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