Format for StarDict dictionary files ------------------------------------ StarDict homepage: http://stardict.sourceforge.net {0}. Number and Byte-order Conventions When you record the numbers that identify sizes, offsets, etc., you should use 32-bit numbers, such as you might represent with a glong. In order to make StarDict work on different platforms, these numbers must be in network byte order. You can ensure the correct byte order by using the g_htonl() function when creating dictionary files. Conversely, you should use g_ntohl() when reading dictionary files. Strings should be encoded in UTF-8. {1}. Files Every dictionary consists of three files: (1). somedict.ifo (2). somedict.idx or somedict.idx.gz (3). somedict.dict or somedict.dict.dz You can use gzip -9 to compress the .idx file. If the .idx file are not compressed, the loading can be fast and save memory when using, compress it will make the .idx file load into memory and make the quering fast when using. You can use dictzip to compress the .dict file. "dictzip" uses the same compression algorithm and file format as does gzip, but provides a table that can be used to randomly access compressed blocks in the file. The use of 50-64kB blocks for compression typically degrades compression by less than 10%, while maintaining acceptable random access capabilities for all data in the file. As an added benefit, files compressed with dictzip can be decompressed with gunzip. For more information about dictzip, refer to DICT project, please see: http://www.dict.org Stardict will search for the .ifo file, then open the .idx or .idx.gz file and the .dict.dz or .dict file which is in the same directory and has the same base name. {2}. The ".ifo" file's format. The .ifo file has the following format: StarDict's dict ifo file version=2.4.2 [options] Note that the current "version" string must be "2.4.2". If it's not, then StarDict will refuse to read the file. [options] --------- In the example above, [options] expands to any of the following lines specifying information about the dictionary. Each option is a keyword followed by an equal sign, then the value of that option, then a newline. The options may be appear in any order. Note that the dictionary must have at least a bookname, a wordcount and a idxfilesize, or the load will fail. All other information is optional. All strings should be encoded in UTF-8. Available options: bookname= // required wordcount= // required idxfilesize= // required author= email= website= description= date= sametypesequence= // very important. wordcount is the count of word entries in .idx file, it must be right. idxfilesize is the size(in bytes) of the .idx file, even the .idx is compressed to a .idx.gz file, this entry must record the original .idx file's size, and it must be right too. The .gz file don't contain its original size information, but knowing the original size can speed up the extraction to memory, as you don't need to call realloc() for many times. The "sametypesequence" option is described in further detail below. *** sametypesequence You should first familiarize yourself with the .dict file format described in the next section so that you can understand what effect this option has on the .dict file. If the sametypesequence option is set, it tells StarDict that each word's data in the .dict file will have the same sequence of datatypes. In this case, we expect a .dict file that's been optimized in two ways: the type identifiers should be omitted, and the size marker for the last data entry of each word should be omitted. Let's consider some concrete examples of the sametypesequence option. Suppose that a dictionary records many .wav files, and so sets: sametypesequence=W In this case, each word's entry in the .dict file consists solely of a wav file. In the .dict file, you would leave out the 'W' character before each entry, and you would also omit the 32-bit integer at the front of each .wav entry that would normally give the entry's length. You can do this since the length is known from the information in the idx file. As another example, suppose a dictionary contains phonetic information and a meaning for each word. The sametypesequence option for this dictionary would be: sametypesequence=tm Once again, you can omit the 't' and 'm' characters before each data entry in the .dict file. In addition, you should omit the terminating '\0' for the 'm' entry for each word in the .dict file, as the length of the meaning string can be inferred from the length of the phonetic string (still indicated by a terminating '\0') and the length of the entire word entry (listed in the .idx file). So for cases where the last data entry for each word normally requires a terminating '\0' character, you should omit this character in the dict file. And for cases where the last data entry for each word normally requires an initial 32-bit number giving the length of the field (such as WAV and PNG entries), you must omit this number in the dictionary. Every dictionary should try to use the sametypesequence feature to save disk space. *** {3}. The ".idx" file's format. The .idx file is just a word list. The word list is a sorted list of word entries. Each entry in the word list contains three fields, one after the other: word_str; // a utf-8 string terminated by '\0'. word_data_offset; // word data's offset in .dict file word_data_size; // word data's total size in .dict file word_str gives the string representing this word. It's the string that is "looked up" by the StarDict. word_data_offset and word_data_size should both be 32-bit numbers in network byte order. No two entries should have the same "word_str". In other words, (strcmp(s1, s2) != 0). The length of "word_str" should be less than 256. In other words, (strlen(word) < 