forked from enlightenment/efl
more of eet docs in .h - all of it minus examples actually.
SVN revision: 58475
This commit is contained in:
parent
296739cd7d
commit
b504157045
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@ -1,257 +0,0 @@
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/**
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@file eet.dox
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@brief Eet Data Handling Library Public API Calls
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These routines are used for Eet Library interaction
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*/
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/**
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@mainpage Eet Library Documentation
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@image html e_big.png
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@version @PACKAGE_VERSION@
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@author Carsten Haitzler <raster@@rasterman.com>
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@author David Goodlad <dgoodlad@@gmail.com>
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@author Cedric Bail <cedric.bail@@free.fr>
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@author Arnaud de Turckheim <quarium@@gmail.com>
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@author Luis Felipe Strano Moraes <lfelipe@@profusion.mobi>
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@author Chidambar Zinnoury <illogict@@online.fr>
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@author Vincent Torri <vtorri@@univ-evry.fr>
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@author Gustavo Sverzut Barbieri <barbieri@@profusion.mobi>
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@author Raphael Kubo da Costa <kubo@@profusion.mobi>
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@author Mathieu Taillefumier <mathieu.taillefumier@@free.fr>
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@author Albin "Lutin" Tonnerre <albin.tonnerre@@gmail.com>
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@author Adam Simpkins <adam@@adamsimpkins.net>
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@date 2000-2011
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@section toc Table of Contents
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@li @ref intro
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@li @ref example
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@li @ref format
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@li @ref compiling
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@li @ref install
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@li @ref next_steps
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@li @ref intro_example
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@section intro What is Eet?
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It is a tiny library designed to write an arbitrary set of chunks of data
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to a file and optionally compress each chunk (very much like a zip file)
|
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and allow fast random-access reading of the file later on. It does not
|
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do zip as a zip itself has more complexity than is needed, and it was much
|
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simpler to implement this once here.
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Eet is extremely fast, small and simple. Eet files can be very small and
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highly compressed, making them very optimal for just sending across the
|
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internet without having to archive, compress or decompress and install them.
|
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They allow for lightning-fast random-acess reads once created, making them
|
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perfect for storing data that is written once (or rarely) and read many
|
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times, but the program does not want to have to read it all in at once.
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It also can encode and decode data structures in memory, as well as image
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data for saving to Eet files or sending across the network to other
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machines, or just writing to arbitrary files on the system. All data is
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encoded in a platform independent way and can be written and read by any
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architecture.
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@section example A simple example on using Eet
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Here is a simple example on how to use Eet to save a series of strings to a
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file and load them again. The advantage of using Eet over just fprintf() and
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fscanf() is that not only can these entries be strings, they need no special
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parsing to handle delimiter characters or escaping, they can be binary data,
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image data, data structures containing integers, strings, other data
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structures, linked lists and much more, without the programmer having to
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worry about parsing, and best of all, Eet is very fast.
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@code
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#include <Eet.h>
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int
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main(int argc, char **argv)
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{
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Eet_File *ef;
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int i;
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char buf[32];
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char *ret;
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int size;
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char *entries[] =
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{
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"Entry 1",
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"Big text string here compared to others",
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"Eet is cool"
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};
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eet_init();
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// blindly open an file for output and write strings with their NUL char
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ef = eet_open("test.eet", EET_FILE_MODE_WRITE);
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eet_write(ef, "Entry 1", entries[0], strlen(entries[0]) + 1, 0);
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eet_write(ef, "Entry 2", entries[1], strlen(entries[1]) + 1, 1);
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eet_write(ef, "Entry 3", entries[2], strlen(entries[2]) + 1, 0);
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eet_close(ef);
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// open the file again and blindly get the entries we wrote
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ef = eet_open("test.eet", EET_FILE_MODE_READ);
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ret = eet_read(ef, "Entry 1", &size);
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printf("%s\n", ret);
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ret = eet_read(ef, "Entry 2", &size);
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printf("%s\n", ret);
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ret = eet_read(ef, "Entry 3", &size);
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printf("%s\n", ret);
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eet_close(ef);
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eet_shutdown();
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}
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@endcode
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@section format What does an Eet file look like?
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The file format is very simple. There is a directory block at the start of
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the file listing entries and offsets into the file where they are stored,
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their sizes, compression flags etc. followed by all the entry data strung one
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element after the other.
