Datasheet

GSHT (G?sheet) is a custom Grezzo binary serialization file format that is used to store structured, strongly typed data. GSHT documents are called datasheets.

Datasheet

File format
Magic	gsht
Endianness	little
Version	1
This article is about the file format in general. For actual values, check the game RomFS.

A datasheet contains structure type information followed by arrays of structures. Optionally, one of the structure fields may be declared as a key field, in which case the contents are treated as a dictionary/mapping rather than a array.

Format

Documents are little endian and their sizes are always rounded up to be a multiple of 0x10.

Pointers are encoded as absolute offsets and relocated when the document is loaded by the game.

Header

Offset	Type	Description
0x0	char[4]	Magic (gsht) After pointer relocation, the magic is set to GSHT.
0x4	int	Version (must be 1)
0x8	u32	? Some kind of hash? (unused [check])
0xC	u8	Bool type size (must be 1)
0xD	u8	Pointer size (must be 8)
0xE	u8	Alignment (usually 4 or 8)
0x10	const char*	Name (must be non-null)
0x18	u32	Number of root fields
0x1C	u32	Number of fields in total
0x20	Value*	Values
0x28	u32	Number of values
0x2C	u32	Size of each value

The header is immediately followed by the root fields (a Field[num_root_fields] array).

Field

enum class Type : u8 {
  Struct = 0,
  Bool = 1,
  Int = 2,
  Float = 3,
  String = 4,
};

enum class Flag : u16 {
  IsNullable = 1 << 0,
  IsArray = 1 << 1,
  IsKey = 1 << 2,
  b3 = 1 << 3,  // unknown
  IsEnum = 1 << 4,
  b5 = 1 << 5,  // unknown
};

Offset	Type	Description
0x0	const char*	Name (must be non-null)
0x8	const char*	Type name (must be non-null)
0x10	Field::Type	Type
0x11	u8	?[check]
0x12	Field::Flag	Flags
0x14	u16	Offset of this field in the value structure
0x16	u16	Size of this field in the value structure For strings and arrays, this is always 0x10.
0x18	u16	Size of the data For strings and inline types (inline structs, ints, floats, bools), this is the same as the size in the value structure.
0x1A	u16	[For structs] Number of fields
0x20	Field*	[For structs] Fields
0x28	Field*	Parent (filled in during parsing; always 0xdeadbeefdeadbeef when serialized)

Fields must be properly aligned to 0x30 byte boundaries.

Key fields cannot be arrays or Nullable types.

Key fields must be of type String or Int.

Value

Combining all the root fields gives a structure (in the sense of a C or C++ structure). That structure is called a Value in this documentation.

Field data serialization

Type	Serialized data format
Nullable<T> (non-strings)	struct { T* data; } (nullptr if no value)
Array<T>	struct { T* data; u32 size; } (aligned to 0x10 bytes[check])
Struct	struct { Fields...; }
Bool	bool (1-byte)
Int	s32
Float	f32
String	struct { const char* data; u32 length; } (aligned to 0x10 bytes) For empty strings that are Nullable, data is nullptr and length is 0. Empty strings that are not Nullable have a 0 length but still point to a null byte.

Usage in Link's Awakening

Datasheets are extensively used to configure game logic and to store miscellaneous data. They are located in rom:/region_common/datasheets and their file extension is .gsheet.

Text versions of datasheets are available in the leoetlino/la-re-notes repository on GitHub.