@blamnetwork/blf

Writing chunks ​

BLF chunk headers are always written big-endian. Pass "big" or "little" to write / write_blffile for the chunk payload only (same rule as reading).

Single chunk ​

Each chunk class implements write(endian) (12-byte header + payload) and write_body(endian) (payload only):

ts
import { s_blf_chunk_author } from "@blamnetwork/blf/haloreach/v12065_11_08_24_1738_tu1actual";

const author = s_blf_chunk_author.forBuild({
  programName: "GameData.Reach",
  authorName: "blf_ts",
});

const bytes = author.write("big"); // full chunk including header

Use write_body when you are assembling payloads manually or testing layout without a BLF header.

write_blffile ​

Concatenate one or more chunks in order and return a single Uint8Array:

ts
import { write_blffile } from "@blamnetwork/blf";
import { s_blf_chunk_end_of_file } from "@blamnetwork/blf/halo3/v12070_08_09_05_2031_halo3_ship/s_blf_chunk_end_of_file";
import { s_blf_chunk_start_of_file } from "@blamnetwork/blf/halo3/v12070_08_09_05_2031_halo3_ship/s_blf_chunk_start_of_file";
import { s_blf_chunk_author } from "@blamnetwork/blf/haloreach/v12065_11_08_24_1738_tu1actual";

const blf = write_blffile("big", [
  s_blf_chunk_start_of_file.create("my-variant"),
  s_blf_chunk_author.forBuild({ programName: "GameData.Reach" }),
  chdr,
  mpvr,
  new s_blf_chunk_end_of_file(),
]);

Typical Reach gametype files include _blf, body chunks (chdr, mpvr, athr, …), then _eof. Import chunk classes from the version bundle that matches the target build.

_eof file_size ​

When the last chunk before _eof is written, write_blffile sets file_size on s_blf_chunk_end_of_file to the byte offset where _eof starts (the total size of all preceding chunks). You do not need to compute this yourself if _eof is the final entry in the array.

Errors ​

Layout and chunk failures throw BlfError.

See also: Reading chunks, Converting Reach gametypes for a full MCC → TU1 read/convert/write walkthrough.