Function LoadChunk

src/saveload/oldloader.cpp:120–189

* * Loads a chunk from the old savegame * */

 *
 */
bool LoadChunk(LoadgameState &ls, void *base, const OldChunks *chunks)
{
	for (const OldChunks *chunk = chunks; chunk->type != OC_END; chunk++) {
		if (((chunk->type & OC_TTD) && _savegame_type == SGT_TTO) ||
				((chunk->type & OC_TTO) && _savegame_type != SGT_TTO)) {
			/* TTD(P)-only chunk, but TTO savegame || TTO-only chunk, but TTD/TTDP savegame */
			continue;
		}

		uint8_t *ptr = (uint8_t*)chunk->ptr;

		for (uint i = 0; i < chunk->amount; i++) {
			/* Handle simple types */
			if (GetOldChunkType(chunk->type) != 0) {
				switch (GetOldChunkType(chunk->type)) {
					/* Just read the byte and forget about it */
					case OC_NULL: ReadByte(ls); break;

					case OC_CHUNK:
						/* Call function, with 'i' as parameter to tell which item we
						 * are going to read */
						if (!chunk->proc(ls, i)) return false;
						break;

					case OC_ASSERT:
						Debug(oldloader, 4, "Assert point: 0x{:X} / 0x{:X}", ls.total_read, reinterpret_cast<size_t>(chunk->ptr) + _bump_assert_value);
						if (ls.total_read != reinterpret_cast<size_t>(chunk->ptr) + _bump_assert_value) throw std::exception();
					default: break;
				}
			} else {
				uint64_t res = 0;

				/* Reading from the file: bits 16 to 23 have the FILE type */
				switch (GetOldChunkFileType(chunk->type)) {
					case OC_FILE_I8:  res = (int8_t)ReadByte(ls); break;
					case OC_FILE_U8:  res = ReadByte(ls); break;
					case OC_FILE_I16: res = (int16_t)ReadUint16(ls); break;
					case OC_FILE_U16: res = ReadUint16(ls); break;
					case OC_FILE_I32: res = (int32_t)ReadUint32(ls); break;
					case OC_FILE_U32: res = ReadUint32(ls); break;
					default: NOT_REACHED();
				}

				/* When both pointers are nullptr, we are just skipping data */
				if (base == nullptr && chunk->ptr == nullptr) continue;

				/* Chunk refers to a struct member, get address in base. */
				if (chunk->ptr == nullptr) ptr = (uint8_t *)chunk->offset(base);

				/* Write the data */
				switch (GetOldChunkVarType(chunk->type)) {
					case OC_VAR_I8: *(int8_t  *)ptr = GB(res, 0, 8); break;
					case OC_VAR_U8: *(uint8_t *)ptr = GB(res, 0, 8); break;
					case OC_VAR_I16:*(int16_t *)ptr = GB(res, 0, 16); break;
					case OC_VAR_U16:*(uint16_t*)ptr = GB(res, 0, 16); break;
					case OC_VAR_I32:*(int32_t *)ptr = res; break;
					case OC_VAR_U32:*(uint32_t*)ptr = res; break;
					case OC_VAR_I64:*(int64_t *)ptr = res; break;