From: nowhere@never.at   
      
   Kerr-Mudd,John wrote:   
      
   >>> For education and amusement I hereby present clax with a 5:4 (base85)   
   >>> decoder for DOS! Same caveat; the 1st 2 lines (well up to and   
   >>> including the eeeee string) must be "as is", reflowing (cr,lf spaces)   
   >>> should be OK afterwards.   
      
   > actually removing the crlf is OK, but not inserting newlines. I'd   
   > forgotten that whilst my ret slide of "dec bp" is usually OK it could be   
   > an issue here; but I reset bp to 0 in the secondary stage anyway.   
   > []   
   >> I'll check on it, but give me some more time ...   
      
   > Sure; it is a bit complicated (at least to me!). I use bp::dx as a qword   
   > accumulator for the 5:4 decoding.   
      
   I couldn't fully figure all details so far. What I got is your decoder at   
   03d..07e and it seem to work (I had to stop on the first INT21 call).   
   a few questions:   
      
   * DEC BP  JNO   you want a branch always?   
   OV is only set on transitions from 8000 to 7FFF (opposite for INC) but not   
   from 0 to FFFF and reverse, I dont think that my debugger is wrong.   
      
   * XOR BH,[si] JNZ 06A ;if this isn't a 'branch never' it may act endless.   
      
   * EXCH AL,AH  ;Big Endian encoded ?   
      
   perhaps you can save on one branch in the prologue: JB 0171 JA 0171   
   with a single JNE 0171.   
      
   Your encoder must be tricky to avoid some characters so your 5:4 format   
   can use 0x21..0x7D except quote marks (90 characters ?)   
      
   the use of 0x66 overrides may make the whole story easier ie:   
   ...   
   XOR eax,eax       ;or if bp=0 : push bp bp pop eax   
   LODSB             ;check/skip/end   
   ...   
   IMUL ebx,eax,0x55   
   ADD [di],ebx   
   ...               ;inner loop for powers 4,3,2,1   
   fifth:   
   ADD [di],eax   
   INC di   dup 4   
   ...               ;loop until end mark   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)