Re: How to scan an entire array all at once

From: Scott Klement <klemscot@xxxxxxxxxxxx>
Reply-To: RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
To: RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
Subject: Re: How to scan an entire array all at once
Date: Mon, 3 May 2004 17:03:42 -0500 (CDT)

Hi Marilyn,

[SNIP]
> The problem arises when the xml fragment I want to extract is spread between
> two array elements.
> Any ideas on an approach?

The memchr() and memcmp() functions from the ILE C runtime library can be
used to search an area of memory.  They have no idea what type of variable
they're scanning, etc, they just know that they're scanning memory.

You can use these functions in an ILE RPG program by providing the correct
prototypes.

The following is a subprocedure that I wrote for scanning memory.  (You
will have to bind your RPG program to the QC2LE binding directory.)

      *+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      *  ScanSpc():  Scan memory (or userspace) for a given string
      *
      *       Space = pointer to area of memory or user space to scan
      *      String = string to search for
      *     SpcSize = size of space to search
      *
      *  Returns 0 if nothing found, otherwise the position of the
      *             string in the space.
      *+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     P ScanSpc         B
     D ScanSpc         PI            10I 0
     D   Space                         *   value
     D   String                     256A   const varying options(*varsize)
     D   SpcSize                     10I 0 value

      * memchr(): Search memory for a character
     D memchr          PR              *   extproc('memchr')
     D   buf                           *   value
     D   chartofind                  10I 0 value
     D   bufsize                     10I 0 value

      * memcmp(): Compare two areas of memory
     D memcmp          PR            10I 0 extproc('memcmp')
     D   buf1                          *   value
     D   buf2                     65535A   const options(*varsize)
     D   size                        10I 0 value

     D                 DS
     D  Char                          1A
     D  Num                           3U 0 overlay(Char)

     D p_search        s               *
     D p_found         s               *

/free

           if (%len(String) < 1);
              return 0;
           endif;

Char = %subst(String: 1: 1);

p_search = Space;

           dou (memcmp(p_found: String: %len(String)) = 0);
               p_found = memchr(p_search: Num: SpcSize);
               if (p_found = *NULL);
                  return 0;
               endif;
               p_search = p_found + 1;
           enddo;

return (p_found - space) + 1;

      /end-free
     P                 E
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