
	.sd_buff_dout(sd_buff_dout),
	.sd_buff_din(sd_buff_din),
	.sd_buff_wr(sd_buff_wr),

	.rom_addr(load_rom ? (ioctl_addr[15:0] - 16'h4000) : {1'b1,ioctl_addr[14:0]}),
	.rom_data(ioctl_data),
	.rom_wr(((load_rom && ioctl_addr[16:14]) || load_c1581) && ioctl_download && ioctl_wr),
	.rom_std(status[14])
);

reg drive_ce;
always @(posedge clk_sys) begin
	int sum = 0;
	int msum;
	
	msum <= ntsc ? 32727264 : 31527954;

	drive_ce <= 0;
	sum = sum + 16000000;
	if(sum >= msum) begin
		sum = sum - msum;
		drive_ce <= 1;
	end
end

wire disk_parport = ~status[44];

reg disk_access;
always @(posedge clk_sys) begin
	reg c64_iec_clk_old, drive_iec_clk_old, drive_stb_i_old, drive_stb_o_old;
	integer to = 0;

	c64_iec_clk_old <= c64_iec_clk;
	drive_iec_clk_old <= drive_iec_clk;
	drive_stb_i_old <= drive_stb_i;
	drive_stb_o_old <= drive_stb_o;
	
	if(((c64_iec_clk_old != c64_iec_clk) || (drive_iec_clk_old != drive_iec_clk)) || 
		(disk_parport && ((drive_stb_i_old != drive_stb_i) || (drive_stb_o_old != drive_stb_o))))
	begin
		disk_access <= 1;
		to <= 16000000; // 0.5s
	end
	else if(to) to <= to - 1;
	else disk_access <= 0;
end

wire ext_iec_en   = status[25];
wire ext_iec_clk  = USER_IN[2] | ~ext_iec_en;
wire ext_iec_data = USER_IN[4] | ~ext_iec_en;

assign USER_OUT[2] = (c64_iec_clk & drive_iec_clk_o)  | ~ext_iec_en;
assign USER_OUT[3] = (reset_n & ~status[6]) | ~ext_iec_en;
assign USER_OUT[4] = (c64_iec_data & drive_iec_data_o) | ~ext_iec_en;
assign USER_OUT[5] = c64_iec_atn | ~ext_iec_en;
assign USER_OUT[6] = '1;


wire hsync;
wire vsync;
wire hblank;
wire vblank;
wire hsync_out;
wire vsync_out;

video_sync sync
(
	.clk32(clk_sys),
	.pause(c64_pause),
	.hsync(hsync),
	.vsync(vsync),
	.ntsc(ntsc),
	.wide(wide),
	.hsync_out(hsync_out),
	.vsync_out(vsync_out),
	.hblank(hblank),
	.vblank(vblank)
);

reg hq2x160;
always @(posedge clk_sys) begin
	reg old_vsync;

	old_vsync <= vsync_out;
	if (!old_vsync && vsync_out) begin
		hq2x160 <= (status[10:8] == 2);
	end
end

reg ce_pix;
always @(posedge CLK_VIDEO) begin
	reg [2:0] div;
	reg       lores;

	div <= div + 1'b1;
	if(&div) lores <= ~lores;
	ce_pix <= (~lores | ~hq2x160) && !div;
end

wire scandoubler = status[10:8] || forced_scandoubler;

assign CLK_VIDEO = clk64;
assign VGA_SL    = (status[10:8] > 2) ? status[9:8] - 2'd2 : 2'd0;
assign VGA_F1    = 0;

reg [9:0] vcrop;
reg wide;
always @(posedge CLK_VIDEO) begin
	vcrop <= 0;
	wide <= 0;
	if(HDMI_WIDTH >= (HDMI_HEIGHT + HDMI_HEIGHT[11:1]) && !scandoubler) begin
		if(HDMI_HEIGHT == 480)  vcrop <= 240;
		if(HDMI_HEIGHT == 600)  begin vcrop <= 200; wide <= vcrop_en; end
		if(HDMI_HEIGHT == 720)  vcrop <= 240;
		if(HDMI_HEIGHT == 768)  vcrop <= 256; // NTSC mode has 250 visible lines only!
		if(HDMI_HEIGHT == 800)  begin vcrop <= 200; wide <= vcrop_en; end
		if(HDMI_HEIGHT == 1080) vcrop <= 10'd216;
		if(HDMI_HEIGHT == 1200) vcrop <= 240;
	end
	else if(HDMI_WIDTH >= 1440 && !scandoubler) begin
		// 1920x1440 and 2048x1536 are 4:3 resolutions and won't fit in the previous if statement ( width > height * 1.5 )
		if(HDMI_HEIGHT == 1440) vcrop <= 240;
		if(HDMI_HEIGHT == 1536) vcrop <= 256;
	end
end


