Merge pull request #36 from brNX/master

Game Genie Codes Support

Gameboy.qsf

@@ -351,6 +351,7 @@ set_location_assignment PIN_W20 -to SW[3]
 
 set_global_assignment -name PRE_FLOW_SCRIPT_FILE "quartus_sh:sys/build_id.tcl"
 
+set_global_assignment -name SYSTEMVERILOG_FILE gamegenie.sv
 set_global_assignment -name CDF_FILE jtag.cdf
 set_global_assignment -name QIP_FILE sys/sys.qip
 set_global_assignment -name QIP_FILE t80/T80.qip

Gameboy.sv

@@ -147,6 +147,8 @@ localparam CONF_STR1 = {
 	"OEF,System,Auto,Gameboy,Gameboy Color;",
 	"-;",
 	"OC,Inverted color,No,Yes;",
+	"FC,GG,Game Genie Code;",
+	"OH,Game Genie,ON,OFF;",
 	"O1,Palette,Grayscale,Custom;"
 };
 
@@ -250,9 +252,11 @@ hps_io #(.STRLEN(($size(CONF_STR1)>>3) + ($size(CONF_STR2)>>3) + ($size(CONF_STR
 ///////////////////////////////////////////////////
 
 wire cart_download = ioctl_download && (filetype == 8'h01 || filetype == 8'h41 || filetype == 8'h80);
-wire palette_download = ioctl_download && (filetype == 8'h05 || filetype == 8'h00);
+wire palette_download = ioctl_download && (filetype == 8'h07 || filetype == 8'h00);
 wire bios_download = ioctl_download && (filetype == 8'h40);
 
+wire type_gg = filetype == 8'h04;
+
 wire  [1:0] sdram_ds = cart_download ? 2'b11 : {cart_addr[0], ~cart_addr[0]};
 wire [15:0] sdram_do;
 wire [15:0] sdram_di = cart_download ? ioctl_dout : 16'd0;
@@ -527,6 +531,7 @@ gb gb (
 	.reset	    ( reset      ),
 	.clk         ( clk_cpu    ),   // the whole gameboy runs on 4mhnz
 	.clk2x       ( clk_cpu2x  ),   // ~8MHz in dualspeed mode (GBC)
+	.new_game_load  ( cart_download),
 
 	.fast_boot   ( 0          ),
 	.joystick    ( joystick   ),
@@ -553,7 +558,10 @@ gb gb (
 	.lcd_data    ( lcd_data   ),
 	.lcd_mode    ( lcd_mode   ),
 	.lcd_on      ( lcd_on     ),
-	.speed       ( speed      )
+	.speed       ( speed      ),
+	
+	.gg              (status[17]),
+	.gg_code         (gg_code)
 );
 
 // the lcd to vga converter
@@ -634,6 +642,29 @@ dpram_dif #(12,8,11,16) boot_rom_gbc (
 	.q_b ()
 );
 
+/////////////////////////  GAME GENIE //////////////////////////////////
+
+reg [34:0] gg_code;
+
+// Code layout:
+// {clock bit, enable, compare enable, 15'b address, 8'b compare, 8'b replace}
+//  34         33      32              31:16         15:8         7:0
+reg [3:0] old_ioctl_addr;
+always_ff @(posedge clk_sys) begin
+	gg_code[34] <= 1'b0;
+	old_ioctl_addr <= ioctl_addr[3:0];
+	gg_code[34] <= 1'b0;
+
+	if (ioctl_download && type_gg) begin
+		case (ioctl_addr[3:0])
+			0:  gg_code[32]    <= ioctl_dout[0];   // Compare Enable
+			4:  gg_code[31:16] <= ioctl_dout;      // Address
+			8:  gg_code[15:8]  <= ioctl_dout[7:0]; // compare byte
+			12: gg_code[7:0]   <= ioctl_dout[7:0]; // replace byte
+			14: gg_code[34]    <=  1'b1;           // Clock it in
+		endcase
+	end
+end
 
