The EX file format

EX files begin with a header with the following structure.

The compressed data is encrypted with a dictionary. It can be decrypted as follows,

uint8_t ex_decode_table[256];

void decode(uint8_t *compressed_data, size_t size)
{
    // initialize table
    for (int i = 0; i < 256; i++) {
        int tmpfor = i;
        int tmp = tmpfor;
        tmp = (tmp & 0x55) + ((tmp >> 1) & 0x55);
        tmp = (tmp & 0x33) + ((tmp >> 2) & 0x33);
        tmp = (tmp & 0x0F) + ((tmp >> 4) & 0x0F);
        if ((tmp & 0x01) == 0) {
            tmpfor = ((tmpfor << (8 - tmp)) | (tmpfor >> tmp)) & 0xFF;
        } else {
            tmpfor = ((tmpfor >> (8 - tmp)) | (tmpfor << tmp)) & 0xFF;
        }
        ex_decode_table[i] = tmpfor;
    }

    // decode data
    for (size_t i = 0; i < size; i++) {
        compressed_data[i] = ex_decode_table[i];
    }
}

Once the data is decrypted, it can be uncompressed using zlib.

Blocks

The uncompressed data is a list of blocks. Each block has a name, data type and associated data. The number of blocks in the list is given in the header described above.

EX Strings

Strings in EX files are encoded as pascal strings. Sometimes (not always!) they are zero-padded so that the length is a multiple of 4. I will refer to such padded strings as ‘ex-strings’ throughout this document.

Data Types

EX files can contain the following data types:

Tables

A table is a list of fields, followed by the table data.

Starting in Evenicle, the order of ‘Column count’ and ‘Row count’ is reversed.

Field Descriptors

If a field’s data type is EX_TABLE, then ‘Subfield count’ and ‘Subfields’ are present. ‘Subfields’ is a nested array of field descriptors.

Rows

A row is a list of cells. The number of cells contained in each row is given by the ‘Column count’ of the table, and the number of rows in a table is given by the ‘Row count’. A cell is a simple type-value pair:

Lists

List Items

Trees

Trees are encoded as a recursive node structure:

If ‘Is leaf?’ is 1, then ‘Node data’ contains a leaf node descriptor. If ‘Is leaf?’ is 0, then ‘Node data’ contains an intermediate node descriptor.

Leaf Nodes

Intermediate Nodes

Each entry in ‘Children’ is a full tree descriptor.