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module GxROM # (parameter MIRRORING_VERTICAL = 1)
(
output led,
input m2,
input romsel,
input cpu_rw_in,
output [18:12] cpu_addr_out,
input [14:0] cpu_addr_in,
input [7:0] cpu_data_in,
output cpu_wr_out,
output cpu_rd_out,
output cpu_flash_ce,
output cpu_sram_ce,
input ppu_rd_in,
input ppu_wr_in,
input [13:10] ppu_addr_in,
output [18:10] ppu_addr_out,
output ppu_rd_out,
output ppu_wr_out,
output ppu_flash_ce,
output ppu_sram_ce,
output ppu_ciram_a10,
output ppu_ciram_ce,
output irq
);
reg [1:0] prg_bank;
reg [1:0] chr_bank;
assign led = ~romsel;
assign cpu_addr_out[18:12] = {prg_bank, cpu_addr_in[14:12]};
assign cpu_wr_out = 1;
assign cpu_rd_out = ~cpu_rw_in;
assign cpu_flash_ce = romsel;
assign cpu_sram_ce = 1;
assign ppu_addr_out[18:10] = {chr_bank, ppu_addr_in[12:10]};
assign ppu_rd_out = ppu_rd_in;
assign ppu_wr_out = ppu_wr_in;
assign ppu_flash_ce = ppu_addr_in[13];
assign ppu_sram_ce = 1;
assign ppu_ciram_a10 = MIRRORING_VERTICAL ? ppu_addr_in[10] : ppu_addr_in[11];
assign ppu_ciram_ce = ~ppu_addr_in[13];
assign irq = 1'bz;
always @ (posedge romsel)
begin
if (cpu_rw_in == 0)
begin
chr_bank = cpu_data_in[1:0];
prg_bank = cpu_data_in[5:4];
end
end
endmodule
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