 /////////////////////////  BRAM SAVE/LOAD  /////////////////////////////
 

gamegenie.sv

@@ -0,0 +1,86 @@
+// NES Game Genie handling by Kitrinx
+// Apr 21, 2019
+
+// Code layout:
+// {clock bit, enable, compare enable, 15'b address, 8'b compare, 8'b replace}
+//  34         33      32              31:16         15:8         7:0
+
+localparam MAX_CODES = 32;
+
+module geniecodes(
+	input         clk,
+	input         reset,
+	input         enable,
+	input  [15:0] addr_in,
+	input   [7:0] data_in,
+	input  [37:0] code,
+	output        genie_ovr,
+	output  [7:0] genie_data
+);
+
+reg [33:0] codes[MAX_CODES];
+
+// If MAX_INDEX is changes, these need to be made larger
+wire [4:0] index, dup_index;
+reg [4:0] next_index;
+wire found_dup;
+
+assign index = found_dup ? dup_index : next_index;
+
+// See if the code exists already, so it can be disabled if loaded again
+always_comb begin
+	int x;
+	dup_index = 0;
+	found_dup = 0;
+
+	for (x = 0; x < MAX_CODES; x = x + 1'b1) begin
+		if (codes[x][31:16] == code[31:16]) begin
+			dup_index = x[4:0];
+			found_dup = 1'b1;
+		end
+	end
+end
+
+reg code_change;
+always_ff @(posedge clk) begin
+	int x;
+	if (reset) begin
+		next_index <= 0;
+		code_change <= 0;
+		for (x = 0; x < MAX_CODES; x = x + 1) codes[x] <= 34'd0;
+	end else begin
+		code_change <= code[34];
+		if (code[34] & ~code_change) begin // detect posedge
+			// Disable the code if it's the exact same code loaded again, otherwise, 
+			// replace it enabled if it has the same address, otherwise, add a new code
+			codes[index] <= found_dup ? ((codes[index][15:0] == code[15:0]) ? {codes[index][33] ? 1'b0 : 1'b1, code[32:0]} : {1'b1, code[32:0]}) : {1'b1, code[32:0]};
+			if (~found_dup) next_index <= next_index + 1'b1;
+		end
+	end
+end
+
+always_comb begin
+	int x;
+	genie_ovr = 1'b0;
+	genie_data = 8'd0;
+	x = 0;
+
+	if (enable) begin
+		for (x = 0; x < MAX_CODES; x = x + 1'b1) begin
+			if (codes[x][33] && codes[x][31:16] == addr_in) begin
+				if (codes[x][32]) begin        // Check for compare bit if needed
+					if (codes[x][15:8] == data_in) begin
+						genie_ovr = 1'b1;
+						genie_data = codes[x][7:0];
+					end
+				end else begin                 // Otherwise just match
+					genie_ovr = 1'b1;
+					genie_data = codes[x][7:0];
+				end
+			end
+		end
+	end
+end
+
+
+endmodule

gb.v

@@ -21,6 +21,7 @@
 
 module gb (
    input reset,
+	input new_game_load,
    input clk,
    input clk2x,
 
@@ -51,7 +52,10 @@ module gb (
 	output [1:0] lcd_mode,
 	output lcd_on,
 	
-	output speed   //GBC
+	output speed,   //GBC
+	
+	input         gg,
+	input  [34:0] gg_code
 );
 
 // include cpu
@@ -151,11 +155,31 @@ GBse cpu (
    .HALT_n     (               ),
    .BUSAK_n    (               ),
    .A          ( cpu_addr      ),
-   .DI         ( cpu_di        ),
+   .DI         ( genie_ovr ? genie_data : cpu_di),
    .DO         ( cpu_do        ),
 	.STOP       ( cpu_stop      )
 );
 
+// --------------------------------------------------------------------
+// --------------------------- Game Genie -----------------------------
+// --------------------------------------------------------------------
+
+wire genie_ovr;
+wire [7:0] genie_data;
+
+
+geniecodes codes (
+	.clk        (clk2x),
+	.reset      (new_game_load),
+	.enable     (~gg),
+	.addr_in    (cpu_addr),
+	.data_in    (cpu_di),
+	.code       (gg_code),
+	.genie_ovr  (genie_ovr),
+	.genie_data (genie_data)
+);
+
+
 // --------------------------------------------------------------------
 // --------------------- Speed Toggle KEY1 (GBC)-----------------------
 // --------------------------------------------------------------------