Read RAM size.

src/cartridge.ml

@@ -14,8 +14,8 @@ type t = {
   title : string;
 (*  mem_type : memory_bank_controller; *)
   rom_size : int;
-(*  ram_size : int;
-  header_checksum : bytes;
+  ram_size : int;
+(*  header_checksum : bytes;
   global_checksum : bytes; *)
 }
 
@@ -43,6 +43,15 @@ let get_ROM_size b =
   | 0x54 -> 1500 (* 96 banks *)
   | _ -> raise Read_error
 
+(** RAM size is expressed in KB *)
+let get_RAM_size b =
+  match Bytes.get b 0 |> int_of_char with
+  | 0x00 -> 0
+  | 0x01 -> 2
+  | 0x02 -> 8
+  | 0x03 -> 32 (* 4 x 8KB banks *)
+  | _ -> raise Read_error
+
 
 let read_cartridge file =
   try
@@ -53,25 +62,33 @@ let read_cartridge file =
       if (lseek fd nin_logo_offset SEEK_SET) != nin_logo_offset
       then raise Read_error;
 
+      (* Nintendo logo *)
       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;
 
+      (* Title *)
       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
+      (* ROM size *)
+      let byte = Bytes.create 1 in
       let _ = lseek fd 4 SEEK_CUR in
-      if (read fd size_b 0 1) != 1
+      if (read fd byte 0 1) != 1
       then raise Read_error;
-      let rom_size = get_ROM_size size_b in
+      let rom_size = get_ROM_size byte in
+
+      (* RAM size *)
+      if (read fd byte 0 1) != 1
+      then raise Read_error;
+      let ram_size = get_RAM_size byte in
 
       Unix.close fd;
-      Some { nintendo_logo; title; rom_size }
+      Some { nintendo_logo; title; rom_size; ram_size }
 
     with Read_error -> Unix.close fd; None
 

src/oboy.ml

@@ -1,3 +1,4 @@
+open Cartridge
 open Printf
 
 (** Power up sequence
@@ -8,7 +9,8 @@ let power_up cartridge =
   then print_endline "Invalid ROM."
   else
     print_endline "Valid ROM.";
-    printf "ROM size: %iKB\n" cartridge.rom_size
+    printf "ROM size: %iKB\n" cartridge.rom_size;
+    printf "RAM size: %iKB\n" cartridge.ram_size
 
 
 let () =