Super Game Boy multiplayer support

Gameboy.sv

@@ -215,8 +215,8 @@ wire [24:0] ioctl_addr;
 wire [15:0] ioctl_dout;
 reg         ioctl_wait;
 
-wire [15:0] joystick_0, joystick_1;
-wire [15:0] joystick = joystick_0 | joystick_1;
+wire [15:0] joystick_0, joystick_1, joystick_2, joystick_3;
+
 wire [7:0]  filetype;
 
 reg  [31:0] sd_lba;
@@ -266,7 +266,9 @@ hps_io #(.STRLEN($size(CONF_STR)>>3), .WIDE(1)) hps_io
 	.forced_scandoubler(forced_scandoubler),
 
 	.joystick_0(joystick_0),
-	.joystick_1(joystick_1)
+	.joystick_1(joystick_1),
+	.joystick_2(joystick_2),
+	.joystick_3(joystick_3)
 );
 
 ///////////////////////////////////////////////////
@@ -561,12 +563,12 @@ gb gb (
 	.ce_2x       ( ce_cpu2x   ),   // ~8MHz in dualspeed mode (GBC)
 	
 	.fast_boot   ( status[2]  ),
-	.joystick    ( joystick   ),
+
 	.isGBC       ( isGBC      ),
 	.isGBC_game  ( isGBC_game ),
 
-	.joy_p54     (joy_p54     ),
-	.joy_sgb     (joy_do_sgb  ),
+	.joy_p54     ( joy_p54     ),
+	.joy_din     ( joy_do_sgb  ),
 
 	// interface to the "external" game cartridge
 	.cart_addr   ( cart_addr  ),
@@ -652,7 +654,8 @@ lcd lcd
 	.v_cnt  ( v_cnt      )
 );
 
-wire [5:0] joy_p54, joy_do_sgb;
+wire [1:0] joy_p54;
+wire [3:0] joy_do_sgb;
 wire [14:0] sgb_lcd_data;
 wire [15:0] sgb_border_pix;
 wire sgb_lcd_clkena, sgb_lcd_on;
@@ -668,7 +671,11 @@ sgb sgb (
 	.clk_vid     ( CLK_VIDEO   ),
 	.ce_pix      ( ce_pix      ),
 
-	.joy_di      ( joy_p54     ),
+	.joystick_0  ( joystick_0  ),
+	.joystick_1  ( joystick_1  ),
+	.joystick_2  ( joystick_2  ),
+	.joystick_3  ( joystick_3  ),
+	.joy_p54     ( joy_p54     ),
 	.joy_do      ( joy_do_sgb  ),
 
 	.sgb_en      ( ~sgb_en[1] & isSGB_game & ~isGBC ),

rtl/gb.v

@@ -53,8 +53,8 @@ module gb (
 	output [1:0] lcd_mode,
 	output lcd_on,
 
-	output [5:0] joy_p54,
-	input  [5:0] joy_sgb,
+	output [1:0] joy_p54,
+	input  [3:0] joy_din,
 	
 	output speed,   //GBC
 	
@@ -329,8 +329,6 @@ end
 // ------------------------------ inputs ------------------------------
 // --------------------------------------------------------------------
 
-wire [3:0] joy_p4 = ~{ joystick[2], joystick[3], joystick[1], joystick[0] } | {4{p54[0]}};
-wire [3:0] joy_p5 = ~{ joystick[7], joystick[6], joystick[5], joystick[4] } | {4{p54[1]}};
 reg  [1:0] p54;
 
 always @(posedge clk_cpu) begin
@@ -338,8 +336,8 @@ always @(posedge clk_cpu) begin
 	else if(sel_joy && !cpu_wr_n)	p54 <= cpu_do[5:4];
 end
 
-wire [7:0] joy_do = { 2'b11, joy_sgb };
-assign joy_p54 = {p54, joy_p4 & joy_p5};
+wire [7:0] joy_do = { 2'b11, p54, joy_din };
+assign joy_p54 = p54;
 
 // --------------------------------------------------------------------
 // ---------------------------- interrupts ----------------------------
@@ -362,7 +360,7 @@ wire [7:0] irq_vec =
 
 //wire vs = (lcd_mode == 2'b01);
 //reg vsD, vsD2;
-reg [7:0] inputD, inputD2;
+reg [3:0] inputD, inputD2;
 
 // irq is low when an enable irq is active
 wire irq_n = !(ie_r & if_r);
@@ -397,7 +395,8 @@ always @(negedge clk_cpu) begin //negedge to trigger interrupt earlier
 	if(~old_serial_irq & serial_irq) if_r[3] <= 1'b1;
 
 	// falling edge on any input line P10..P13
-	inputD <= {joy_p4, joy_p5};
+
+	inputD <= joy_din;
 	inputD2 <= inputD;
 	if(~inputD & inputD2) if_r[4] <= 1'b1;
 

rtl/sgb.v

@@ -17,8 +17,13 @@ module sgb (
 	input [8:0]  h_cnt,
 	input [8:0]  v_cnt,
 
-	input [5:0]  joy_di,
-	output [5:0] joy_do,
+	input [7:0]  joystick_0,
+	input [7:0]  joystick_1,
+	input [7:0]  joystick_2,
+	input [7:0]  joystick_3,
+
+	input [1:0]  joy_p54,
+	output [3:0] joy_do,
 
 	output reg [15:0] sgb_border_pix,
 
@@ -46,10 +51,10 @@ localparam CMD_ATTR_TRN = 5'h15;
 localparam CMD_ATTR_SET = 5'h16;
 localparam CMD_MASK_EN  = 5'h17;
 
-assign joy_do = joypad_id_out ? {joy_di[5:4],2'b11,joypad_id} : joy_di;
 
-wire p14 = joy_di[4];
-wire p15 = joy_di[5];
+
+wire p14 = joy_p54[0];
+wire p15 = joy_p54[1];
 
 reg old_p15, old_p14;
 reg [7:0] data;
@@ -330,6 +335,7 @@ end
   2 player: 0F,0E. 4 player: 0F,0E,0D,0C
   Normal Gameboy or Super Gameboy with multiplayer disabled will always return 0F.
 */
+
 reg [1:0] joypad_id;
 reg joypad_id_out;
 reg joylock;
@@ -357,6 +363,19 @@ always @(posedge clk_sys) begin
 
 end
 
+assign joy_do = joypad_id_out ? {2'b11,joypad_id} : joy_data;
+
+wire [3:0] joy_dir     = ~{ joystick[2], joystick[3], joystick[1], joystick[0] } | {4{p14}};
+wire [3:0] joy_buttons = ~{ joystick[7], joystick[6], joystick[5], joystick[4] } | {4{p15}};
+wire [3:0] joy_data = joy_dir & joy_buttons;
+
+wire [7:0] joystick =
+				(~sgb_en | ~mlt_ctrl[0]) ? (joystick_0 | joystick_1) :
+				(joypad_id == 2'b11) ? joystick_0 :
+				(joypad_id == 2'b10) ? joystick_1 :
+				(joypad_id == 2'b01) ? joystick_2 :
+				                       joystick_3;
+
 wire lcd_off = !lcd_on || (lcd_mode == 2'd01);
 reg old_lcd_off;