SARC

2018-03-23T15:16:09Z

CuriousTommy: /* SARC Header */ Fixed byte-order

[[Category:File formats]]
=SARC File Format=
.sarc files are similar to the [[ARC]] format with a slightly different structure.

== File Format ==

=== SARC Header ===

{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x00
| 0x04
| Magic Bytes "SARC"
|-
| 0x04
| 0x02
| Header Length
|-
| 0x06
| 0x02
| Byte-order marker (0xFEFF = big, 0xFFFE = little)
|-
| 0x08
| 0x04
| File Length
|-
| 0x0C
| 0x04
| Data Offset (absolute)
|-
| 0x10
| 0x04
| Unknown (always 0x00000100)
|}

=== SFAT Header ===

{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x00
| 0x04
| Magic bytes "SFAT"
|-
| 0x04
| 0x02
| Header Length
|-
| 0x06
| 0x02
| Node Count
|-
| 0x08
| 0x04
| Filename Hash Multiplier (usually 0x65)
|}

=== SFAT Node ===

{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x00
| 0x04
| Name Hash
|-
| 0x04
| 0x04
| SFNT Filename Offset (relative to SFNT data section)
|-
| 0x08
| 0x04
| File Data Start (relative to SARC data start)
|-
| 0x0C
| 0x04
| File Data End (relative to SARC data end)
|}

==== Node hashing function ====

The node hash is calculated via:

Python:

def calc_hash(name, hash_multiplier):
result = 0

for c in name:
result = ord(c) + (result * hash_multiplier)
# ensure the result is a 32-bit value
result &= 0xFFFFFFFF

return result

C:

uint32_t calc_hash(char *name, int hash_multiplier) {
uint32_t result = 0;

for(int i = 0; i < strlen(name); i++) {
result = name[i] + (result * hash_multiplier)
}

return result;
}

=== SFNT Header ===

{| class="wikitable" border="1"
|-
! Offset
! Size
! Description
|-
| 0x00
| 0x04
| Magic bytes "SFNT"
|-
| 0x04
| 0x02
| Header Length
|-
| 0x06
| 0x02
| Unknown (padding?)
|}

=== SFNT Data ===

SFNT data immediately follows the SFNT header and consists of NULL-terminated ASCII strings.

=== File Data ===

File data begins after SFNT with 0x100 (256) byte alignment with all subsequent files aligned to 0x80 bytes.

== File Sort Order ==

Files are sorted by their hash in the SFAT table. Games seem to require this sorting as any other sort order prevents them from booting.

= Tools =

[https://github.com/ObsidianX/3dstools] - SARC Extractor/Creator with TAR-like command line flags. Can decompress a .zlib SARC file (4-byte size header + ZLIB data).

3dbrew - User contributions [en]

SARC