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Annotation of os2sdk/demos/examples/dynlink/readme, revision 1.1

1.1     ! root        1: 
        !             2: This directory contains illustrations of the creation and use of dynamic link
        !             3: libraries.  The library itself is constructed in one of two different ways:
        !             4: 
        !             5:     1. entirely in assembly code
        !             6:     2. nearly all in C, with an assembly stub module
        !             7: 
        !             8: The initialization entry point to the dynalink library must be defined in
        !             9: an assembly module, which can contain all of its own code or can make
        !            10: a call to a routine in a C module.
        !            11: 
        !            12: Your library can have several data segments, each which is global (SHARED)
        !            13: to all applications using the library or is duplicated (NONSHARED) for each
        !            14: application.  An example would be a pseudo graphics driver.  The
        !            15: "per-instance" data could be structures representing windows owned by each
        !            16: application.  The global data could be semaphores used to serialize access to
        !            17: the hardware.
        !            18: 
        !            19: -------------------------------------------------------------------------------
        !            20: The application:
        !            21: 
        !            22: There are two methods of linking to a dynamic link library:
        !            23: 
        !            24:     1. at load time
        !            25:     2. at run time
        !            26: 
        !            27: The first method is less complicated in that the system takes care of
        !            28: all fixup and loading of the library.  The second method is more
        !            29: comprehensive in that it allows the application to determine if a library
        !            30: exists, and make a choice of whether or not to use it.
        !            31: 
        !            32: The latter would be preferred in applications that need to run in environments
        !            33: lacking in certain libraries.  For example, a package could make good use of
        !            34: a fancy high resolution graphics board.  However, if the product wasn't
        !            35: present the application could fall back to the standard VIO graphics (such as
        !            36: they are).
        !            37: 
        !            38: There are two ways of linking an application so that it can link to a dynalink
        !            39: library at load time:
        !            40: 
        !            41:     1. the application can have a .DEF file which names the entry points
        !            42:        of the dynalink library used by it
        !            43:     2. IMPLIB can be used to create an IMPORTS library from the .DEF file
        !            44:        of the dynalink library
        !            45: 
        !            46: The second method does away with the need for the application to define
        !            47: a .DEF file.
        !            48: 
        !            49: -------------------------------------------------------------------------------
        !            50: 
        !            51: readme         this file
        !            52: 
        !            53: dynlink.cmd    front end for "make dynlink"
        !            54: 
        !            55:                    Sets up the environment for constructing the dll either
        !            56:                    from C modules ("dynlink c") or from the asm module
        !            57:                    ("dynlink asm"), then invokes "make dynlink".
        !            58: 
        !            59: dynlink        makefile
        !            60: 
        !            61:                    NB - The LIB and INCLUDE environment variables must be
        !            62:                    set correctly.  LIB is the search path for LINK and
        !            63:                    INCLUDE is the search path for CL.
        !            64: 
        !            65:                    NB - LIBPATH can be set (in CONFIG.SYS) to start in the
        !            66:                    current directory. eg. LIBPATH=.;C:\;C:\LIB
        !            67: 
        !            68: dynlib.h       defines calling conventions for the library routines
        !            69: 
        !            70: dynlib.def     contains library information for the linker and loader
        !            71: 
        !            72:                    This file is used to create the import library for the dll.
        !            73: 
        !            74: dyninit.asm    contains initialization routine entry point
        !            75: dynlib.c       data segment is per-instance
        !            76: dynlib2.c      data segment is global
        !            77: 
        !            78: near           subdirectory with C modules where data is not declared far
        !            79: far            subdirectory containing the far-data versions of the C modules
        !            80: 
        !            81:                    NB - Both near & far assume small-model compilation.
        !            82: 
        !            83: dynlib3.asm    assembly version
        !            84: 
        !            85: dynlink.def    IMPORTs the entry points of the dll
        !            86: 
        !            87: dynlink1.c     links to the dll at load time
        !            88: dynlink2.c     links to the dll at run time
        !            89: 
        !            90: dyngo.cmd      brings up several copies of dyndemo2.exe
        !            91: 
        !            92:                    NB - LIBPATH must contain the root directory.
        !            93: 
        !            94: dyncvp.cmd     brings up CodeView
        !            95: 
        !            96:                    NB - If you want to single-step the program, you must
        !            97:                    (with the cvp I am using, MS cvp v.2.00.10) use the
        !            98:                    right mouse button to execute to the next instruction,
        !            99:                    immediately upon entering cvp.  Then you can use F8
        !           100:                    to single-step to your heart's content.
        !           101:                         Also, for the time being, cvp requires that your
        !           102:                    dll reside in the root directory of your boot disk.
        !           103:                    This requirement will go away.

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