256). The word list must be sorted by calling stardict_strcmp() on the "word_str" fields. If the word list order is wrong, StarDict will fail to function correctly! ============ gint stardict_strcmp(const gchar *s1, const gchar *s2) { gint a; a = g_ascii_strcasecmp(s1, s2); if (a == 0) return strcmp(s1, s2); else return a; } ============ g_ascii_strcasecmp() is a glib function: Unlike the BSD strcasecmp() function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII characters as if they are not letters. stardict_strcmp() works fine with English characters, but the other locale characters' sorting is not so good. There should be a _strcmp function which handles the utf-8 string sorting better. If you know one, email me :) g_utf8_collate()? This is a locale-dependent funcition. So if you look up Chinese characters while in the Chinese locale, it works fine. But if you are in some other locale then the lookup will fail, as the order is not the same as in the Chinese locale (which was used when creating the dictionary). g_utf8_to_ucs4() then do comparing? This sounds like a good solution, but.. The complete solution can be found in "Unicode Technical Standard #10: Unicode Collation Algorithm", http://www.unicode.org/reports/tr10/ I hope glib will provide a locale-independent g_utf8_collate() soon. http://bugzilla.gnome.org/show_bug.cgi?id=112798 {4}. The ".dict" file's format. The .dict file is a pure data sequence, as the offset and size of each word is recorded in the corresponding .idx file. If the "sametypesequence" option is not used in the .ifo file, then the .dict file has fields in the following order: ============== word_1_data_1_type; // a single char identifying the data type word_1_data_1_data; // the data word_1_data_2_type; word_1_data_2_data; ...... // the number of data entries for each word is determined by // word_data_size in .idx file word_2_data_1_type; word_2_data_1_data; ...... ============== It's important to note that each field in each word indicates its own length, as described below. The number of possible fields per word is also not fixed, and is determined by simply reading data until you've read word_data_size bytes for that word. Suppose the "sametypesequence" option is used in the .idx file, and the option is set like this: sametypesequence=tm Then the .dict file will look like this: ============== word_1_data_1_data word_1_data_2_data word_2_data_1_data word_2_data_2_data ...... ============== The first data entry for each word will have a terminating '\0', but the second entry will not have a terminating '\0'. The omissions of the type chars and of the last field's size information are the optimizations required by the "sametypesequence" option described above. Type identifiers ---------------- Here are the single-character type identifiers that may be used with the "sametypesequence" option in the .idx file, or may appear in the dict file itself if the "sametypesequence" option is not used. Lower-case characters signify that a field's size is determined by a terminating '\0', while upper-case characters indicate that the data begins with a 32-bit integer that gives the length of the data field. 'm' Word's pure text meaning. The data should be a utf-8 string ending with '\0'. 'l' Word's pure text meaning. The data is NOT a utf-8 string, but is instead a string in locale encoding, ending with '\0'. Sometimes using this type will save disk space, but its use is discouraged. 'g' A utf-8 string which is marked up with the Pango text markup language. For more information about this markup language, See the "Pango Reference Manual." You might have it installed locally at: file:///usr/share/gtk-doc/html/pango/PangoMarkupFormat.html 't' English phonetic string. The data should be a utf-8 string ending with '\0'. Here are some utf-8 phonetic characters: θʃŋʧðʒæıʌʊɒɛəɑɜɔˌˈːˑ æɑɒʌәєŋvθðʃʒːɡˏˊˋ 'y' Chinese YinBiao. The data should be a utf-8 string ending with '\0'. 'W' wav file. The data begins with a network byte-ordered glong to identify the wav file's size, immediately followed by the file's content. 'P' png file. The data begins with a network byte-ordered glong to identify the png file's size, immediately followed by the file's content. 'X' this type identifier is reserved for experimental extensions. {5}. Tree Dictionary The tree dictionary support is used for information viewing, etc. A tree dictionary contains three file: sometreedict.ifo, sometreedict.tdx.gz and sometreedict.dict.dz. It is better to compress the .tdx file, as it is always load into memory. The .ifo file has the following format: StarDict's treedict ifo file version=2.4.2 [options] Available options: bookname= // required tdxfilesize= // required wordcount= author= email= website= description= date= sametypesequence= wordcount is only used for info view in the dict manage dialog, so it is not important in tree dictionary. The .tdx file is just the word list. ----------- The word list is a tree list of word entries. Each entry in the word list contains four fields, one after the other: word_str; // a utf-8 string terminated by '\0'. word_data_offset; // word data's offset in .dict file word_data_size; // word data's total size in .dict file. it can be 0. word_subentry_count; //have many sub word this entry has, 0 means none. Subentry is immidiately followed by its parent entry. This make the order is just as when a tree list with all its nodes extended, then sort from top to bottom. The .dict file's format is the same as the normal dictionary. {6}. More information. You can read "src/lib.cpp", "src/dictmanagedlg.cpp" and "src/tools/*.cpp" for more information. If you have any questions, email me. :) Thanks to Will Robinson for cleaning up this file's English. Hu Zheng http://forlinux.yeah.net 2003.11.11