SummerCart64/fw/rtl/address_decoder.v
2020-10-11 00:32:00 +02:00

45 lines
1.3 KiB
Verilog

module address_decoder (
input [31:0] i_address,
output o_cart_config,
output o_flash,
output o_flash_cfg,
output o_sdram,
output o_eeprom,
input i_flash_enable,
input i_sdram_enable,
input i_eeprom_pi_enable,
output o_address_valid
);
localparam CART_CONFIG_ADDR = 32'h1E00_0000;
localparam CART_CONFIG_WIDTH = 8;
assign o_cart_config = i_address[31:CART_CONFIG_WIDTH] == CART_CONFIG_ADDR[31:CART_CONFIG_WIDTH];
localparam FLASH_ADDR = 32'h1000_0000;
localparam FLASH_REMAP_ADDR = 32'h1800_0000;
localparam FLASH_WIDTH = 24;
assign o_flash = i_flash_enable && (i_address[31:FLASH_WIDTH] == (i_sdram_enable ? FLASH_REMAP_ADDR[31:FLASH_WIDTH] : FLASH_ADDR[31:FLASH_WIDTH]));
localparam FLASH_CFG_ADDR = 32'h1C00_0000;
assign o_flash_cfg = i_flash_enable && (i_address == FLASH_CFG_ADDR);
localparam SDRAM_ADDR = 32'h1000_0000;
localparam SDRAM_WIDTH = 26;
assign o_sdram = i_sdram_enable && (i_address[31:SDRAM_WIDTH] == SDRAM_ADDR[31:SDRAM_WIDTH]);
localparam EEPROM_ADDR = 32'h1D00_0000;
localparam EEPROM_WIDTH = 11;
assign o_eeprom = i_eeprom_pi_enable && (i_address[31:EEPROM_WIDTH] == EEPROM_ADDR[31:EEPROM_WIDTH]);
assign o_address_valid = (|{o_cart_config, o_flash, o_flash_cfg, o_sdram, o_eeprom});
endmodule