Soundcore compiles

[fpgaboy.git] / Sound1.v

diff --git a/Sound1.v b/Sound1.v
new file mode 100644 (file)
index 0000000..9444dbf
--- /dev/null
+++ b/Sound1.v
@@ -0,0 +1,79 @@
+`define ADDR_NR10 16'hFF10
+`define ADDR_NR11 16'hFF11
+`define ADDR_NR12 16'hFF12
+`define ADDR_NR13 16'hFF13
+`define ADDR_NR14 16'hFF14
+
+module Sound1(
+       input core_clk,
+       input wr,
+       input rd,
+       input [15:0] addr,
+       inout [7:0] data,
+       input cntclk,
+       input lenclk,
+       input en,
+       output [3:0] snd_data
+       );
+
+       /* can be optimized as register file */
+       reg [7:0] nr10, nr11, nr12, nr13, nr14;
+       reg [10:0] counter = 0;
+       reg [4:0] lencnt = 0;
+       reg [3:0] delta = 4'b1111;
+       reg [2:0] dutycnt;
+       reg [3:0] snd_out = 0;
+
+       assign snd_data = en ? snd_out : 0;
+
+       assign data = rd ?
+                        addr == `ADDR_NR10 ? nr10 :
+                        addr == `ADDR_NR11 ? nr11 :
+                        addr == `ADDR_NR12 ? nr12 :
+                        addr == `ADDR_NR13 ? nr13 :
+                        addr == `ADDR_NR14 ? nr14 : 8'bzzzzzzzz
+                     : 8'bzzzzzzzz;
+
+       always @ (negedge core_clk) begin
+               if(en && wr) begin
+                       case(addr)
+                       `ADDR_NR10: nr10 <= data;
+                       `ADDR_NR11: nr11 <= data;
+                       `ADDR_NR12: nr12 <= data;
+                       `ADDR_NR13: nr13 <= data;
+                       `ADDR_NR14: nr14 <= data;
+                       endcase
+               end
+               else if(!en) begin
+                       nr10 <= 8'h80;
+                       nr11 <= 8'h3F;
+                       nr12 <= 8'h00;
+                       nr13 <= 8'hFF;
+                       nr14 <= 8'hBF;
+               end
+       end
+
+       always @ (posedge cntclk) begin
+               if(counter)
+                       counter <= counter - 1;
+               else begin
+                       counter <= ~{nr14[2:0],nr13} + 1;  /* possible A */
+                       dutycnt <= dutycnt + 1;
+               end
+
+               case (nr11[7:6])
+               2'b00: snd_out <= dutycnt ? 0 : delta;   /* probable A */
+               2'b01: snd_out <= (dutycnt[2:1] == 2'b0) ? delta : 0;
+               2'b10: snd_out <= dutycnt[2] ? delta : 0;
+               2'b11: snd_out <= (dutycnt[2:1] == 2'b0) ? 0 : delta;
+               endcase
+       end
+
+       always @ (posedge lenclk) begin
+               if(lencnt)
+                       lencnt <= lencnt - 1;            /* possible A */
+               else
+                       lencnt <= ~nr11[4:0] + 1;
+       end
+
+endmodule