wire [1:0] ar = status[5:4];
wire vcrop_en = status[32];
wire vga_de;
video_freak video_freak
(
	.*,
	.VGA_DE_IN(vga_de),
	.ARX((!ar) ? (wide ? 12'd340 : 12'd400) : (ar - 1'd1)),
	.ARY((!ar) ? 12'd300 : 12'd0),
	.CROP_SIZE(vcrop_en ? vcrop : 10'd0),
	.CROP_OFF(0),
	.SCALE(status[31:30])
);

wire freeze_sync;
reg freeze;
always @(posedge clk_sys) begin
	reg old_sync;
	
	old_sync <= freeze_sync;
	if(old_sync ^ freeze_sync) freeze <= OSD_STATUS & status[42];
end

assign HDMI_FREEZE = freeze;

video_mixer #(.GAMMA(1)) video_mixer
(
	.CLK_VIDEO(CLK_VIDEO),

	.hq2x(~status[10] & (status[9] ^ status[8])),
	.scandoubler(scandoubler),
	.gamma_bus(gamma_bus),

	.ce_pix(ce_pix),
	.R(r),
	.G(g),
	.B(b),
	.HSync(hsync_out),
	.VSync(vsync_out),
	.HBlank(hblank),
	.VBlank(vblank),

	.HDMI_FREEZE(HDMI_FREEZE),
	.freeze_sync(freeze_sync),

	.CE_PIXEL(CE_PIXEL),
	.VGA_R(VGA_R),
	.VGA_G(VGA_G),
	.VGA_B(VGA_B),
	.VGA_VS(VGA_VS),
	.VGA_HS(VGA_HS),
	.VGA_DE(vga_de)
);

wire        opl_en = status[12];
wire [15:0] opl_out;
wire  [7:0] opl_dout;
opl3 #(.OPLCLK(47291931)) opl_inst
(
	.clk(clk_sys),
	.clk_opl(clk48),
	.rst_n(reset_n & opl_en),

	.addr(c64_addr[4]),
	.dout(opl_dout),
	.we(ram_we & IOF & opl_en & c64_addr[6] & ~c64_addr[5]),
	.din(c64_data_out),

	.sample_l(opl_out)
);

reg ioe_we, iof_we;
always @(posedge clk_sys) begin
	reg old_ioe, old_iof;

	old_ioe <= IOE;
	ioe_we <= ~old_ioe & IOE & ram_we;

	old_iof <= IOF;
	iof_we <= ~old_iof & IOF & ram_we;
end

reg [11:0] sid_ld_addr = 0;
reg [15:0] sid_ld_data = 0;
reg        sid_ld_wr   = 0;
always @(posedge clk_sys) begin
	sid_ld_wr <= 0;
	if(ioctl_wr && load_flt && ioctl_addr < 6144) begin
		if(ioctl_addr[0]) begin
			sid_ld_data[15:8] <= ioctl_data;
			sid_ld_addr <= ioctl_addr[12:1];
			sid_ld_wr <= 1;
		end
		else begin
			sid_ld_data[7:0] <= ioctl_data;
		end
	end
end

//DigiMax
reg [8:0] dac_l, dac_r;
always @(posedge clk_sys) begin
	reg [8:0] dac[4];
	reg [3:0] act;

	if(!status[41:40] || ~reset_n) begin
		dac <= '{0,0,0,0};
		act <= 0;
	end
	else if((status[41] ? iof_we : ioe_we) && ~c64_addr[2]) begin
		dac[c64_addr[1:0]] <= c64_data_out;
		if(c64_data_out) act[c64_addr[1:0]] <= 1;
	end

