  <chapter id="implementation">
    <title>Low-level Implementation</title>
    <para>Details of Wine's Low-level Implementation...</para>

    <sect1 id="builtin-dlls">
      <title>Builtin DLLs</title>

      <para>
        Written by &name-juergen-schmied; <email>&email-juergen-schmied;</email>
      </para>
      <para>
        (Extracted from <filename>wine/documentation/internal-dll</filename>)
      </para>

      <para>
        This document describes some points you should know before
        implementing the internal counterparts to external DLL's.
        Only 32 bit DLL's are considered.
      </para>

      <sect2>
        <title>1. The LibMain function</title>

        <para>
          This is the way to do some initializing when a process or
          thread is attached to the DLL. The function name is taken
          from a <filename>*.spec</filename> file line:
        </para>
        <programlisting>
init    YourFunctionName
        </programlisting>
        <para>
          Then, you have to implement the function:
        </para>
        <programlisting>
BOOL32 WINAPI YourLibMain(HINSTANCE32 hinstDLL,
			 DWORD fdwReason, LPVOID lpvReserved)
{ if (fdwReason==DLL_PROCESS_ATTACH)
  { ...
  } 
  ....
}
        </programlisting>
      </sect2>

      <sect2>
        <title>2. Using functions from other built-in DLL's</title>

        <para>
          The problem here is, that you can't know if you have to call
          the function from the internal or the external DLL. If you
          just call the function you will get the internal
          implementation. If the external DLL is loaded the executed
          program will use the external DLL and you the internal one.
          When you -as an example- fill an iconlist placed in the
          internal DLL the application won't get the icons from the
          external DLL.
        </para>
        <para>
          To work around this, you should always use a pointer to call
          such functions:
        </para>
        <programlisting>
/* definition of the pointer type*/
void (CALLBACK* pDLLInitComctl)();

/* getting the function address  this should be done in the
 LibMain function when called with DLL_PROCESS_ATTACH*/
 
BOOL32 WINAPI Shell32LibMain(HINSTANCE32 hinstDLL, DWORD fdwReason,
							 LPVOID lpvReserved)
{ HINSTANCE32 hComctl32;
  if (fdwReason==DLL_PROCESS_ATTACH)
  { /* load the external / internal DLL*/
    hComctl32 = LoadLibrary32A("COMCTL32.DLL"); 
    if (hComctl32)
    { /* get the function pointer */
      pDLLInitComctl=GetProcAddress32(hComctl32,"InitCommonControlsEx");

	  /* check it */
      if (pDLLInitComctl)
      { /* use it */
        pDLLInitComctl();
      }
      
      /* free the DLL / decrease the ref count */
      FreeLibrary32(hComctl32);
    }
    else
    { /* do some panic*/
      ERR(shell,"P A N I C error getting functionpointers\n");
      exit (1);
    }
  }
 ....
        </programlisting>
      </sect2>

      <sect2>
        <title>3. Getting resources from a <filename>*.rc</filename> file linked to the DLL</title>

        <para>
          &lt; If you know how, write some lines&gt;
        </para>
      </sect2>
    </sect1>

    <sect1 id="accel-impl">
      <title>Accelerators</title>

      <para>
        Findings researched by Uwe Bonnes, Ulrich Weigand and Marcus Meissner.
      </para>
      <para>
        (Extracted from <filename>wine/documentation/accelerators</filename>)
      </para>

      <para>
        Some notes concerning accelerators.
      </para>
      <para>
        There are <emphasis>three</emphasis> differently sized
        accelerator structures exposed to the user. The general layout
        is:
      </para>
      <programlisting>
BYTE   fVirt;
WORD   key;
WORD   cmd;
      </programlisting>
      <para>
        We now have three different appearances:
      </para>

