ASM FASM base64 encode

[DDoSer]

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>format   PE GUI 4.0
 entry    start
 include  'win32a.inc'

 section  '.text' code executable readable

 start:

        lea        ebx,[base64log]
        lea        eax,[text]
        mov        [pszlog],eax
        invoke     lstrlen,[pszlog]
        stdcall    Base64Encode,dword [pszlog],ebx,eax
        invoke     MessageBoxA,0,base64log,0,0
        ret

;--------------------------------------------------
; [base64Encode]
;--------------------------------------------------

  proc Base64Encode lpSrc,lpDst,dwstrlen
          push       esi edi edx ebx

          mov        esi,[lpSrc]
          mov        edi,[lpDst]
          mov        ebx,dword [dwstrlen]
          call       b64.encode

          pop        ebx edx edi esi
          ret        
  endp    

; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; base64 encoder without dictionary by RT Fishel
; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  b64:       
    .newline:  
          call       b64.store_crlf

    .encode:   ; ebp = length, esi -> src buffer, edi -> dst buffer
          push       (76 shr 2) + 1
          pop        edx

    .outer:    
          dec        edx
          je         b64.newline
          lodsd      
          dec        esi
          inc        ebx
          bswap      eax
          mov        ecx,4

    .inner:    
          rol        eax,6
          and        al,3Fh
          cmp        al,3Eh
          jb         b64.testchar
          shl        al,2
          sub        al,((3Eh shl 2)+'A'-'+') and 0FFh

    .testchar: 
          sub        al,4
          cmp        al,'0'
          jnl        b64.store
          add        al,'A'+4
          cmp        al,'Z'
          jbe        b64.store
          add        al,'a'-'Z'-1

    .store:    
          stosb      
          dec        ebx
          loopne     b64.inner
          jne        b64.outer
          mov        al,'='
          rep        stosb
          xor        al,al
          stosb      
          ret        

    .store_crlf: 
          mov        ax,0a0dh
          stosw      

          ret        

 section  '.data' data writeable readable

          text                 db '1234',0
          pszlog               dd ?
          base64log            db 200 dup (?)

 section  '.idata' import data readable

 library  kernel32,'KERNEL32.DLL',\
          user32,  'USER32.DLL'

  include 'api/kernel32.inc'
  include 'api/user32.inc'

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