asm
    push ebx
    push esi
    push edi

    mov esi, [SourcePtr]
    mov edi, [Target]
    {$IFDEF GIF_SAFE}
    xor ebx, ebx
    {$ELSE}
    mov ebx, [StackPointer]
    {$ENDIF}
    mov ch, byte ptr [Bits]
    mov cl, byte ptr [CodeSize]

  @@loop:
    {$IFDEF GIF_SAFE}
    cmp   [Bad], 0
    jnz   @@exit
    {$ENDIF}

    mov eax, [UnpackedSize]
    test eax, eax
    setle al
    mov edx, [PackedSize]
    test edx, edx
    setle ah
    or   al, ah
    jnz  @@exit

    {$IFDEF GIF_LOG}
    pushad
    mov eax, [UnpackedSize]
    mov edx, [PackedSize]
    mov ecx, [Data]
    call doGifLog
    popad
    {$ENDIF}

    movzx eax, byte ptr [esi]
    xchg  cl, ch
    shl   eax, cl
    xchg  cl, ch
    add   [Data], eax
    add   ch, 8

  @@while:
    {$IFDEF GIF_SAFE}
    cmp   [Bad], 0
    jnz   @@exit
    {$ENDIF}

    cmp   ch, cl
    jb    @@e_while

    mov   eax, [Data]
    and   eax, [CodeMask]
    shr   [Data], cl

    sub   ch, cl
    cmp   eax, [EOICode]
    jz    @@e_while

  @@1:
    cmp   eax, [ClearCode]
    jnz   @@2

    mov   cl, [initial_code_size]
    inc   cl
    xor   eax, eax
    inc   eax
    shl   eax, cl
    dec   eax
    mov   [CodeMask], eax
    mov   eax, [ClearCode]
    add   eax, 2
    mov   [FreeCode], eax
    mov   [OldCode], NoLZWCode
    jmp   @@while

  @@2:
    cmp   eax, [FreeCode]
    ja    @@e_while

  @@3:
    cmp   [OldCode], NoLZWCode
    jne   @@4

    mov   [OldCode], eax
    {$IFDEF GIF_SAFE}
    cmp   eax, GIFBufSize-1
    jle   @@suffix_good1
    mov   [Bad], 1
    and   eax, GIFBufSize-1
  @@suffix_good1:
    {$ENDIF}
    mov   al, byte ptr [suffix+eax]
    mov   [FirstChar], al
    {$IFDEF GIF_LOG}
    pushad
    call  doGifLog2
    popad
    {$ENDIF}
    stosb
    dec   [UnpackedSize]
    jmp   @@while

  @@4:
    mov   [InCode], eax
    cmp   eax, [FreeCode]
    jne   @@5

    mov   al, [FirstChar]
    {$IFDEF GIF_SAFE}
    cmp   ebx, GIFBufSize
    jae   @@stk_bad1
    mov   byte ptr [Stack+ebx], al
    inc   ebx
    jmp   @@stk_good1
  @@stk_bad1:
    mov   [Bad], 1
  @@stk_good1:
    {$ELSE}
    mov   [ebx], al
    inc   ebx
    {$ENDIF}
    mov   eax, [OldCode]

  @@5:
    cmp   eax, [ClearCode]
    jbe   @@6

    {$IFDEF GIF_SAFE}
    cmp   eax, GIFBufSize-1
    jle   @@suffix_good2
    and   eax, GIFBufSize-1
    mov   [Bad], 1
  @@suffix_good2:
    {$ENDIF}
    mov   dl, byte ptr [Suffix+eax]
    {$IFDEF GIF_SAFE}
    cmp   ebx, GIFBufSize
    jb    @@stk_good2
    mov   [Bad], 1
    jmp   @@exit
  @@stk_good2:
    mov   byte ptr [Stack+ebx], dl
    inc   ebx
  @@stk_bad2:
    cmp   eax, GIFBufSize-1
    jle   @@Prefix_good1
    and   eax, GIFBufSize-1
    mov   [Bad], 1
  @@Prefix_good1:
    {$ELSE}
    mov   byte ptr [ebx], dl
    inc   ebx
    {$ENDIF}
    mov   eax, dword ptr [Prefix+eax*4]
    jmp   @@5

  @@6:
    {$IFDEF GIF_SAFE}
    cmp   eax, GIFBufSize-1
    jle   @@suffix_good3
    and   eax, GIFBufSize-1
    mov   [Bad], 1
  @@suffix_good3:
    {$ENDIF}
    mov   dl, byte ptr [Suffix+eax]
    mov   [FirstChar], dl
    {$IFDEF GIF_SAFE}
    cmp   ebx, GIFBufSize
    jae   @@stk_bad3
    mov   byte ptr [Stack+ebx], dl
    inc   ebx
    jmp   @@stk_good3
  @@stk_bad3:
    mov   [Bad], 1
  @@stk_good3:
    {$ELSE}
    mov   byte ptr [ebx], dl
    inc   ebx
    {$ENDIF}

    mov   eax, [FreeCode]
    {$IFDEF GIF_SAFE}
    cmp   eax, GIFBufSize-1
    jle   @@suffix_good4
    and   eax, GIFBufSize-1
    mov   [Bad], 1
  @@suffix_good4:
    {$ENDIF}
    mov   byte ptr [Suffix+eax], dl
    mov   edx, [OldCode]
    {$IFDEF GIF_SAFE}
    cmp   edx, GIFBufSize-1
    jle   @@Prefix_good2
    and   edx, GIFBufSize-1
    mov   [Bad], 1
  @@Prefix_good2:
    {$ENDIF}
    mov   dword ptr [Prefix+eax*4], edx

    cmp   eax, [CodeMask]
    jnz   @@7
    cmp   cl, 12
    jae   @@7

    inc   cl
    xor   eax, eax
    inc   eax
    shl   eax, cl
    dec   eax
    mov   [CodeMask], eax

  @@7:
    cmp   [FreeCode], GIFBufSize-1
    jae   @@8
    inc   [FreeCode]

  @@8:
    mov   eax, [InCode]
    mov   [OldCode], eax

  @@9:
    {$IFDEF GIF_SAFE}
    test  ebx, ebx
    jz    @@stk_bad4
    dec   ebx
    mov   al, byte ptr [Stack+ebx]
    jmp   @@stk_good4
  @@stk_bad4:
    mov   [Bad], 1
  @@stk_good4:
    {$ELSE}
    dec   ebx
    mov   al, byte ptr [ebx]
    {$ENDIF}

    {$IFDEF GIF_LOG}
    pushad
    call  doGifLog2
    popad
    {$ENDIF}
    stosb
    dec   [UnpackedSize]
    {$IFDEF GIF_SAFE}
    test  ebx, ebx
    {$ELSE}
    cmp   ebx, [StackPointer]
    {$ENDIF}
    jne   @@9

    jmp   @@while

  @@e_while:
    inc   esi
    dec   [PackedSize]

    jmp   @@loop

  @@exit:
    pop  edi
    pop  esi
    pop  ebx
  end;