      <orderedlist>
        <listitem>
          <para>
            Accelerators in NE resources. These have a size of 5 byte
            and do not have any padding. This is also the internal
            layout of the global handle <type>HACCEL</type> (16 and
            32) in Windows 95 and Wine. Exposed to the user as Win16
            global handles <type>HACCEL16</type> and
            <type>HACCEL32</type> by the Win16/Win32 API.
          </para>
        </listitem>
        <listitem>
          <para>
            Accelerators in PE resources. These have a size of 8 byte.
            Layout is:
          </para>
          <programlisting>
BYTE   fVirt;
BYTE   pad0;
WORD   key;
WORD   cmd;
WORD   pad1;
          </programlisting>
          <para>
            They are exposed to the user only by direct accessing PE
            resources.
          </para>
        </listitem>
        <listitem>
          <para>
            Accelerators in the Win32 API. These have a size of 6
            bytes. Layout is:
          </para>
          <programlisting>
BYTE   fVirt;
BYTE   pad0;
WORD   key;
WORD   cmd;
          </programlisting>
          <para>
            These are exposed to the user by the
            <function>CopyAcceleratorTable</function> and
            <function>CreateAcceleratorTable</function> functions in
            the Win32 API.
          </para>
        </listitem>
      </orderedlist>

      <para>
        Why two types of accelerators in the Win32 API? We can only
        guess, but my best bet is that the Win32 resource compiler
        can/does not handle struct packing. Win32 <type>ACCEL</type>
        is defined using <function>#pragma(2)</function> for the
        compiler but without any packing for RC, so it will assume
        <function>#pragma(4)</function>.
      </para>

    </sect1>

    <sect1 id="file-handles">
      <title>File Handles</title>

      <para>
        Written by (???)
      </para>
      <para>
        (Extracted from <filename>wine/documentation/filehandles</filename>)
      </para>

      <para>
        DOS treats the first 5 file handles as special cases.  They
        map directly to <filename>stdin</filename>,
        <filename>stdout</filename>, <filename>stderr</filename>,
        <filename>stdaux</filename> and <filename>stdprn</filename>.
        Windows 16 inherits this behavior, and in fact, win16 handles
        are interchangeable with DOS handles. Some nasty windows
        programs even do this!
      </para>
      <para>
        Windows32 issues file handles starting from
        <literal>1</literal>, on the grounds that most GUI processes
        don't need a <filename>stdin</filename>,
        <filename>stdout</filename>, etc.
      </para>
      <para>
        The Wine handle code is implemented in the Win32 style, and
        the Win16 functions use two macros to convert to and from the
        two types.
      </para>

      <para>
        The macros are defined in <filename>file.h</filename> as follows:
      </para>
      <programlisting>
#define HFILE16_TO_HFILE32(handle) \
(((handle)==0) ? GetStdHandle(STD_INPUT_HANDLE) : \
 ((handle)==1) ? GetStdHandle(STD_OUTPUT_HANDLE) : \
 ((handle)==2) ? GetStdHandle(STD_ERROR_HANDLE) : \
 ((handle)>0x400) ? handle : \
 (handle)-5)

#define HFILE32_TO_HFILE16(handle) ({ HFILE32 hnd=handle; \
      ((hnd==HFILE_ERROR32) ? HFILE_ERROR16 : \
      ((handle>0x400) ? handle : \
       (HFILE16)hnd+5); })
      </programlisting>

      <warning>
        <para>
          Be careful not to use the macro
          <function>HFILE16_TO_HFILE32</function> on functions with
          side-effects, as it will cause them to be evaluated several
          times.  This could be considered a bug, but the use of this
          macro is limited enough not to need a rewrite.
        </para>
      </warning>
      <note>
        <para>
          The <literal>0x400</literal> special case above deals with
          LZW filehandles (see <filename>misc/lzexpand.c</filename>).
        </para>
      </note>
    </sect1>

    <sect1 id="hardware-trace">
      <title>Doing A Hardware Trace In Wine</title>

      <para>
        Written by &name-jonathan-buzzard; <email>&email-jonathan-buzzard;</email>
      </para>
      <para>
        (Extracted from <filename>wine/documentation/ioport-trace-hints</filename>)
      </para>

