Merge branch 'master' into 'master'

Add header parsing for Genesis, ROM size autodetection, checksum validation.

See merge request InfiniteNesLives/INL-retro-progdump!23

host/scripts/sega/genesis_v1.lua

@@ -14,6 +14,22 @@ local function unsupported(operation)
 	print("\nUNSUPPORTED OPERATION: \"" .. operation .. "\" not implemented yet for Sega Genesis.\n")
 end
 
+-- Compute Genesis checksum from a file, which can be compared with header value.
+local function checksum_rom(filename)
+	local file = assert(io.open(filename, "rb"))
+	local sum = 0
+	-- Skip header
+	file:read(0x200)
+	while true do
+		-- Add up remaining 16-bit words
+		local bytes = file:read(2)
+		if not bytes then break end
+		sum = sum + string.unpack(">i2", bytes)
+	end
+	-- Only use the lower bits.
+	return sum & 0xFFFF
+end
+
 --/ROMSEL is always low for this dump
 local function dump_rom( file, rom_size_KB, debug )
 
@@ -30,6 +46,9 @@ local function dump_rom( file, rom_size_KB, debug )
 
 		-- A "large" Genesis ROM is 24 banks, many are 8 and 16 - status every 4 is reasonable.
 		-- The largest published Genesis game is Super Street Fighter 2, which is 40 banks!
+		-- TODO: Accessing banks in games that are >4MB require using a mapper.
+		-- See: https://plutiedev.com/beyond-4mb
+
 		if (read_count % 4 == 0) then
 			print("dumping ROM bank: ", read_count, " of ", num_reads - 1)
 		end
@@ -45,6 +64,121 @@ local function dump_rom( file, rom_size_KB, debug )
 
 end
 
+-- Helper to extract fields in internal header.
+local function extract_field_from_string(data, start_offset, length)
+	-- 1 is added to Offset to handle lua strings being 1-based.
+	return string.sub(data, start_offset + 1, start_offset + length)
+end
+
+-- Populates table with internal header contents from dumped data.
+local function extract_header(header_data)
+	-- https://plutiedev.com/rom-header
+	-- https://en.wikibooks.org/wiki/Genesis_Programming#ROM_header
+	
+	-- TODO: Decode publisher from t-series in build field
+	-- https://segaretro.org/Third-party_T-series_codes
+
+	local addr_console_name 		= 0x100
+	local addr_build_date 			= 0x110
+	local addr_domestic_name 		= 0x120
+	local addr_intl_name 			= 0x150
+	local addr_type_serial_version 	= 0x180
+	local addr_checksum 			= 0x18E
+	local addr_device_support 		= 0x190
+	local addr_rom_addr_range 		= 0x1A0
+	local addr_ram_addr_range 		= 0x1A8
+	local addr_sram_support 		= 0x1B0
+	local addr_modem_support 		= 0x1BC
+	local addr_region_support 		= 0x1F0
+
+	local len_console_name = 16
+	local len_build_date = 16
+	local len_name = 48
+	local len_type_serial_version = 14
+	local len_checksum = 2
+	local len_device_support = 16
+	local len_addr_range = 8
+	local len_sram_support = 12
+	local len_modem_support = 12
+	local len_region_support = 3
+
+	local header = {
+		console_name = extract_field_from_string(header_data, addr_console_name, len_console_name),
+		-- TODO: Decode T-Value and build info.
+		build_date = extract_field_from_string(header_data, addr_build_date, len_build_date),
+		domestic_name = extract_field_from_string(header_data, addr_domestic_name, len_name),
+		international_name = extract_field_from_string(header_data, addr_intl_name, len_name),
+		-- TODO: Decode Type, serial and revision.
+		type_serial_version = extract_field_from_string(header_data, addr_type_serial_version, len_type_serial_version),
+		checksum = string.unpack(">i2", extract_field_from_string(header_data, addr_checksum, len_checksum)), 
+		-- TODO: Decode device support.
+		io_device_support = extract_field_from_string(header_data, addr_device_support, len_device_support),
+		-- TODO: Decode SRAM support.
+		sram_support = extract_field_from_string(header_data, addr_sram_support, len_sram_support),
+		-- TODO: Decode modem support.
+		modem_support = extract_field_from_string(header_data, addr_modem_support, len_modem_support),
+		-- TODO: Decode region support.
+		region_support = extract_field_from_string(header_data, addr_region_support, len_region_support),
+	}
+	-- ROM range can be used to autodetect the rom size.
+	local rom_range = extract_field_from_string(header_data, addr_rom_addr_range, len_addr_range)
+	local rom_start = string.unpack(">i4", string.sub(rom_range, 1, 4))
+	local rom_end = string.unpack(">i4", string.sub(rom_range,5, 8))
+	header["rom_size"] = (rom_end - rom_start + 1) / 1024
+
+	-- These should be the same in every cart according to docs, but decode in case its not. (64 Kb)
+	local ram_range = extract_field_from_string(header_data, addr_ram_addr_range, len_addr_range)
+	local ram_start = string.unpack(">i4", string.sub(ram_range, 1, 4))
+	local ram_end = string.unpack(">i4", string.sub(ram_range,5, 8))
+	header["ram_size"] = (ram_end - ram_start + 1) / 1024
+	
+	return header
+end
+
+-- Make a human-friendly text representation of ROM Size.
+local function str_rom_size(rom_size_kb)
+	local mbit = rom_size_kb / 128
+	if mbit < 1 then
+		mbit = "<1"
+	end
+	return "" .. rom_size_kb .. " kB (".. mbit .." mbit)" 
+end
+
+-- Prints parsed header contents to stdout.
+local function print_header(genesis_header)
+	print("Console Name: \t" .. genesis_header["console_name"])
+	print("Domestic Name: \t" .. genesis_header["domestic_name"])
+	print("Release Date: \t" .. genesis_header["build_date"])
+	print("Rom Size: \t" .. str_rom_size(genesis_header["rom_size"]))
+	print("Serial/Version: " .. genesis_header["type_serial_version"])
+	print("Checksum: \t" .. hexfmt(genesis_header["checksum"]))
+end
+
+-- Reads and parses internal ROM header from first page of data.
+local function read_header()
+	dict.sega("SET_BANK", 0)
+
+	local page0_data = ""
+	dump.dumptocallback(
+		function (data)
+			page0_data = page0_data .. data
+		end,
+		64, 0x0000, "GENESIS_ROM_PAGE0", false
+	)
+	local header_data = string.sub(page0_data, 1, 0x201)
+	local genesis_header = extract_header(header_data)
+	return genesis_header
+end
+
+-- Test that cartridge is readable by looking for valid entries in internal header.
+local function test(genesis_header)
+	local valid = false
+	-- Trailing spaces are required! Field length is 16 characters.
+	if genesis_header["console_name"] == "SEGA GENESIS    " then valid = true end
+	if genesis_header["console_name"] == "SEGA MEGA DRIVE " then valid = true end
+	return valid
+end
+
 --Cart should be in reset state upon calling this function 
 --this function processes all user requests for this specific board/mapper
 local function process(process_opts, console_opts)
@@ -53,11 +187,14 @@ local function process(process_opts, console_opts)
     -- Initialize device i/o for SEGA
 	dict.io("IO_RESET")
 	dict.io("SEGA_INIT")
+	local genesis_header = read_header()
 
