c4lib is a C++ library for editing Civilization 4, Beyond the Sword (BTS) saves. c4lib is bundled with c4edit.
c4edit is a command line program built with c4lib that translates BTS saves into human-readable text. The format of the text file is similar to that of a debugger's memory view. The beginning of a "translation" is shown below.
Savegame: Tiny-Map-BC-4000.CivBeyondSwordSave
Schema: BTS.schema
Date: 01-12-2025 19:59:33.508379 UTC
c4lib version: 01.00.00
Offset Hex ASCII Translation
0x00000000 | -- -- -- -- | -- -- -- -- | -- -- -- -- | -- -- -- -- | ---------------- | Begin Savegame
0x00000000 | -- -- -- -- | -- -- -- -- | -- -- -- -- | -- -- -- -- | ---------------- | Begin GameHeader
0x00000000 | 2e 01 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | GameVersion=302
0x00000004 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | RequiredMod=""
0x00000008 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | ModMd5=""
0x0000000c | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | ChecksumDWord=0
0x00000010 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | LockModifiedAssetsText=""
0x00000014 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | LmaMd5_1=""
0x00000018 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | LmaMd5_2=""
0x0000001c | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | LmaMd5_3=""
0x00000020 | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | LmaMd5_4=""
0x00000024 | bf 05 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | CvInitCoreMd5Size=1471
0x00000028 | -- -- -- -- | -- -- -- -- | -- -- -- -- | -- -- -- -- | ---------------- | End GameHeader
0x00000028 | -- -- -- -- | -- -- -- -- | -- -- -- -- | -- -- -- -- | ---------------- | Begin CvInitCore
0x00000028 | 01 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | SaveFlag=1
0x0000002c | 00 00 00 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | ....------------ | Type=GAME_SP_NEW
0x00000030 | 10 00 00 00 | 50 00 61 00 | 73 00 73 00 | 65 00 6e 00 | ....P.a.s.s.e.n. | GameName="Passenger's Game"
0x00000040 | 67 00 65 00 | 72 00 27 00 | 73 00 20 00 | 47 00 61 00 | g.e.r.'.s. .G.a. | ...
0x00000050 | 6d 00 65 00 | -- -- -- -- | -- -- -- -- | -- -- -- -- | m.e.------------ | ...
c4edit has several uses.
For those simply curious about what a BTS save looks like, c4edit provides human-readable translations.
For more experienced users who want to make changes to a BTS save, c4edit can be used to generate info-format files for saves. The info files can be edited using a text editor, loaded back into c4edit, and then saved as a BTS save file (.CivBeyondSwordSave).
c4lib is a static C++ library that exposes a simple interface for loading saves and info files, and for generating saves, info files, and translations. The interface uses Boost Property Tree to store the representation of a BTS save. The Boost Property Tree API can be used to make changes to the property tree, which can then be saved in CivBeyondSwordSave format.
BTS saves store much of their data in zlib-compressed format. c4edit and c4lib understand this format, and are able to decompress the zlib-data making it available to view and edit.
Each BTS save ends with a checksum, used to ensure the integrity of the save. c4lib understands how the checksum is generated and updates the checksum whenever it saves a CivBeyondSwordSave- format file.
If you just want to use c4edit, download c4edit here, and follow the directions in QUICKSTART.md to configure c4edit for your computer.
If you're interested in C++ programming using the c4lib API, download c4edit and c4lib here. Then read QUICKSTART.md to configure c4edit, and API.md to learn about using c4lib.
If you're interested in downloading the sources, click here and then read BUILDING.md.
c4lib and c4edit are licensed under the MIT License. See LICENSE.
c4lib incorporates sources from copyrighted works as follows:
md5.hpp and md5.cpp: Copyright (c) 2014 Stephan Brumme. All rights reserved. See http://create.stephan-brumme.com/disclaimer.html for the license.
narrow.hpp: Copyright (c) 2015 Microsoft Corporation. All rights reserved. Licensed under the MIT License.