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   comp.lang.asm.x86      Ahh, the lost art of x86 assembly      4,675 messages   

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   Message 2,756 of 4,675   
   wolfgang kern to Kerr Mudd-John   
   Re: BASE64 again   
   29 Jun 17 09:12:13   
   
   From: nowhere@never.at   
      
    Kerr Mudd-John wrote:   
      
   >>> You inspired me to think of a horrible^w brilliant scheme, but this   
   >>> margin is too small to contain it.   
   >> Let me guess what you had in mind...   
   >> me too tried to get rid of the 2:1 at all and create the 4:3 decoder   
   >> with a 1:1 string and 'some' SMC modifications to fit into 041..07f.   
      
   > 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:   
      
   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]   
      
   my larger  59 byte: avoided 80..A7 (ROR/SHR mem,imm) 59+27+15+4=105   
   [59 +9p +5s +4]   
      
   another    59 byte: (ROR/SHR EDX) same modify needs as above.   
      
   my shorter 54 byte: (needs an 8x then) 54+33+15+4+2=108   
   [54 +11p +5s +4 +2]   
      
   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 :)   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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