      <para>
        The primary reason to do this is to reverse engineer a
        hardware device for which you don't have documentation, but
        can get to work under Wine.
      </para>
      <para>
        This lot is aimed at parallel port devices, and in particular
        parallel port scanners which are now so cheap they are
        virtually being given away. The problem is that few
        manufactures will release any programming information which
        prevents drivers being written for Sane, and the traditional
        technique of using DOSemu to produce the traces does not work
        as the scanners invariably only have drivers for Windows.
      </para>
      <para>
        Please note that I have not been able to get my scanner
        working properly (a UMAX Astra 600P), but a couple of people
        have reported success with at least the Artec AS6e scanner. I
        am not in the process of developing any driver nor do I intend
        to, so don't bug me about it. My time is now spent writing
        programs to set things like battery save options under Linux
        on Toshiba laptops, and as such I don't have any spare time
        for writing a driver for a parallel port scanner etc.
      </para>
      <para>
        Presuming that you have compiled and installed wine the first
        thing to do is is to enable direct hardware access to your
        parallel port. To do this edit <filename>wine.conf</filename>
        (usually in <filename>/usr/local/etc</filename>) and in the
        ports section add the following two lines
      </para>
      <programlisting>
read=0x378,0x379,0x37a,0x37c,0x77a
write=0x378,x379,0x37a,0x37c,0x77a
      </programlisting>
      <para>
        This adds the necessary access required for SPP/PS2/EPP/ECP
        parallel port on LPT1. You will need to adjust these number
        accordingly if your parallel port is on LPT2 or LPT0.
      </para>
      <para>
        When starting wine use the following command line, where
        <literal>XXXX</literal> is the program you need to run in
        order to access your scanner, and <literal>YYYY</literal> is
        the file your trace will be stored in:
      </para>
      <programlisting>
wine -debugmsg +io XXXX 2&gt; &gt;(sed 's/^[^:]*:io:[^ ]* //' &gt; YYYY)
      </programlisting>
      <para>
        You will need large amounts of hard disk space (read hundreds
        of megabytes if you do a full page scan), and for reasonable
        performance a really fast processor and lots of RAM.
      </para>
      <para>
        You might well find the log compression program that <email>David
        Campbell campbell@torque.net</email> wrote helpful in
        reducing the size of the log files. This can be obtained by
        the following command:
      </para>
      <programlisting>
sh ioport-trace-hints
      </programlisting>
      <para>
        This should extract <filename>shrink.c</filename> (which is
        located at the end of this file. Compile the log compression
        program by:
      </para>
      <programlisting>
cc shrink.c -o shrink
      </programlisting>
      <para>
        Use the <command>shrink</command> program to reduce the
        physical size of the raw log as follows:
      </para>
      <programlisting>
cat log | shrink &gt; log2
      </programlisting>
      <para>
        The trace has the basic form of
      </para>
      <programlisting>
XXXX &gt; YY @ ZZZZ:ZZZZ
      </programlisting>
      <para>
        where <literal>XXXX</literal> is the port in hexidecimal being
        accessed, <literal>YY</literal> is the data written (or read)
        from the port, and <literal>ZZZZ:ZZZZ</literal> is the address
        in memory of the instruction that accessed the port. The
        direction of the arrow indicates whether the data was written
        or read from the port.
      </para>
      <programlisting>
&gt; data was written to the port
&lt; data was read from the port
      </programlisting>
      <para>
        My basic tip for interpreting these logs is to pay close
        attention to the addresses of the IO instructions. Their
        grouping and sometimes proximity should reveal the presence of
        subroutines in the driver. By studying the different versions
        you should be able to work them out. For example consider the
        following section of trace from my UMAX Astra 600P
      </para>
      <programlisting>
0x378 &gt; 55 @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
0x378 &gt; aa @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
0x378 &gt; 00 @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
0x378 &gt; 00 @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
0x378 &gt; 00 @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
0x378 &gt; 00 @ 0297:01ec
0x37a &gt; 05 @ 0297:01f5
0x379 &lt; 8f @ 0297:01fa
0x37a &gt; 04 @ 0297:0211
      </programlisting>
      <para>
        As you can see there is a repeating structure starting at
        address <literal>0297:01ec</literal> that consists of four io
        accesses on the parallel port. Looking at it the first io
        access writes a changing byte to the data port the second
        always writes the byte <literal>0x05</literal> to the control
        port, then a value which always seems to
        <literal>0x8f</literal> is read from the status port at which
        point a byte <literal>0x04</literal> is written to the control
        port. By studying this and other sections of the trace we can
        write a C routine that emulates this, shown below with some
        macros to make reading/writing on the parallel port easier to
        read.
      </para>
      <programlisting>
#define r_dtr(x)        inb(x)
#define r_str(x)        inb(x+1)
#define r_ctr(x)        inb(x+2)
#define w_dtr(x,y)      outb(y, x)
#define w_str(x,y)      outb(y, x+1)
#define w_ctr(x,y)      outb(y, x+2)

