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This document is about the format of CTR cart images (CCI), which is also the format of 3DS ROM dumps.
See also: [[NCSD]].
 
This page documents the format of NCSD. CTR cart images (CCI) is NCSD, but is used for other things as well. CSU is NCSD used for system updates and development tools.
 
This is a container format which generally holds [[CXI]] files inside.


=== Overview ===
=== Overview ===
CCI files start with a NCSD header which is 4096 bytes long, followed by 4 [[CXI]] blocks. While it is unknown what each CXI block is for, the second one is most likely the main program code since it is much bigger than the others.
NCSD images start with a NCSD header, followed by up to a maximum of 8 partitions according to spec. The first partition(NCCH 0) usually starts at 0x4000, this is generally the main NCCH executable. The following info on partitions 1, 2, and 7 are only valid for .CCI. The second partition(NCCH 1) contains the game "Manual"(title ID for the .CXI containing the Manual always starts with '0005'). The third partition(NCCH 2) contains the download play "Child"(The title ID for the NCCH containing the Child always starts with '0006'). The eighth block(NCCH 7) contains "Update Data"(The title ID for the NCCH containing the Update Data always starts with '8000') The format of partitions can be determined from the partition FS flags, while the contents can be determined from the partitions flags.
 
The first CXI block always begins at 0x1000, and appears to lack a RSA-2048 signature. The offsets to the other blocks are found inside the NCSD header.


=== NCSD header ===
=== NCSD header ===
{| class="wikitable" border="1"
{| class="wikitable" border="1"
|-
|-
!  OFFSET
!  Offset
!  SIZE
!  Size
!  DESCRIPTION
!  Description
|-
|-
|  0x000
|  0x000
|  0x100
|  0x100
|  RSA-2048 signature of the NCSD header, using SHA-256 (needs to be confirmed)
|  RSA-2048 SHA-256 signature of the NCSD header
|-
|-
|  0x100
|  0x100
|  4
|  4
|  Magic ID, always 'NCSD'
|  Magic Number 'NCSD'
|-
|-
|  0x104
|  0x104
|  4
|  4
|  Size of the CCI image, in media units (1 media unit = 0x200 bytes)
|  Size of the NCSD image, in media units (1 media unit = 0x200 bytes)
|-
|-
|  0x108
|  0x108
|  8
|  8
|  Title ID(?)
|  Title/Program ID
|-
|-
|  0x120
|  0x110
|  4
|  8
|  Offset to the second CXI in media units
|  Partitions FS type
|-
|-
|  0x124
|  0x118
|  4
|  8
|  Size of the second CXI
|  Partitions crypt type
|-
|-
|  0x130
|  0x120
|  4
|  0x40=(4+4)*8
|  Offset to the third CXI
|  Offset & Length partition table
|-
|-
|  0x134
|  0x160
|  4
|  0x20
|  Size of the third CXI
|  Exheader SHA-256 hash
|-
|-
|  0x158
|  0x180
|  4
|  0x4
|  Offset to the fourth CXI
|  Additional header size
|-
|-
|  0x15C
|  0x184
|  4
|  0x4
|  Size of the fourth CXI
|  Sector zero offset
|-
|-
|  0x18C
|  0x188
|  4
|  8
|  Unknown (always 0x00000101)
|  Partition Flags: byte[5]-byte[7] indicate content type ( system update, application, manual, ... ) size of media units ( 512*2^byte[6] ) and encryption.
|-
|-
|  0x190
|  0x190
|  8
|  0x40=8*8
|  Partition ID of the second CXI
|  Partitions' Title ID table
|-
|-
|  0x1A0
|  0x1D0
|  8
|  0x28
|  Partition ID of the third CXI
|  Reserved
|-
|-
|  0x1C8
|  0x1F8
|  8
|  8
|  Partition ID of the fourth CXI
|  Unknown
|-
|-
|  0x200
|  0x200
|  4
|  4
|  Always 0xFFFFFFFF
|  Always 0xFFFFFFFF
|-
|  0x204
|  252
|  Padding?
|-
|-
|  0x300
|  0x300
|  4
|  4
|  Used ROM size in bytes
|  Used ROM size in bytes
|-
|  0x304
|  28
|  Padding
|-
|-
|  0x320
|  0x320
|  16
|  8
|  Unknown
|  [[NVer]] Title ID (Only Present in retail .CCI)
|-
|  0x328
|  8
|  [[NVer]] Title Version (Only Present in retail .CCI)
|}
|}


CCI images may not include all four CXI blocks. For example, Ghost Recon: Shadow Wars lacks the third CXI. Entries at 0x130, 0x134 and 0x1A0 in its NCSD header are zero.
Parts of the first NCCH block's header are found around 0x1000 for whatever reason. NCSD can hold up to 8 partitions. (i.e. Mario Kart 7 holds 4 NCCHs, most we've seen so far)
 
The region-specific NVer title for this NCSD presumably must exist on NAND. The NVer title version may also be used to check whether a system update is required before running the app.
 
[[Category:File formats]]
Retrieved from "https://www.3dbrew.org/wiki/CCI"