@blamnetwork/blf

Converting Reach Gametypes ​

Cross-build utilities live on a dedicated entry point (not the package root):

ts
import {
  convert_reach_gametype,
  e_reach_gametype_conversion_error,
} from "@blamnetwork/blf/helpers";
import { c_game_variant as tu1_variant } from "@blamnetwork/blf/haloreach/v12065_11_08_24_1738_tu1actual";
import { c_game_variant as mcc_variant } from "@blamnetwork/blf/haloreach_mcc/v_untracked_25_08_16_1352";

convert_reach_gametype(from, to) ​

Helper for converting game variants between Halo Reach on MCC and Xbox 360 (this library’s TU1 build). Pass two decoded c_game_variant instances from the matching version bundles; the function writes the result onto to.

The Master Chief Collection added megalo features that Xbox 360 builds do not have:

  • Temporary variables for objects, players, and teams
  • Additional math operators (<<=, >>=)
  • Eight MCC-only action types
  • “Network Test 1” firefight mode

See Megalo MCC changes for action names, payloads, and version bundle renames.

convert_reach_gametype(MCC, Xbox360) returns e_reach_gametype_conversion_error.ok on success. On failure it returns a specific error code — for example mcc_exclusive_action, mcc_exclusive_math_operator, mcc_survival_additional_flags, insufficient_global_slots, forge_variant, or campaign_variant. Forge and campaign gametypes are not yet supported.

Example (MCC → TU1) ​

Read an MCC mpvr from a buffer (find_chunk for a normal BLF; search_for_chunk for embedded data), convert the decoded gametype, then write a TU1 BLF:

ts
import { readFileSync, writeFileSync } from "node:fs";
import {
  convert_reach_gametype,
  e_reach_gametype_conversion_error,
} from "@blamnetwork/blf/helpers";
import { search_for_chunk, write_blffile } from "@blamnetwork/blf";
import { c_game_variant as tu1_variant } from "@blamnetwork/blf/haloreach/v12065_11_08_24_1738_tu1actual";
import {
  s_blf_chunk_end_of_file,
  s_blf_chunk_game_variant as tu1_mpvr,
  s_blf_chunk_start_of_file,
} from "@blamnetwork/blf/haloreach/v12065_11_08_24_1738_tu1actual";
import { s_blf_chunk_game_variant as mcc_mpvr } from "@blamnetwork/blf/haloreach_mcc/v_untracked_25_08_16_1352";

const buffer = new Uint8Array(readFileSync("mcc-variant.blf"));

const mccChunk = new mcc_mpvr();
if (!search_for_chunk(buffer, mccChunk, "big")) {
  throw new Error("mpvr chunk not found");
}

const from = mccChunk.game_variant;
const to = new tu1_variant();

if (convert_reach_gametype(from, to) !== e_reach_gametype_conversion_error.ok) {
  throw new Error("MCC gametype cannot be represented as TU1");
}

const tu1Blf = write_blffile("big", [
  s_blf_chunk_start_of_file.create("converted"),
  tu1_mpvr.create(to),
  new s_blf_chunk_end_of_file(),
]);

writeFileSync("tu1-variant.blf", tu1Blf);

After conversion, to holds the TU1 gametype; tu1_mpvr.create(to) encodes it for a TU1 mpvr chunk body.