1 files changed, 129 insertions, 0 deletions
diff --git a/Mapper/WarfaceMapper.v b/Mapper/WarfaceMapper.v
new file mode 100644
index 0000000..4a71b05
--- /dev/null
+++ b/Mapper/WarfaceMapper.v
@@ -0,0 +1,129 @@
+module WarfaceMapper
+(
+   input m2,
+	input romsel,
+	input cpu_rw,
+	input ppu_rd,
+	input ppu_wr,
+	
+	input cpu_a0,
+	input cpu_a13,
+	input cpu_a14,
+	input [7:0] cpu_data,
+	output [16:13] prg_addr,
+	output prg_ce,
+	output prg_oe,
+	output prg_prog,
+	
+	input [13:10] ppu_addr,
+	output [16:10] chr_addr,
+	output chr_ce,
+	output chr_oe,
+	output chr_prog,	
+	
+	output ciram_a10,	
+	output irq
+);
+
+// scanline counter, counts dummy PPU reads, detects v-blank automatically
+reg [3:0] ppu_rd_hi_time = 0;       // counts how long there is no reads from PPU to detect v-blank
+reg [1:0] ppu_nt_read_count;        // nametable read counter
+reg [7:0] scanline = 0;             // current scanline
+reg new_screen = 0;                 // stores 1 when v-blank detected ("in frame" flag)
+reg new_screen_clear = 0;           // flag to clear new_screen flag
+
+assign prg_ce = romsel;
+assign prg_oe = romsel | !cpu_rw;
+assign prg_prog = romsel | cpu_rw;
+
+reg [2:0] prg_bank;
+assign prg_addr = cpu_a14 
+	? {3'b111, cpu_a13} // fixed last bank @ $C000-$FFFF
+	: {prg_bank, cpu_a13}; // selectable @ $8000-$BFFF
+
+assign chr_ce = ppu_addr[13];
+assign chr_oe = ppu_addr[13] | ppu_rd;
+assign chr_prog = ppu_addr[13] | ppu_wr;
+
+reg prg_auto_switch = 0;
+reg [4:0] chr_bank;
+reg [1:0] chr_latch;
+assign chr_addr[16:10] = !ppu_addr[12] 
+	? (
+	   prg_auto_switch
+		? {chr_bank[4:2], chr_latch[1:0], ppu_addr[11:10]} // $0000-$0FFF is autoswitchable
+		: {chr_bank[4:0], ppu_addr[11:10]} // $0000-$0FFF is switchable manually
+	)
+	: {5'b11111, ppu_addr[11:10]}; // $1000-$1FFF is fixed to last
+
+assign ciram_a10 = ppu_addr[10]; // horizontal mirroring
+
+reg [11:0] timer = 0;
+reg timer_elapsed = 0;
+assign irq = timer_elapsed ? 1'b0 : 1'bZ;
+
+always @ (negedge m2)
+begin
+  if (timer > 0)
+  begin
+    timer = timer - 1;
+	 if (timer == 0) timer_elapsed = 1;
+  end
+  if (!romsel && !cpu_rw && cpu_a13 && cpu_a14) // write to $6000-$7FFF
+  begin
+    if (!cpu_a0)
+	 begin // even
+	   prg_bank[2:0] = cpu_data[2:0];
+	   if (cpu_data[7]) timer = 4095;
+		timer_elapsed = 0;
+	 end else begin // odd
+	   prg_auto_switch = cpu_data[7];
+		chr_bank[4:0] = cpu_data[4:0];
+	 end
+  end 
+end
+
+// V-blank detector  
+always @ (negedge m2, negedge ppu_rd)
+begin
+   if (~ppu_rd)
+   begin
+      ppu_rd_hi_time = 0;
+      if (new_screen_clear) new_screen = 0;
+   end else if (ppu_rd_hi_time < 4'b1111)
+   begin
+      // Counting how long there is no PPU reads
+      ppu_rd_hi_time = ppu_rd_hi_time + 1'b1;
+   end else begin
+      // Too long, v-blank detected
+      new_screen = 1;
+   end
+end   
+
+// Scanline counter
+always @ (negedge ppu_rd)
+begin 
+   if (!new_screen && new_screen_clear) new_screen_clear = 0;
+   if (new_screen & !new_screen_clear)
+   begin
+      scanline = 0;        
+      new_screen_clear = 1;
+      chr_latch = 0;
+   end else 
+   if (ppu_addr[13:12] == 2'b10)
+   begin
+      if (ppu_nt_read_count < 3)
+      begin
+         ppu_nt_read_count = ppu_nt_read_count + 1'b1;
+      end else begin
+         scanline = scanline + 1'b1;
+			if (scanline == 64) chr_latch = 1;
+			if (scanline == 128) chr_latch = 2;
+			if (scanline == 192) chr_latch = 3;
+      end
+   end else begin
+      ppu_nt_read_count = 0;
+   end
+end
+
+endmodule
+\ No newline at end of file