From: nowhere@never.at   
      
   Kerr Mudd-John wrote:   
      
   >>> Yup; a whole heap of mods to the first line to make it a b64 decoder.   
      
   >> I may have reached the end of this story (or at least for now),   
   >> tried on:   
      
   > Darn! I was hoping for more inspiration! My attempt at a SMC 1st line   
   > B64 decoder is wallowing in fixup constant clashes.   
      
   I'm still here...even a bit lost in a dead end road.   
      
   First thing my variant does is to move the unmodified string to 044.   
      
   I need three bytes for one single or paired modify to produce 00..20   
   and A7..FF by one SUB, but it needs two bytes more to create 7B..A6.   
      
   ie:   
    PUSH 0x7761         ;could have used 0x7a61   
    POP AX              ;(4 byte)   
    SUB [bp+..],AL      ;21->C0 66->FB   
    SUB [bp+..],AH      ;21->AA   
    SUB [bp+..],AX      ;two at once   
    ...                 ;(+3 each)   
   but for 80..        ;(+2 more)   
    SUB AL,0x7a         ;ie: 5B -61-7a = 80   
    SUB [bp+..],AL      ;AX is possible too   
      
   >> your short 50 byte:(can't pair 83,86 with one 3byte sub) 50+33+18+4+2=107   
   >> [string +11 pairs +6 single +push imm16 pop ax +sub AL,7A]   
      
   > I'm using direct code for some ; e.g.   
   >   
   >           ; sub al,'a'-'A'-26   ; a-z ; sub al,6   
   >           sub al,0x5A   
   >           sub al,0x5A   
   >           sub al,0x52          ; whew! -6!   
      
   me too replaced a MOV CL,4 with four INC CX (was zero anyway) and   
   the larger variant used 8 bytes on two word XOR-clear instead of a   
   four byte 'AND dword [DI],0' (coz this need three bytes to modify).   
      
   would six DEC AX alter your AH ?   
      
   I had an ADD AL,06 in my code and replaced it with SUB AL,0xFA.   
   This FA is a 5B in the original but modified by SUB 61.   
   So only 2+3 bytes instead of 6.   
      
   I create FA (-6) with single sub by either "["-"a" or "q"-"w"   
      
   > as there's some room for expanding from 50 and 64; I dropped trying to   
   > keep it to pure B64.   
      
   Yeah, SMC with pure B64 seems impossible or at least heavy detouring.   
   ...   
   >> So when I look back to the xor-sub-sub 2:1 and your 50 byte variant   
   >> and compare what's required for direct modify with the 2:1 algo, we   
   >> may not gain too much :)   
      
   wasn't "shorter than this" our previous target ? :)   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
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