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IBM OS/400 implements iconv in an odd way:
- Type iconv_t is a structure: therefore objects of this type cannot be
compared to (iconv_t) -1.
- Supported character sets names are all of the form IBMCCSIDccsid..., where
ccsid is a decimal 5-digit integer identifying an IBM coded character set.
In addition, character set names have to be given in EBCDIC.
Standard character set names like "UTF-8" are NOT recognized.
- The prototype of iconv_open() does not declare parameters as const, although
they are not altered.
Since libiconv does not support EBCDIC, use of this package here as a
replacement is not a solution.
For these reasons, the code in this directory implements a wrapper to the
OS/400 iconv implementation. The wrapper performs the following transformations:
- Type iconv_t is an pointer. Although OS/400 pointers are odd, comparing
with (iconv_t) -1 is OK.
- All IANA character set names are recognized in a coding- and case-insensitive
way, providing an equivalent CCSID exists. see
http://www.iana.org/assignments/character-sets/character-sets.xhtml
- All CCSIDs from the association file can be expressed as IBMCCSIDxxxxx where
xxxxx is the 5 digit CCSID; no null terminator is required. Alternate codes
are of the form ibm-xxx (null-terminated), where xxx is the integer CCSID with
leading zeroes stripped.
- If a IANA BIBenum is defined for a CCSID, the name iana-xxx can be used,
where xxx is the integer MIBenum without leading zeroes.
- In addition, some aliases are also taken from the association file. Examples
are: ASCII, EBCDIC, UTF8.
- Prototype of iconv_open() has const parameters.
- Character code names can be given in any code.
Character set names to CCSID conversion.
- http://www.iana.org/assignments/character-sets/character-sets.xhtml provides
all IANA registered character set names and aliases associated with a
MIBenum, that is a unique character set identifier.
- A hand-maintained file ccsid_mibenum.xml associates IBM CCSIDs to
IANA MBenums.
- An OS/400 C program (in subdirectory bldcsndfa) generates a deterministic
finite automaton from the files mentioned above into a C file for all
possible character set name and associating each of them with its
corresponding CCSID. This program can only be run on OS/400 since it uses
the native iconv support for EBCDIC.
- Since these operations are tedious and the table generation needs bootstraping
with libxml2, the generated automaton is stored within sources and need not
be rebuilt at each compilation. However, source is provided here to allow
new table generation with conversion tables that were not available at the
time of original generation.
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