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

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   Message 2,788 of 4,675   
   wolfgang kern to Kerr Mudd-John   
   Re: Base64 follow-on   
   05 Jul 17 10:49:11   
   
   From: nowhere@never.at   
      
   Kerr Mudd-John wrote:   
      
   >> Seems I can post but not read!   
   > (sometimes)   
      
   I can repeat what you may have missed.   
      
   >> Your "search for dh" method looks useful!   
      
   yes, but after we added MOV CL at start DH needs to be changed   
   to 53:   
   044 53 7c              ;"S|"   
   and I changed the second constant SUB al,7a to SUB al,41 for it.   
      
   044 B1 04        mov cl,04       ;7c53-77a2=04b1(p-41)   
   046 55 55        push bp  dup2   
   048 66 8f 05     pop dword [DI]  ;clr four, 058f(p-41)   
      
   04b AC           lodsb           ;(s ah)   
   04c 3c 2b        cmp al,2b   
   04e 72 fb        jc 04b          ;(s)   
   050 3c 3d        cmp al,3d   
   052 75 01        jnz 055         ;   
   054 C3           ret             ;c301 (p)   
   I took your 'working' 20 byte GetNum yet   
   055 2c 41        sub al,41   
   057 73 0a        jnc 063         ;040a (p),   
   059 04 45        add al,45       ;   
   05b 3c 33        cmp al,33       ;   
   05d 77 0a        ja 069          ;b00a (p)   
   05f b0 45        mov al,45   
   061 1c 00        sbb al,0        ;001c (p)   
   063 3c 1a        cmp al 1a       ;(s)   
   065 72 02        jc 069          ;(s)   
   067 2c 06        sub al,06       ;(s)   
      
   069 08 05        or [di],al      ;0508 (p)   
   06b 66 c1 05 46  ROR dword [di],6;05c1 (p) tricky 46   
   06f e2 da        loop 04b        ;dae2 (p)   
   071 66 c1 2d 48  SHR dword [di],8;(s) tricky 48   
   075 47 47 47     inc di dup 3   
   078 eb ca        jmp 044         ;caeb (p)   
   07a ***   
      
   all [bp+..] offsets and some mod-values need to be adjusted now...   
   just a manual side-play during the next coffee break.   
   But we are down to 54 byte and only 16 modifiers. This fits well   
   and make me think about these three unused bytes now :)   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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