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

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   Message 2,787 of 4,675   
   wolfgang kern to Kerr Mudd-John   
   Re: Base64 follow-on   
   04 Jul 17 12:19:06   
   
   From: nowhere@never.at   
      
   Kerr Mudd-John wrote:   
   > Sorry Wolfgang I'm not sure if I've fixed my newsreader yet!   
      
   isn't a problem here.   
      
   > You spotted an error in my decoder of mov al,0x86; of course it should be:   
   >   
   >          mov al,0x45         ; fallthru   
   >          sbb al,0            ; '+'->62   
   >          ...   
      
   OK, copied and corrected:   
      
   1622:0105 2C 41   sub  al,41   
   1622:0107 73 0A   jnb  0113    ;040a(p)   
   1622:0109 04 45   add  al,45   
   1622:010B 3C 33   cmp  al,33   
   1622:010D 77 0A   ja   0119    ;B00a(p)   
   1622:010F B0 45   mov  al,45   
   1622:0111 1C 00   sbb  al,00   ;001c(p)   
   1622:0113 3C 1A   cmp  al,1A   ;(s)   
   1622:0115 72 02   jb   0119    ;(s)   
   1622:0117 2C 06   sub  al,06   ;(s)   
      
      
   so there are only six to modify yet.   
      
   Ok, we can start our own business and name it "Bug Exchange Service" :)   
      
   > I'm having difficulty with your decoder;   
      
   > I see this:   
   >   
   >                  sub al,0x47   
   >                  jnc havenum     ;0410 (p),06(s)   
   >                  add al,6        ;no gain with sub al,fa   
   >                  cmp al,0x1a     ;(s)   
   >                  jc  havenum     ;040a (p)   
   >                  add al,0x45   
   >                  cmp al,0x33     ; '/'   
   >                  ja  havenum     ;b004 (p)   
   >                  mov al,0x3f   
   >                  sbb al,0        ;(p)   
   > havenum:   
      
   > Am I missing some code? as G-Z don't get the right values.   
      
   Yeah it's wrong, seems I kept parts of my HEX-converter here.   
      
   > I like your simple ror and shr, luckily we're no longer decoding in place, or   
   > you'd zap the source.   
      
   I trade you my ROR/SHR against your GET-NUM :)   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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