	// guess mono/stereo/4-chan modes
	if(act<2) begin
		dac_l <= dac[0] + dac[0];
		dac_r <= dac[0] + dac[0];
	end
	else if(act<3) begin
		dac_l <= dac[1] + dac[1];
		dac_r <= dac[0] + dac[0];
	end
	else begin
		dac_l <= dac[1] + dac[2];
		dac_r <= dac[0] + dac[3];
	end
end

localparam [3:0] comp_f1 = 4;
localparam [3:0] comp_a1 = 2;
localparam       comp_x1 = ((32767 * (comp_f1 - 1)) / ((comp_f1 * comp_a1) - 1)) + 1; // +1 to make sure it won't overflow
localparam       comp_b1 = comp_x1 * comp_a1;

function [15:0] compr; input [15:0] inp;
	reg [15:0] v, v1;
	begin
		v  = inp[15] ? (~inp) + 1'd1 : inp;
		v1 = (v < comp_x1[15:0]) ? (v * comp_a1) : (((v - comp_x1[15:0])/comp_f1) + comp_b1[15:0]);
		v  = v1;
		compr = inp[15] ? ~(v-1'd1) : v;
	end
endfunction

reg [15:0] alo,aro;
always @(posedge clk_sys) begin
	reg [16:0] alm,arm;
	reg [15:0] cout;
	reg [15:0] cin;
	
	cin  <= opl_out - {{3{opl_out[15]}},opl_out[15:3]};
	cout <= compr(cin);

	alm <= {cout[15],cout} + {audio_l[17],audio_l[17:2]} + {2'b0,dac_l,6'd0} + {cass_snd, 9'd0};
	arm <= {cout[15],cout} + {audio_r[17],audio_r[17:2]} + {2'b0,dac_r,6'd0} + {cass_snd, 9'd0};
	alo <= ^alm[16:15] ? {alm[16], {15{alm[15]}}} : alm[15:0];
	aro <= ^arm[16:15] ? {arm[16], {15{arm[15]}}} : arm[15:0];
end

assign AUDIO_L = alo;
assign AUDIO_R = aro;
assign AUDIO_S = 1;
assign AUDIO_MIX = status[19:18];

//------------- TAP -------------------

wire       tap_download = ioctl_download & load_tap;
wire       tap_reset    = ~reset_n | tap_download | status[23] | !tap_last_addr | cass_finish | (cass_run & ((tap_last_addr - tap_play_addr) < 80));
wire       tap_loaded   = (tap_play_addr < tap_last_addr);                                    // ^^ auto-unload if motor stopped at the very end ^^
wire       tap_play_btn = status[7] | tape_play;
wire       tape_play;

reg [24:0] tap_play_addr;
reg [24:0] tap_last_addr;
reg  [1:0] tap_wrreq;
wire       tap_wrfull;
reg  [1:0] tap_version;
reg        tap_start;

always @(posedge clk_sys) begin
	reg io_cycleD;
	reg read_cyc;

	io_cycleD <= io_cycle;
	tap_wrreq <= tap_wrreq << 1;

	if(tap_reset) begin
		//C1530 module requires one more byte at the end due to fifo early check.
		tap_last_addr <= tap_download ? ioctl_addr+2'd2 : 25'd0;
		tap_play_addr <= 0;
		tap_start     <= ~status[39] & tap_download;
		read_cyc      <= 0;
	end
	else begin
		tap_start <= 0;
		if (~io_cycle & io_cycleD & ~tap_wrfull & tap_loaded) read_cyc <= 1;
		if (io_cycle & io_cycleD & read_cyc) begin
			tap_play_addr <= tap_play_addr + 1'd1;
			read_cyc <= 0;
			tap_wrreq[0] <= 1;
		end
	end
end

wire cass_write;
wire cass_motor;
wire cass_sense;
wire cass_read;
wire cass_run;
wire cass_finish;
wire cass_snd = cass_read & ~cass_run & status[11] & ~cass_finish;

c1530 c1530
(
	.clk32(clk_sys),
	.restart_tape(tap_reset),
	.wav_mode(0),
	.tap_version(tap_version),
	.host_tap_in(sdram_data),
	.host_tap_wrreq(tap_wrreq[1]),
	.tap_fifo_wrfull(tap_wrfull),
	.tap_fifo_error(cass_finish),
	.cass_read(cass_read),
	.cass_write(cass_write),
	.cass_motor(cass_motor),
	.cass_sense(cass_sense),
	.cass_run(cass_run),
	.osd_play_stop_toggle(tap_play_btn | tap_start),
	.ear_input(0)
);