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All Eet files start with t a 4 byte magic number. It is written using network
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byte-order (big endian, or from most significant byte first to least
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significant byte last) and is 0x1ee7ff00 (or byte by byte 0:1e 1:e7 2:ff
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3:00). The next 4 bytes are an integer (in big endian notation) indicating
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how many entries are stored in the Eet file. 0 indicates it is empty. This is
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a signed integer and thus values less than 0 are invalid, limiting the number
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of entries in an Eet file to 0x7fffffff entries at most. The next 4 bytes is
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the size of the directory table, in bytes, encoded in big-endian format. This
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is a signed integer and cannot be less than 0.
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The directory table for the file follows immediately, with a continuous list
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of all entries in the Eet file, their offset in the file etc. The order of
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these entries is not important, but convention would have them be from first
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to last entry in the file. Each directory entry consiste of 5 integers, one
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after the other, each stored as a signed, big endian integer. The first is
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the offset in the file that the data for this entry is stored at (based from
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the very start of the file, not relative to the end of the directory block).
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The second integer holds flags for the entry. currently only the least
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significant bit (bit 0) holds any useful information, and it is set to 1 if
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the entry is compressed using zlib compression calls, or 0 if it is not
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compressed. The next integer is the size of the entry in bytes stored in the
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file. The next integer is the size of the data when decompressed (if it was
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compressed) in bytes. This may be the same as the previous integer if the
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entry was not compressed. The final integer is the number of bytes used by
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the string identifier for the entry, without the NUL byte terminator, which
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is not stored. The next series of bytes is the string name of the entry, with
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the number of bytes being the same as specified in the last integer above.
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This list of entries continues until there are no more entries left to list.
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To read an entry from an Eet file, simply find the appropriate entry in the
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directory table, find it's offset and size, and read it into memory. If it is
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compressed, decompress it using zlib and then use that data.
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Here is a data map of an Eet file. All integers are encoded using big-endian
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notation (most significant byte first) and are signed. There is no alignment
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of data, so all data types follow immediately on, one after the other. All
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compressed data is compressed using the zlib compress2() function, and
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decompressed using the zlib uncompress() function. Please see zlib
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documentation for more information as to the encoding of compressed data.
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@verbatim
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HEADER:
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[INT] Magic number (0x1ee7ff00)
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[INT] Number of entries in the directory table
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[INT] The size of the directory table, in bytes
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DIRECTORY TABLE ENTRIES (as many as specified in the header):
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[INT] Offest from file start at which entry is stored (in bytes)
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[INT] Entry flags (1 = compressed, 0 = not compressed)
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[INT] Size of data chunk in file (in bytes)
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[INT] Size of the data chunk once decompressed (or the same as above, if not)
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[INT] The length of the string itendifier, in bytes, without NUL terminator
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[STR] Series of bytes for the string identifier, no NUL terminator
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... more directory entries
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DATA STORED, ONE AFTER ANOTHER:
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[DAT] DATA ENTRY 1...
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[DAT] DATA ENTRY 2...
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[DAT] DATA ENTRY 3...
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... more data chunks
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@endverbatim
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The contents of each entry in an Eet file has no defined format as such. It
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is an opaque chunk of data, that is up to the application to deocde, unless
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it is an image, ecoded by Eet, or a data structure encoded by Eet. The data
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itself for these entries can be encoded and decoded by Eet with extra helper
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functions in Eet. eet_data_image_read() and eet_data_image_write() are used
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to handle reading and writing image data from a known Eet file entry name.
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eet_data_read() and eet_data_write() are used to decode and encode program
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data structures from an Eet file, making the loading and saving of program
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information stored in data structures a simple 1 function call process.
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Please see src/lib/eet_data.c for information on the format of these
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specially encoded data entries in an Eet file (for now).
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@section compiling How to compile using Eet ?
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Eet is a library your application links to. The procedure for this is very
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simple. You simply have to compile your application with the appropriate
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compiler flags that the @p pkg-config script outputs. For example:
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Compiling C or C++ files into object files:
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@verbatim
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gcc -c -o main.o main.c `pkg-config --cflags eet`
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@endverbatim
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Linking object files into a binary executable:
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@verbatim
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gcc -o my_application main.o `pkg-config --libs eet`
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@endverbatim
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You simply have to make sure that pkg-config is in your shell's PATH (see
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the manual page for your appropriate shell) and eet.pc in /usr/lib/pkgconfig
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or its path is in the PKG_CONFIG_PATH environment variable. It's that simple
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to link and use Eet once you have written your code to use it.
