ASCII/EBCDIC Conversion

Chris,

I would typically refer you to APIs such as Convert a Graphic
Character String (QTQCVRT/CDRCVRT) or the iconv() family of conversion
APIs (all found in the System API Reference under National Language
Support APIs), but as you are asking for the "most efficient" I'll
suggest another approach which should be rather hard to beat if you
can live within a single byte (SBCS) environment.

There is an ILE MI instruction Translate Bytes (XLATEB) which you
could use directly from ILE RPG.  What you could do is create a field
containing the 256 bit patterns ranging from x'00' to x'ff' and then
call QDCXLATE, QTQCVRT, or CDRCVRT asking to have this field converted
from an appropriate EBCDIC CCSID such as 37 (or whatever EBCDIC CCSID
is appropriate as there are many) to an ASCII CCSID such as 819 (or
whatever ASCII code page/CCSID is appropriate as there are many).  The
returned buffer would then represent your EBCDIC to ASCII mapping table.
Then, using the same input field, call again QDCXLATE, QTQCVRT, etc.
specifying a from CCSID such as 819 and a to CCSID of 37.  This returned
buffer would then represent your ASCII to EBCDIC mapping table.  Then
just fall into direct calls to XLATEB using the appropriate EtoA or
AtoE table.  This approach does mean two calls to set up the mapping
tables; but no calls once you get into the actual string translations.

Bruce Vining

>
>Does anyone know the fasted and most efficient way to translate strings from
>ASCII to EBCDIC and back?  I am currently using CALL QDCXLATE and want to
>use the TABLES that IBM provides, QSYS/QASCII & QSYS/QEBCDIC.  Is there a
>way to load these tables into RPG tables at program init so I may use the
>XLATE opt code.  Would this use less CPU cycles?  Timing is critical in this
>application.
>
>Christopher K. Bipes
>

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