reg use_tape;
always @(posedge clk_sys) begin
	integer to = 0;

	if(to) to <= to - 1;
	else use_tape <= status[36];

	if(tap_loaded | ~cass_sense) begin
		use_tape <= 1;
		to <= 128000000; //4s
	end
end

reg [26:0] act_cnt;
always @(posedge clk_sys) act_cnt <= act_cnt + (cass_sense ? 4'd1 : 4'd8);
wire tape_led = tap_loaded && (act_cnt[26] ? (~(~cass_sense & cass_motor) && act_cnt[25:18] > act_cnt[7:0]) : act_cnt[25:18] <= act_cnt[7:0]);

wire tape_adc, tape_adc_act;
ltc2308_tape #(.CLK_RATE(32000000)) ltc2308_tape
(
  .clk(clk_sys),
  .ADC_BUS(ADC_BUS),
  .dout(tape_adc),
  .active(tape_adc_act)
);

//------------- USER PORT -----------------

wire [7:0] pb_i, pb_o;
wire       pa2_i, pa2_o;
wire       pc2_n_o;
wire       flag2_n_i;
wire       sp2_i, sp2_o, sp1_o, sp1_i;
wire       cnt2_i, cnt2_o, cnt1_o, cnt1_i;

always_comb begin
	pa2_i       = 1;
	flag2_n_i   = 1;
	sp1_i       = 1;
	sp2_i       = 1;
	cnt1_i      = 1;
	cnt2_i      = 1;
	pb_i        = 8'hFF;
	UART_TXD    = 1;
	UART_RTS    = 0;
	UART_DTR    = 0;
	drive_par_i = 8'hFF;
	drive_stb_i = 1;
	USER_OUT[0] = 1;
	USER_OUT[1] = 1;

	if(disk_parport & disk_access) begin
		drive_par_i = pb_o;
		drive_stb_i = pc2_n_o;
		pb_i        = drive_par_o;
		flag2_n_i   = drive_stb_o;
	end
	else if(status[43]) begin
		UART_TXD  = pa2_o & uart_int;
		flag2_n_i = uart_rxd;
		sp2_i     = uart_rxd;
		pb_i[0]   = uart_rxd;
		UART_RTS  = ~pb_o[1] & uart_int;
		UART_DTR  = ~pb_o[2] & uart_int;
		pb_i[4]   = ~uart_dsr;
		pb_i[6]   = ~uart_cts;
		pb_i[7]   = ~uart_dsr;

		USER_OUT[1] = pa2_o | uart_int;

		if(~status[51]) begin
			UART_TXD = pa2_o & sp1_o & uart_int;
			pb_i[7]  = cnt2_o;
			cnt2_i   = pb_o[7];

			USER_OUT[1] = (pa2_o & sp1_o) | uart_int;
		end
	end
	else begin
		pb_i[5:0] = {!joyD_c64[6:4], !joyC_c64[6:4], pb_o[7] ? ~joyC_c64[3:0] : ~joyD_c64[3:0]};
	end
end

wire uart_int = ~status[33];

reg uart_rxd, uart_dsr, uart_cts;
always @(posedge clk_sys) begin
	reg rxd1, rxd2, dsr1, dsr2, cts1, cts2;

	rxd1 <= uart_int ? UART_RXD : USER_IN[0]; rxd2 <= rxd1; if(rxd1 == rxd2) uart_rxd <= rxd2;
	cts1 <= UART_CTS & uart_int; cts2 <= cts1; if(cts1 == cts2) uart_cts <= cts2;
	dsr1 <= UART_DSR & uart_int; dsr2 <= dsr1; if(dsr1 == dsr2) uart_dsr <= dsr2;
end

wire rtcF83_sda;
rtcF83 #(16000000, 0) rtcF83
(
	.clk(clk_sys),
	.ce(drive_ce),
	.reset(~reset_n | use_tape),
	.RTC(RTC),
	.scl_i(cass_write),
	.sda_i(cass_motor),
	.sda_o(rtcF83_sda)
);

reg use_rtc = 0;
always @(posedge clk_sys) begin
	reg [20:0] to = 0;

	if(to) to <= to - 1'd1;
	use_rtc <= |to;

	if(cass_write) to <= '1;
end

wire cass_rtc = ~(rtcF83_sda & use_rtc & cass_motor);

endmodule