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Since the program is linked to Eet, it is now able to use any advertised
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API calls to serialize your data.
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You should make sure you add any extra compile and link flags to your
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compile commands that your application may need as well. The above example
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is only guaranteed to make Eet add it's own requirements.
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@section install How is it installed?
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Simple:
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@verbatim
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./configure
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make
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su -
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...
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make install
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@endverbatim
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@section next_steps Next Steps
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After you understood what Eet is and installed it in your system you
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should proceed understanding the programming interface. We'd recommend
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you to take a while to learn Eina
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(http://docs.enlightenment.org/auto/eina/) as it is very convenient
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and optimized, and Eet provides integration with it.
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Recommended reading:
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@li @ref Eet_File_Group to know the basics to open and save files.
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@li @ref Eet_Data_Group to know the convenient way to serialize and
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parse your data structures automatically. Just create your
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descriptors and let Eet do the work for you.
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@section intro_example Introductory Examples
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@ref Examples
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@todo Document data format for images and data structures.
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*/
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@ -1,3 +1,257 @@
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/**
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@brief Eet Data Handling Library Public API Calls
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These routines are used for Eet Library interaction
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@mainpage Eet Library Documentation
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@image html e_big.png
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@version 1.0.0
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@author Carsten Haitzler <raster@@rasterman.com>
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@author David Goodlad <dgoodlad@@gmail.com>
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@author Cedric Bail <cedric.bail@@free.fr>
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@author Arnaud de Turckheim <quarium@@gmail.com>
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@author Luis Felipe Strano Moraes <lfelipe@@profusion.mobi>
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@author Chidambar Zinnoury <illogict@@online.fr>
|
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@author Vincent Torri <vtorri@@univ-evry.fr>
|
||||
@author Gustavo Sverzut Barbieri <barbieri@@profusion.mobi>
|
||||
@author Raphael Kubo da Costa <kubo@@profusion.mobi>
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||||
@author Mathieu Taillefumier <mathieu.taillefumier@@free.fr>
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@author Albin "Lutin" Tonnerre <albin.tonnerre@@gmail.com>
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@author Adam Simpkins <adam@@adamsimpkins.net>
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@date 2000-2011
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||||
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@section toc Table of Contents
|
||||
|
||||
@li @ref intro
|
||||
@li @ref example
|
||||
@li @ref format
|
||||
@li @ref compiling
|
||||
@li @ref install
|
||||
@li @ref next_steps
|
||||
@li @ref intro_example
|
||||
|
||||
@section intro What is Eet?
|
||||
|
||||
It is a tiny library designed to write an arbitrary set of chunks of data
|
||||
to a file and optionally compress each chunk (very much like a zip file)
|
||||
and allow fast random-access reading of the file later on. It does not
|
||||
do zip as a zip itself has more complexity than is needed, and it was much
|
||||
simpler to implement this once here.
|
||||
|
||||
Eet is extremely fast, small and simple. Eet files can be very small and
|
||||
highly compressed, making them very optimal for just sending across the
|
||||
internet without having to archive, compress or decompress and install them.
|
||||
They allow for lightning-fast random-acess reads once created, making them
|
||||
perfect for storing data that is written once (or rarely) and read many
|
||||
times, but the program does not want to have to read it all in at once.
|
||||
|
||||
It also can encode and decode data structures in memory, as well as image
|
||||
data for saving to Eet files or sending across the network to other
|
||||
machines, or just writing to arbitrary files on the system. All data is
|
||||
encoded in a platform independent way and can be written and read by any
|
||||
architecture.
|
||||
|
||||
@section example A simple example on using Eet
|
||||
|
||||
Here is a simple example on how to use Eet to save a series of strings to a
|
||||
file and load them again. The advantage of using Eet over just fprintf() and
|
||||
fscanf() is that not only can these entries be strings, they need no special
|
||||
parsing to handle delimiter characters or escaping, they can be binary data,
|
||||
image data, data structures containing integers, strings, other data
|
||||
structures, linked lists and much more, without the programmer having to
|
||||
worry about parsing, and best of all, Eet is very fast.
