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Datasheet (view source)

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{{:Main_Page/Header}}
{{File format|name=Datasheet|version=1|magic=gsht|endianness=little}}
__NOTOC__ __NOEDITSECTION__
'''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'''.
{{:Main_Page/Getting_started}}
 
{{:Main_Page/Navigation}}
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.
== [[Main_Page/All_news|News]] ==
 
{{:Main_Page/News}}
== 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 ===
{| class="wikitable"
!Offset
!Type
!Description
|-
|0x0
|char[4]
|Magic (<code>gsht</code>)
 
After pointer relocation, the magic is set to <code>GSHT</code>.
|-
|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
|?{{Check}}
|-
|0x10
|const char*
|Name
|-
|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 <code>Field[num_root_fields]</code> array).
 
=== Field ===
<syntaxhighlight lang="c++">
enum class Type : u16 {
  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
};
</syntaxhighlight>
{| class="wikitable"
!Offset
!Type
!Description
|-
|0x0
|const char*
|Name (must be non-null)
|-
|0x8
|const char*
|Type name
|-
|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.
 
{| class="wikitable"
|+Field data serialization
!Type
!Serialized data format
|-
|Nullable<T> (non-strings)
|<code>struct { T* data; }</code> (nullptr if no value)
|-
|Array<T>
|<code>struct { T* data; u32 size; }</code> (aligned to 0x10 bytes{{Check}})
|-
|Struct
|<code>struct { Fields...; }</code>
|-
|Bool
|bool (1-byte)
|-
|Int
|s32
|-
|Float
|f32
|-
|String
|<code>struct { const char* data; u32 length; }</code> (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 [https://github.com/leoetlino/la-re-notes/tree/master/data/datasheets leoetlino/la-re-notes] repository on GitHub.
[[Category:File formats]]
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