79 lines
2.2 KiB
OCaml
79 lines
2.2 KiB
OCaml
open Unix
|
|
open Printf
|
|
|
|
(** http://bgb.bircd.org/pandocs.htm#thecartridgeheader *)
|
|
|
|
exception Read_error
|
|
|
|
type memory_bank_controller =
|
|
| ROM_ONLY
|
|
| MBC1
|
|
|
|
type t = {
|
|
nintendo_logo : bytes;
|
|
title : string;
|
|
(* mem_type : memory_bank_controller; *)
|
|
rom_size : int;
|
|
(* ram_size : int;
|
|
header_checksum : bytes;
|
|
global_checksum : bytes; *)
|
|
}
|
|
|
|
(** The Nintendo logo is a checksum in the header *)
|
|
let check_nintendo_logo cartridge =
|
|
let reference = Bytes.of_string
|
|
"\xCE\xED\x66\x66\xCC\x0D\x00\x0B\x03\x73\x00\x83\x00\x0C\x00\x0D\
|
|
\x00\x08\x11\x1F\x88\x89\x00\x0E\xDC\xCC\x6E\xE6\xDD\xDD\xD9\x99\
|
|
\xBB\xBB\x67\x63\x6E\x0E\xEC\xCC\xDD\xDC\x99\x9F\xBB\xB9\x33\x3E" in
|
|
(Bytes.compare cartridge.nintendo_logo reference) == 0
|
|
|
|
(** ROM size is expressed in KB *)
|
|
let get_ROM_size b =
|
|
match Bytes.get b 0 |> int_of_char with
|
|
| 0x00 -> 32 (* no ROM banking *)
|
|
| 0x01 -> 64 (* 4 banks *)
|
|
| 0x02 -> 128 (* 8 banks *)
|
|
| 0x03 -> 256 (* 16 banks *)
|
|
| 0x04 -> 512 (* 32 banks *)
|
|
| 0x05 -> 1000 (* 64 banks - only 63 banks used by MBC1 *)
|
|
| 0x06 -> 2000 (* 128 banks - only 125 banks used by MBC1 *)
|
|
| 0x07 -> 4000 (* 256 banks *)
|
|
| 0x52 -> 1100 (* 72 banks *)
|
|
| 0x53 -> 1200 (* 80 banks *)
|
|
| 0x54 -> 1500 (* 96 banks *)
|
|
| _ -> raise Read_error
|
|
|
|
|
|
let read_cartridge file =
|
|
try
|
|
let fd = openfile file [Unix.O_RDONLY] 0o644 in
|
|
|
|
try
|
|
let nin_logo_offset = 0x0104 in
|
|
if (lseek fd nin_logo_offset SEEK_SET) != nin_logo_offset
|
|
then raise Read_error;
|
|
|
|
let nin_logo_size = 48 in
|
|
let nintendo_logo = Bytes.create nin_logo_size in
|
|
if (read fd nintendo_logo 0 nin_logo_size) != nin_logo_size
|
|
then raise Read_error;
|
|
|
|
let title_size = 16 in
|
|
let title_b = Bytes.create title_size in
|
|
if (read fd title_b 0 title_size) != title_size
|
|
then raise Read_error;
|
|
let title = Bytes.to_string title_b in
|
|
|
|
let size_b = Bytes.create 1 in
|
|
let _ = lseek fd 4 SEEK_CUR in
|
|
if (read fd size_b 0 1) != 1
|
|
then raise Read_error;
|
|
let rom_size = get_ROM_size size_b in
|
|
|
|
Unix.close fd;
|
|
Some { nintendo_logo; title; rom_size }
|
|
|
|
with Read_error -> Unix.close fd; None
|
|
|
|
with Unix_error(err, cmd, msg) -> None
|