-
-	-- TODO: test cart by reading manf/prod ID
 	if process_opts["test"] then
-		unsupported("test")
+		-- If garbage data is in the header, it's a waste of time trying to proceed doing anything else.
+		local valid_header = test(genesis_header)
+		if valid_header ~= true then print("Unreadable cartridge - exiting! (Try cleaning cartridge connector?)") end
+		assert(valid_header)
+		print_header(genesis_header)
 	end
 
 	-- TODO: dump the ram to file 
@@ -67,16 +204,30 @@ local function process(process_opts, console_opts)
 
 	-- Dump the cart to dumpfile.
 	if process_opts["read"] then
+		
+		-- If ROM size wasn't provided, attempt to use value in internal header.
+		local rom_size = console_opts["rom_size_kbyte"]
+		if rom_size == 0 then
+			print("ROM Size not provided, " .. str_rom_size(genesis_header["rom_size"]) .. " detected.")
+			rom_size = genesis_header["rom_size"]
+		end
+
 		print("\nDumping SEGA ROM...")
-
 		file = assert(io.open(process_opts["dump_filename"], "wb"))
-
+		
 		--dump cart into file
-		dump_rom(file, console_opts["rom_size_kbyte"], false)
+		dump_rom(file, rom_size, false)
 
 		--close file
 		assert(file:close())
 		print("DONE Dumping SEGA ROM")
+		print("Computing checksum...")
+		local checksum = checksum_rom(process_opts["dump_filename"])
+		if checksum == genesis_header["checksum"] then
+			print("CHECKSUM OK! DUMP SUCCESS!")
+		else
+			print("CHECKSUM MISMATCH - BAD DUMP! (Try cleaning cartridge connector?)")
+		end
 	end
 
 	-- TODO: erase the cart

host/source/inlprog.c

@@ -330,7 +330,6 @@ int main(int argc, char *argv[])
 	}
 
 	if ((strcmp("gba", opts->console_name) == 0) ||
-	    (strcmp("genesis", opts->console_name) == 0) ||
 		(strcmp("n64", opts->console_name) == 0)) {
 		if (opts->rom_size_kbyte <= 0) {
 			printf("ROM size must be greater than 0 kilobytes.\n");