RE: Base64 Encoding

Beppe,

I've been looking over your code below and I have a understand everything 
except where you are using 255 in the %bitand function.  I don't see where it 
has any effect on the result.  Am I missing something?

Rick

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Beppe Costagliola
Sent: Wednesday, November 10, 2004 3:22 AM
To: RPG programming on the AS400 / iSeries
Subject: Re: Base64 Encoding


This is what I'm using to decode mail attachements:

d QUSPTRUS        PR                  extpgm('QUSPTRUS')
d  UserSpace                    20    const
d  UserSpacePtr                   *

D Input           S              4A   based(i_attachement)
D Output          S              3A   based(o_attachement)

D attachement     DS                  based(p_attachement)
D  attachName                   64
D  attachSize                   10
D  attachFiller                 22

D s_attachement   S             10I 0

D tbBase64        S             65A

D w               S             10I 0 dim(4)
D Char            ds
D ww                             3U 0
D wa                             1A   overlay(ww)

D iPos            S             10I 0
D oPos            S             10I 0

D MimeDecode      PR            10I 0
D  Input                         1A   const

 /free

  // initialize the table
  tbBase64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
             'abcdefghijklmnopqrstuvwxyz' +
             '0123456789+/=';

  // get workspaces
  QUSPTRUS ('BASE64    QTEMP     ' : i_attachement);
  QUSPTRUS ('ATTACHMENTQTEMP     ' : p_attachement);
 // set the output pointer past the header (name+size)
 o_attachement = p_attachement + %size(attachement);

 // decode
 dow Input <> *loval;

   iPos = 1;
   oPos = 1;
   w(1) = MimeDecode(%subst(Input: iPos: 1));
   w(2) = MimeDecode(%subst(Input: iPos + 1: 1));
   w(3) = MimeDecode(%subst(Input: iPos + 2: 1));
   w(4) = MimeDecode(%subst(Input: iPos + 3: 1));

   ww = %bitand ((w(1) * 4 + %Int(w(2) / 16)):255);
   %subst(Output: oPos: 1) = wa;

   ww = %bitand ((w(2) * 16 + %Int(w(3) / 4)):255);
   %subst(Output: oPos + 1: 1)  = wa;

   ww = %bitand ((w(3) * 64 + w(4)):255);
    %subst(Output: oPos + 2: 1)  = wa;

    i_attachement += 4;
    o_attachement += 3;

  enddo;

  // set the final attachement size into workspace
  s_attachement = o_attachement - p_attachement - %size(attachement);
  attachSize = %trim(%editc(s_attachement:'Z'));

  *inlr = *on;

 /end-free

P MimeDecode      B
D MimeDecode      PI            10I 0
D  Input                         1A   const
 /free

  return %scan(Input: tbBase64) - 1;
 /end-free
P MimeDecode      E