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ICONV - Charset Conversion Library. Version 2.0
-----------------------------------------------
This distribution provides:
* the library (libiconv.a and .so) for conversion between
various charsets (character encoding schemes);
* and the command line utility (iconv), providing
conversion of a file, standard input or its argument
line from one charset to another;
* a set of coded character set tables (binary files) and
character encoding schemes (dynamically loaded modules)
for use by the library;
* a utility for creating character set tables from Unicode
conversion tables and RFC1345-style charset descriptions.
Syntax of the library functions (iconv_open, iconv, iconv_close)
and the utility is described in the man pages.
Features of the library:
- Coded character set (CCS) tables are binary files containing
pairs of tables for converting characters from some charset to
Unicode (UCS-2 in host byte order) and vice versa. There are 4
types of tables supported in iconv-2.0: for 7-bit, 8-bit, 14-bit
and 16-bit charsets. The library uses memory mapping (in
read-only mode) to access the table data.
- Character encoding schemes (CES) are small sets of C structures
and functions. The functions implement virtual methods for
converting a sequence of characters in some charset to a Unicode
character (UCS-4 in host byte order). Each encoding scheme is
located in a separate C file and can be compiled to a dynamically
loaded shared module.
- A universal CES for all table driven charsets is compiled into
the library and used for all CCS tables.
- Both CCS tables and CES C code can be built into the library by
specifying the corresponding charset name in the
ICONV_BUILTIN_CHARSETS make variable. By default us-ascii, utf-8
and ucs-4-internal are built in (plus the CES for all CCS
tables). All the CES modules are included to a static version of
the library (libiconv.a).
- Multiple aliases for every charset are supported. All aliases are
listed in the charset.aliases file(s). The library uses memory
mapping to parse alias information and find a canonical name
of a charset before looking it up in the internal list or
external table or shared module. Alias information can also be
compiled into the library (which is useful for compiled-in
charsets ;-)
- ISO/IEC 10646 conformance of the internal representation of
characters; conversion is done in two steps:
(1) a sequence of zero or more bytes from input buffer coded in
the source charset is converted to exactly one valid UCS-4
character and
(2) the UCS-4 character is converted to a sequence of zero or
more bytes in the target charset to the output buffer.
In the case when two charset names are found to be aliases
of the same charset, conversion is done via a simplified
converter by copying the data from the input buffer to the
output one.
- Open module API: adding new modules is easy. API has only been
documented via iconv.h file comments so far. A perl utility is
provided for conversion of Unicode charset tables
(http://www.unicode.org/Public/MAPPINGS/) and RFC1345-style
charset tables into the CCS format recognized by the library.
- API conformance to Unix98 specification.
- BSD-style copyright.
Konstantin Chuguev
<Konstantin.Chuguev@dante.org.uk>
November 2000.
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