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Annotation of dmsdos/PORT_TO_WIN32, revision 1.1

1.1     ! root        1: Porting dmsdos to Win32
        !             2: -----------------------
        !             3: 
        !             4: If you want to use dmsdos under a 32 bit Microsoft Windows system such as
        !             5: Win95/98 or Win NT 4.0 there are two possibilities: try it at user level
        !             6: (easy) or at driver level (difficult but more interesting).
        !             7: 
        !             8: Don't try a 16 bit environment. You won't get it work as dmsdos needs more
        !             9: than 1MB of temporary memory. Buy the appropriate MS-DOS or Stacker version 
        !            10: instead. They're also faster because they are said to contain hand-optimized
        !            11: assembler code.
        !            12: 
        !            13: At least, there's no Win NT version of Doublespace, Drivespace or Stacker.
        !            14: This makes dmsdos somewhat interesting for Win32 :)
        !            15: 
        !            16: Well you can also try a 32 bit extended Dos environment such as DJGPP.
        !            17: 
        !            18: 
        !            19: A. User Level
        !            20: -------------
        !            21: 
        !            22: I tried, and I found Win32 programming is not fun. At least if you are
        !            23: used to programming in a Unix environment.
        !            24: 
        !            25: It _should_ be easy to compile libdmsdos and, for example, dcread under any 
        !            26: 32 bit environment. Well, I tried Win NT 4.0 with Cygnus' Win32 B19 version 
        !            27: of gcc, but almost nothing worked. The configure script, which runs under
        !            28: pure bash, didn't run with the bash found in that package. So what, I then
        !            29: configured dmsdos under Linux and copied the config files. With a lot of
        !            30: hacking, I finally managed to compile libdmsdos, but it was of no use.
        !            31: Whatever I did, when linking any dmsdos utility against the library I just 
        !            32: managed to crash the linker :(( 
        !            33: I have really no idea what stupid things I may have done...
        !            34: Looks like this gcc port is not yet ready for daily use. Sigh. Though it's 
        !            35: really an impressive work: all gnu tools under NT...
        !            36: 
        !            37: Okay, now Cygnus have released B20 version of their Win32 gcc port, and -
        !            38: guess what - it _worked_, almost out of the box. Even the Configure script
        !            39: runs correctly now. There is a special Makefile, Makefile.cygwinb20,
        !            40: that should be used for this compiler. One thing, though, is bad: the
        !            41: compiler does neither support Unix flock nor Win32 sopen. This means the
        !            42: generated code does not do file locking. Be sure that there is never
        !            43: more than one process that is using a CVF through libdmsdos.
        !            44: 
        !            45: The next chance I gave to Microsoft Visual C++ 5.0. Again almost nothing
        !            46: worked (and yes, the IDE also crashed awaking Dr. Watson when I just clicked
        !            47: around in the help in order to learn how to use the IDE...). No need to say
        !            48: that I had to configure dmsdos under Linux. The complete Makefile was even
        !            49: rejected by nmake. So what. I finally wrote a script win32_msc50.bat
        !            50: that compiles the necessary things in a Win32 _console_. Currently, the
        !            51: only useful application is mcdmsdos: it can extract files from a CVF in
        !            52: a Win32 environment. (Just tested: the executable runs even under wine in 
        !            53: an xterm :-) )
        !            54: 
        !            55: I did not try other compiler versions. It may work with the DJGPP Dos port 
        !            56: of gcc and the EMX OS/2 port of gcc. But you may find that the long filenames
        !            57: the dmsdos sources use cause a lot of problems there...
        !            58: Now there's a script called "prepare_dos_8.3" in the src directory that
        !            59: translates all relevant dmsdos files to use 8.3 names. There's no further
        !            60: documentation about this. You are expected to take a look at the script.
        !            61: You are also expected to write your own Makefile for compilation in such an
        !            62: environment. There are lots of problems that may occur in a DOS environment.
        !            63: Sorry, but I can't test everything.
        !            64: 
        !            65: Okay, that's what should work under every compiler:
        !            66: 
        !            67: * Configure, compile and install dmsdos under Linux.
        !            68: * Copy the whole directory where it compiled to a vfat partition.
        !            69: * Boot a Win32 system and edit the script win32_msc50.bat (on my system
        !            70:   I had to setup include and library paths there). If your compiler is not
        !            71:   Microsoft Visual C++ 5.0 this may not work and you may have to write
        !            72:   a new script from scratch.
        !            73: * Run the script with errors directed into a file.
        !            74: * Hack the source where it fails. Please be sure to surround your changes
        !            75:   with appropriate #ifdef's (unless they are real bugs) so I can integrate
        !            76:   them into next dmsdos release. Let me know what you had to change and why.
        !            77: 
        !            78: 
        !            79: B. Driver Level
        !            80: ---------------
        !            81: 
        !            82: That's indeed possible. At least, there has been some discussion about using
        !            83: libdmsdos for writing a Win95/98 VXD or a Win NT 4.0 FS driver.
        !            84: 
        !            85: Well, I refuse to do that. I'm not a Win32 driver hacker and my knowledge
        !            86: about the Win95/98 or Win NT driver interface is almost zero. But some
        !            87: notes may be interesting, though.
        !            88: 
        !            89: Note that libdmsdos is *not* reentrant. If the Win32 system does not ensure 
        !            90: exclusive execution of the driver code you must write your own *exclusive* 
        !            91: locking interface around all libdmsdos calls, even in read-only mode.
        !            92: 
        !            93: Beyond that, you will have to write a full-featured FAT filesystem
        !            94: driver that calls the libdmsdos cluster read and write routines, and link it
        !            95: against libdmsdos. That's almost all. That's not difficult.
        !            96: As FAT is a simple filesystem layout, and the CVFs are FAT12 or FAT16 but
        !            97: never FAT32, each experienced Dos programmer should be able to write that 
        !            98: from scratch, at least for 8.3 filenames which would be enough for 
        !            99: functionality :) The first trial is always read-only, and that should not be
        !           100: too much work.
        !           101: 
        !           102: Note that libdmsdos references some standard C library functions that are
        !           103: not available at driver level. You must write an emulation for all these 
        !           104: functions and link it to the driver instead of the standard C library. The 
        !           105: emulation needn't be full-featured like the C library. Look at the source 
        !           106: if you are in doubt. Well, the read/write/lseek emulation is actually all 
        !           107: the low-level disk access :)
        !           108: 
        !           109: See doc/libdmsdos.doc for further information about the dmsdos library
        !           110: (including a list of referrenced C library functions and a detailed
        !           111: description of the dmsdos functions the library exports).
        !           112: 
        !           113: Let me know if you are a Win32 hacker and want to start such a project :)

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