RE: int vs binary questions

[cozzi@xxxxxxxxx]

   Hans,
   That's all well and good, but...
   1) Why is DDS limited to 2 and 4 byte binaries and seems to use the
   RPG-like declaration for them (or has that changed?)
   2) Why would the timing of int->int copy be slower than Bin->Bin in RPG IV
   as was reported here earlier today?
    
   -Bob

    

     -------- Original Message --------
     Subject: Re: int vs binary questions
     From: "Hans Boldt" <boldt@xxxxxxxxxx>
     Date: Mon, February 09, 2004 12:23 pm
     To: rpg400-l@xxxxxxxxxxxx

     Steve Richter wrote:
     > I have a 170 with 460 cpw.  But that should not matter, all the
     results are
     > relative to the same system.  Bin to bin is 15% faster than int to
     int.  Add
     > to bin is off the charts, 20x slower than add to int.
     >
     > I would like to know if the rpg definition of "Binary" is unique to it
     and
     > if it predates the s/38.   And was the as400 database handling of
     binary
     > something forced on it by RPG?
     >

     Time again for a history lesson, eh?

     Let's go back to RPG II, as implemented on machines like the S/34. RPG
     II only had zoned decimal numeric as the internal representation for
     numerics. (Externally, it supported a bunch of other formats, like
     packed and binary decimal, left/right signed, etc.)

     RPG III on the S/38 added binary decimal and packed decimal as internal
     numeric formats, and made them work exactly the same as zoned decimal.
     (Call all three the "decimal" formats.) It did this by implicitly
     converting binary and zoned values to packed before all arithmetic.

     As far as DDS is concerned, "binary" can hold 2, 4, or 8 byte two's
     complement values. RPG is the odd one out since it maps DDS's "B" format
     into RPG's "B" format. Clearly, that's not always the best match, and
     never was.

     RPG IV added (eventually) three other numeric formats: float, integer,
     and unsigned, each with its own unique set of characteristics. As is
     true with most CPU's, the iSeries implements arithmetic fastest in
     binary, and so RPG's integer and unsigned formats are the fastest for
     arithmetic. For compatibility, RPG IV had to continue to map the "B"
     format in DDS to RPG's "B" format. Thus, the EXTBININT keyword is needed
     to tell the compiler to break compatibility, and do the right thing
     instead.

     Cheers! Hans

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