|
||||
|
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@code
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#include <Eet.h>
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int
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main(int argc, char **argv)
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{
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Eet_File *ef;
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int i;
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char buf[32];
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char *ret;
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int size;
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char *entries[] =
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{
|
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"Entry 1",
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"Big text string here compared to others",
|
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"Eet is cool"
|
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};
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eet_init();
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// blindly open an file for output and write strings with their NUL char
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ef = eet_open("test.eet", EET_FILE_MODE_WRITE);
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eet_write(ef, "Entry 1", entries[0], strlen(entries[0]) + 1, 0);
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eet_write(ef, "Entry 2", entries[1], strlen(entries[1]) + 1, 1);
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eet_write(ef, "Entry 3", entries[2], strlen(entries[2]) + 1, 0);
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eet_close(ef);
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// open the file again and blindly get the entries we wrote
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ef = eet_open("test.eet", EET_FILE_MODE_READ);
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ret = eet_read(ef, "Entry 1", &size);
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printf("%s\n", ret);
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ret = eet_read(ef, "Entry 2", &size);
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printf("%s\n", ret);
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ret = eet_read(ef, "Entry 3", &size);
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printf("%s\n", ret);
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eet_close(ef);
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eet_shutdown();
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}
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@endcode
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|
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@section format What does an Eet file look like?
|
||||
|
||||
The file format is very simple. There is a directory block at the start of
|
||||
the file listing entries and offsets into the file where they are stored,
|
||||
their sizes, compression flags etc. followed by all the entry data strung one
|
||||
element after the other.
|
||||
|
||||
All Eet files start with t a 4 byte magic number. It is written using network
|
||||
byte-order (big endian, or from most significant byte first to least
|
||||
significant byte last) and is 0x1ee7ff00 (or byte by byte 0:1e 1:e7 2:ff
|
||||
3:00). The next 4 bytes are an integer (in big endian notation) indicating
|
||||
how many entries are stored in the Eet file. 0 indicates it is empty. This is
|
||||
a signed integer and thus values less than 0 are invalid, limiting the number
|
||||
of entries in an Eet file to 0x7fffffff entries at most. The next 4 bytes is
|
||||
the size of the directory table, in bytes, encoded in big-endian format. This
|
||||
is a signed integer and cannot be less than 0.
|
||||
|
||||
The directory table for the file follows immediately, with a continuous list
|
||||
of all entries in the Eet file, their offset in the file etc. The order of
|
||||
these entries is not important, but convention would have them be from first
|
||||
to last entry in the file. Each directory entry consiste of 5 integers, one
|
||||
after the other, each stored as a signed, big endian integer. The first is
|
||||
the offset in the file that the data for this entry is stored at (based from
|
||||
the very start of the file, not relative to the end of the directory block).
|
||||
The second integer holds flags for the entry. currently only the least
|
||||
significant bit (bit 0) holds any useful information, and it is set to 1 if
|
||||
the entry is compressed using zlib compression calls, or 0 if it is not
|
||||
compressed. The next integer is the size of the entry in bytes stored in the
|
||||
file. The next integer is the size of the data when decompressed (if it was
|
||||
compressed) in bytes. This may be the same as the previous integer if the
|
||||
entry was not compressed. The final integer is the number of bytes used by
|
||||
the string identifier for the entry, without the NUL byte terminator, which
|
||||
is not stored. The next series of bytes is the string name of the entry, with
|
||||
the number of bytes being the same as specified in the last integer above.
|
||||
This list of entries continues until there are no more entries left to list.
|
||||
To read an entry from an Eet file, simply find the appropriate entry in the
|
||||
directory table, find it's offset and size, and read it into memory. If it is
|
||||
compressed, decompress it using zlib and then use that data.
|
||||
|
||||
Here is a data map of an Eet file. All integers are encoded using big-endian
|
||||
notation (most significant byte first) and are signed. There is no alignment
|
||||
of data, so all data types follow immediately on, one after the other. All
|
||||
compressed data is compressed using the zlib compress2() function, and
|
||||
decompressed using the zlib uncompress() function. Please see zlib
|
||||
documentation for more information as to the encoding of compressed data.
