Re: asdbget - precision

["Jason M. Felice" <jasonf@xxxxxxxxxxxxxx>]

On Wed, Mar 15, 2000 at 05:20:28PM -0500, Sean Porterfield wrote:
> Toward the end of this function, what is the purpose of "v = -v;" ?
> It's what is causing my precision to show as negative on some fields in
> my XML (I haven't yet found a pattern or reason).  Before I just comment
> it out, I wanted to see if it had a purpose.  It may well be indicitive
> of a hidden bug somewhere, of a misunderstanding due to OS400 version
> differences.
> 
> (I'm on V4R2)
> 
> /* Convert a signed decimal field to a C `int' */
> static int
> signed2int (buf, len)
>         Byte *buf;
>         int len;
> {
>   int v = 0;
>   while (len)
>     {
>       v *= 10;
>       v += buf[0] & 0x0f;
>       len--;
>       buf++;
>     }
>   if ((buf[0] & 0xf0) == 0xd0)
>     v = -v;
>   return v;
> }

This converts an AS/400 signed field to an integer (we should probably be
converting to a long, but that doesn't matter on 32-bit architectures).  This
is IBM's zoned-decimal format, which stores one digit per byte and zone-shifts
the last digit if the field is negative.

Basically, ebcdic digits zero through nine are X'F0' - X'F9', but the last
digit is converted to X'D0' - X'D9' for a negative number.

However, looking over it for the fifth time, the function is in error.  Try
this instead:

/* Convert a signed decimal field to a C `int' */
static int
signed2int (buf, len)
        Byte *buf;
        int len;
{
  int v = 0;
  while (len)
    {
      v *= 10;
      v += buf[0] & 0x0f;
      len--;
      if (--len == 0 && (buf[0] & 0xf0) == 0xd0)
        v = -v;
      buf++;
    }
  return v;
}

It seems we were checking the zone of a random garbage character (the first
character after the end of the field).  I've just fixed this in CVS.

-Jay 'Eraserhead' Felice

> 
> 
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