/*
 * Seems to be sending a command byte to the scanner
 *
 */
int udpp_put(int udpp_base, unsigned char command)
{
        int loop,value;

        w_dtr(udpp_base, command);
        w_ctr(udpp_base, 0x05);

        for (loop=0;loop&lt;10;loop++)
                if (((value=r_str(udpp_base)) & 0x80)!=0x00) {
                        w_ctr(udpp_base, 0x04);
                        return value & 0xf8;
                        }

        return (value & 0xf8) | 0x01;
}
      </programlisting>
      <para>
        For the UMAX Astra 600P only seven such routines exist (well
        14 really, seven for SPP and seven for EPP). Whether you
        choose to disassemble the driver at this point to verify the
        routines is your own choice. If you do, the address from the
        trace should help in locating them in the disassembly.
      </para>
      <para>
        You will probably then find it useful to write a script/perl/C
        program to analyse the logfile and decode them futher as this
        can reveal higher level grouping of the low level routines.
        For example from the logs from my UMAX Astra 600P when decoded
        further reveal (this is a small snippet)
      </para>
      <programlisting>
start:
put: 55 8f
put: aa 8f
put: 00 8f
put: 00 8f
put: 00 8f
put: c2 8f
wait: ff
get: af,87
wait: ff
get: af,87
end: cc
start:
put: 55 8f
put: aa 8f
put: 00 8f
put: 03 8f
put: 05 8f
put: 84 8f
wait: ff
      </programlisting>
      <para>
        From this it is easy to see that <varname>put</varname>
        routine is often grouped together in five successive calls
        sending information to the scanner. Once these are understood
        it should be possible to process the logs further to show the
        higher level routines in an easy to see format. Once the
        highest level format that you can derive from this process is
        understood, you then need to produce a series of scans varying
        only one parameter between them, so you can discover how to
        set the various parameters for the scanner.
      </para>

      <para>
        The following is the <filename>shrink.c</filename> program.
      </para>

      <programlisting>
cat &gt; shrink.c &lt;&lt;EOF
#include &lt;stdio.h&gt;
#include &lt;string.h&gt;

void 
main (void)
{
  char buff[256], lastline[256];
  int count;

  count = 0;
  lastline[0] = 0;

  while (!feof (stdin))
    {
      fgets (buff, sizeof (buff), stdin);
      if (strcmp (buff, lastline) == 0)
	{
	  count++;
	}
      else
	{
	  if (count &gt; 1)
	    fprintf (stdout, "# Last line repeated %i times #\n", count);
	  fprintf (stdout, "%s", buff);
	  strcpy (lastline, buff);
	    count = 1;
	}
    }
}
EOF
      </programlisting>
    </sect1>

  </chapter>

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