Read Fallout 3 ESM files

Please note: This is a work in progress. It is only partially implemented and barely tested. Come back later.

This package parses the *.esm data files used by Fallout 3 and exposes the data as Objects via a Node.js Stream.

Another aim of this project is to provide documentation of the file format.

Usage

Add this as a dependency to your project:

npm install esm_reader --save

File structure and parsers

Values are stored in little endian format. This controls the Node Buffer methods to use.

Files always start with a TES4 record.

The rest of the file is divided into groups, described next.

parser/main.coffee.md switches to the appropriate parser based on the current state.

Groups

read_group_header.coffee.md parses the start of each group.

The rest of the group is made up of records, described next.

Records

read_record_header.coffee.md parses the start of each record.

The rest of the record is made up of fields, described next.

Fields

read_field.coffee.md parses field data from a Buffer.

A field contains a 4 byte label and then 2 bytes indicating the size of the field data. The remaining bytes store the value of the field.

Fields can contain different types of values: text, numbers, bit flags, or lists of those. The type of the value are not described by the field, but rather determined by the labels of the group+record+field.