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Archive Extension Format

States how Reloaded3 Package Extends the NX Archive Format via User Data

Data Types

  • String8 is assumed to be a 1 byte length prefixed UTF-8 string.
  • Align4 pads the data to the next 4 byte boundary.
  • Align8 pads the data to the next 8 byte boundary.

If the offset is already aligned, no padding is added. The byte 00 is recommended for padding.

Header (Standard)

The user data format for standard packages has an Extension ID of R3PK

This is 0x5233504B in big endian. For Reloaded3PacKage.

Header (Delta Update)

The user data format for standard packages has an Extension ID of R3DT

This is 0x52334454 in big endian. For Reloaded3DelTa.

The header is the following:

Patch Info

Immediately follows the header.

First part lists the number of items which follow:

NumPatchTargets is calculated by summing all values of PatchTargetCounts.

The PatchTargetPaths are the paths of all files.

An example

NumPatches: 3
PatchTargetCounts: [2, 1, 3]
PatchTargetPaths: [
    "textures/armor.dds",
    "textures/armor_normal.dds",
    "scripts/main.lua",
    "models/character.nif",
    "models/weapon.nif",
    "models/shield.nif"
]

  1. The output of PatchSources[0] + PatchFileIndices[0] produces 2 files:

    • "textures/armor.dds"
    • "textures/armor_normal.dds"

  2. The output of PatchSources[1] + PatchFileIndices[1] produces 1 file:

    • "scripts/main.lua"

  3. The output of PatchSources[2] + PatchFileIndices[2] produces 3 files:

    • "models/character.nif"
    • "models/weapon.nif"
    • "models/shield.nif"

PatchFileIndices

These are the 0 based indexes of the patch files as they appear in the NX archive.

This is an array of u32 values.

A value of 0 means the first file in the archive's file entries.

PatchSources

These are the hashes of the source files

The PatchSources and PatchFileIndices form tuples.

So PatchSources[0] has the hash of the file from the previous version of the package that you should apply the patch at PatchFileIndices[0] to.

To find the original file, we check the original mod folder and find the file with the corresponding XXH3 hash using the File Hash Cache.

PatchTargetCounts

Each PatchSources and PatchFileIndices tuple can output multiple files.

When there are duplicate files in the new version of the package, we can reuse a pre-generated patch for them. In this case, the PatchTargetCounts will be greater than 1; as this is the number of files that the source+patch output will output to.

PatchTargetPaths

These are the relative paths of the files that the PatchSources and PatchFileIndices tuples will output to.

Extract Info

Immediately follows Patch Info

This is a list of files to extract from the NX archive to output directory raw.

The files are extracted to paths that are the same as in the archive.

  • Align4
  • u32: NumFilesToExtract
  • u32[NumFilesToExtract]: FilesToExtract

This is the list of files that's not in previous version but is in new version.

Copy Info

Immediately follows Extract Info

This is a list of files that need to be copied (verbatim) from the previous version of the package to the new version.

  • Align4
  • u32: NumFilesToCopy
  • XXH3[NumFilesToCopy]: FilesToCopy
  • String8[NumFilesToCopy]: RelativeOutputPaths

Discovering Deltas

Deltas can be discovered by using the Central Server's Download Information API.

To determine if you can apply the patch, use the Delta Verification API.