|
||||
|
||||
@verbatim
|
||||
HEADER:
|
||||
[INT] Magic number (0x1ee7ff00)
|
||||
[INT] Number of entries in the directory table
|
||||
[INT] The size of the directory table, in bytes
|
||||
|
||||
DIRECTORY TABLE ENTRIES (as many as specified in the header):
|
||||
[INT] Offest from file start at which entry is stored (in bytes)
|
||||
[INT] Entry flags (1 = compressed, 0 = not compressed)
|
||||
[INT] Size of data chunk in file (in bytes)
|
||||
[INT] Size of the data chunk once decompressed (or the same as above, if not)
|
||||
[INT] The length of the string itendifier, in bytes, without NUL terminator
|
||||
[STR] Series of bytes for the string identifier, no NUL terminator
|
||||
... more directory entries
|
||||
|
||||
DATA STORED, ONE AFTER ANOTHER:
|
||||
[DAT] DATA ENTRY 1...
|
||||
[DAT] DATA ENTRY 2...
|
||||
[DAT] DATA ENTRY 3...
|
||||
... more data chunks
|
||||
@endverbatim
|
||||
|
||||
The contents of each entry in an Eet file has no defined format as such. It
|
||||
is an opaque chunk of data, that is up to the application to deocde, unless
|
||||
it is an image, ecoded by Eet, or a data structure encoded by Eet. The data
|
||||
itself for these entries can be encoded and decoded by Eet with extra helper
|
||||
functions in Eet. eet_data_image_read() and eet_data_image_write() are used
|
||||
to handle reading and writing image data from a known Eet file entry name.
|
||||
eet_data_read() and eet_data_write() are used to decode and encode program
|
||||
data structures from an Eet file, making the loading and saving of program
|
||||
information stored in data structures a simple 1 function call process.
|
||||
|
||||
Please see src/lib/eet_data.c for information on the format of these
|
||||
specially encoded data entries in an Eet file (for now).
|
||||
|
||||
|
||||
@section compiling How to compile using Eet ?
|
||||
|
||||
Eet is a library your application links to. The procedure for this is very
|
||||
simple. You simply have to compile your application with the appropriate
|
||||
compiler flags that the @p pkg-config script outputs. For example:
|
||||
|
||||
Compiling C or C++ files into object files:
|
||||
|
||||
@verbatim
|
||||
gcc -c -o main.o main.c `pkg-config --cflags eet`
|
||||
@endverbatim
|
||||
|
||||
Linking object files into a binary executable:
|
||||
|
||||
@verbatim
|
||||
gcc -o my_application main.o `pkg-config --libs eet`
|
||||
@endverbatim
|
||||
|
||||
You simply have to make sure that pkg-config is in your shell's PATH (see
|
||||
the manual page for your appropriate shell) and eet.pc in /usr/lib/pkgconfig
|
||||
or its path is in the PKG_CONFIG_PATH environment variable. It's that simple
|
||||
to link and use Eet once you have written your code to use it.
|
||||
|
||||
Since the program is linked to Eet, it is now able to use any advertised
|
||||
API calls to serialize your data.
|
||||
|
||||
You should make sure you add any extra compile and link flags to your
|
||||
compile commands that your application may need as well. The above example
|
||||
is only guaranteed to make Eet add it's own requirements.
|
||||
|
||||
|
||||
@section install How is it installed?
|
||||
|
||||
Simple:
|
||||
|
||||
@verbatim
|
||||
./configure
|
||||
make
|
||||
su -
|
||||
...
|
||||
make install
|
||||
@endverbatim
|
||||
|
||||
@section next_steps Next Steps
|
||||
|
||||
After you understood what Eet is and installed it in your system you
|
||||
should proceed understanding the programming interface. We'd recommend
|
||||
you to take a while to learn Eina
|
||||
(http://docs.enlightenment.org/auto/eina/) as it is very convenient
|
||||
and optimized, and Eet provides integration with it.
|
||||
|
||||
Recommended reading:
|
||||
|
||||
@li @ref Eet_File_Group to know the basics to open and save files.
|
||||
@li @ref Eet_Data_Group to know the convenient way to serialize and
|
||||
parse your data structures automatically. Just create your
|
||||
descriptors and let Eet do the work for you.
|
||||
|
||||
@section intro_example Introductory Examples
|
||||
|
||||
@ref Examples
|
||||
|
||||
@todo Document data format for images and data structures.
|
||||
|
||||
*/
|
||||
|
||||
#ifndef _EET_H
|
||||
#define _EET_H
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue