1 | IBM OS/400 implements iconv in an odd way:
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2 | - Type iconv_t is a structure: therefore objects of this type cannot be
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3 | compared to (iconv_t) -1.
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4 | - Supported character sets names are all of the form IBMCCSIDccsid..., where
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5 | ccsid is a decimal 5-digit integer identifying an IBM coded character set.
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6 | In addition, character set names have to be given in EBCDIC.
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7 | Standard character set names like "UTF-8" are NOT recognized.
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8 | - The prototype of iconv_open() does not declare parameters as const, although
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9 | they are not altered.
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10 |
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11 | Since libiconv does not support EBCDIC, use of this package here as a
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12 | replacement is not a solution.
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13 |
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14 | For these reasons, the code in this directory implements a wrapper to the
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15 | OS/400 iconv implementation. The wrapper performs the following transformations:
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16 | - Type iconv_t is an pointer. Although OS/400 pointers are odd, comparing
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17 | with (iconv_t) -1 is OK.
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18 | - All IANA character set names are recognized in a coding- and case-insensitive
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19 | way, providing an equivalent CCSID exists. see
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20 | http://www.iana.org/assignments/character-sets/character-sets.xhtml
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21 | - All CCSIDs from the association file can be expressed as IBMCCSIDxxxxx where
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22 | xxxxx is the 5 digit CCSID; no null terminator is required. Alternate codes
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23 | are of the form ibm-xxx (null-terminated), where xxx is the integer CCSID with
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24 | leading zeroes stripped.
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25 | - If a IANA BIBenum is defined for a CCSID, the name iana-xxx can be used,
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26 | where xxx is the integer MIBenum without leading zeroes.
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27 | - In addition, some aliases are also taken from the association file. Examples
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28 | are: ASCII, EBCDIC, UTF8.
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29 | - Prototype of iconv_open() has const parameters.
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30 | - Character code names can be given in any code.
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31 |
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32 | Character set names to CCSID conversion.
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33 | - http://www.iana.org/assignments/character-sets/character-sets.xhtml provides
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34 | all IANA registered character set names and aliases associated with a
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35 | MIBenum, that is a unique character set identifier.
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36 | - A hand-maintained file ccsid_mibenum.xml associates IBM CCSIDs to
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37 | IANA MBenums.
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38 | - An OS/400 C program (in subdirectory bldcsndfa) generates a deterministic
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39 | finite automaton from the files mentioned above into a C file for all
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40 | possible character set name and associating each of them with its
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41 | corresponding CCSID. This program can only be run on OS/400 since it uses
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42 | the native iconv support for EBCDIC.
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43 | - Since these operations are tedious and the table generation needs bootstraping
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44 | with libxml2, the generated automaton is stored within sources and need not
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45 | be rebuilt at each compilation. However, source is provided here to allow
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46 | new table generation with conversion tables that were not available at the
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47 | time of original generation.
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