Sound: Leave it to Dennis.

[fpgaboy.git] / Soundcore.v

`define ADDR_NR50 16'hFF24
`define ADDR_NR51 16'hFF25
`define ADDR_NR52 16'hFF26

module Soundcore(
	input core_clk,
	input wr,
	input rd,
	input [15:0] addr,
	inout [7:0] data,
	output reg snd_data_l,
	output reg snd_data_r
	);

	reg [7:0] nr50,nr51,nr52;
	reg [3:0] pwmcnt;
	reg [4:0] cntclk;
	reg [13:0] lenclk;
	wire [3:0] sndout1,sndout2,sndout3,sndout4;
	wire [3:0] right_snd =
		(nr51[0] ? sndout1 : 4'b0) +
		(nr51[1] ? sndout2 : 4'b0) +
		(nr51[2] ? sndout3 : 4'b0) +
		(nr51[3] ? sndout4 : 4'b0);
	wire [3:0] left_snd =
		(nr51[4] ? sndout1 : 4'b0) +
		(nr51[5] ? sndout2 : 4'b0) +
		(nr51[6] ? sndout3 : 4'b0) +
		(nr51[7] ? sndout4 : 4'b0);
	assign sndout3 = 0;
	assign sndout4 = 0;

	assign data = rd ?
	                 addr == `ADDR_NR50 ? nr50 :
	                 addr == `ADDR_NR51 ? nr51 :
	                 addr == `ADDR_NR52 ? nr52 : 8'bzzzzzzzz
		      : 8'bzzzzzzzz;

	always @ (negedge core_clk) begin
		if(wr) begin
			case(addr)
			`ADDR_NR50: nr50 <= data;
			`ADDR_NR51: nr51 <= data;
			`ADDR_NR52: nr52 <= {data[7],7'b1111111};
			endcase
		end
		cntclk <= cntclk + 1;
		lenclk <= lenclk + 1;
		pwmcnt <= pwmcnt + 1; 
		snd_data_l <= (pwmcnt <= left_snd) ? nr50[7] : 0;
		snd_data_r <= (pwmcnt <= right_snd) ? nr50[3] : 0;
	end

	Sound1 s1(
		.core_clk(core_clk),
		.wr(wr),
		.rd(rd),
		.addr(addr),
		.data(data),
		.cntclk(cntclk[4]),
		.lenclk(lenclk[13]),
		.en(nr52[7]),
		.snd_data(sndout1)
	);
	
	Sound2 s2(
		.core_clk(core_clk),
		.wr(wr),
		.rd(rd),
		.addr(addr),
		.data(data),
		.cntclk(cntclk[4]),
		.lenclk(lenclk[13]),
		.en(nr52[7]),
		.snd_data(sndout2)
	);

endmodule