104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/*
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* Use compiler specific key words to set up shareable library
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* external symbols and entry points
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*
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* Right now this is only necessary for WIN32 DLL,
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* the approach should be general enough for future systems, however.
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*
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*
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* USAGE:
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*
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* In header files, declare variables, classes and functions
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* to be __exported__ like this:
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*
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* epicsShareFunc int epicsShareAPI
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* a_func (int arg); function prototype
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* epicsShareExtern int a_var; reference variable
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* epicsShareDef int a_var= 4; create variable instance
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* class epicsShareClass a_class; reference a class
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*
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* Usually the epicsShare... macros expand to
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* "import this from a DLL" (on WIN32, on Unix it's a NOP)
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*
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* In the implementation file, however, you write:
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*
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* #include <other_stuff.h>
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* #define epicsExportSharedSymbols
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* #include <shareLib.h>
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* #include <what_I_implement.h>
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* ! no more "foreign" includes from here on !
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*
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* The point is: define epicsExportSharedSymbols exacly and only
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* right before you include the prototypes for what you implement!
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* Then include shareLib.h again because this is where they get changed.
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* This time the epicsShare... macros expand to
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* "export this from the DLL that we are building". (again only on WIN32)
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*
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* 8-22-96 -kuk-
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*/
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#undef epicsShareExtern
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#undef epicsShareDef
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#undef epicsShareClass
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#undef epicsShareFunc
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#undef epicsShareAPI
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#undef READONLY
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#if defined(_WIN32)
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# if defined(epicsExportSharedSymbols)
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# define epicsShareExtern extern __declspec(dllexport)
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# define epicsShareClass __declspec(dllexport)
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# define epicsShareFunc __declspec(dllexport)
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# else
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# define epicsShareExtern extern __declspec(dllimport)
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# define epicsShareClass __declspec(dllimport)
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# define epicsShareFunc __declspec(dllimport)
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# endif
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/*
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* Subroutine removes arguments
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* (Bill does not allow __stdcall to be next to
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* __declspec(xxxx))
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*/
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# define epicsShareAPI __stdcall
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# define epicsShareDef __declspec(dllexport)
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# define READONLY const
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#elif defined(VAXC)
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/*
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* VAXC creates FORTRAN common blocks when
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* we use "extern int fred"/"int fred=4". Therefore,
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* the initialization is not loaded unless we
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* call a function in that object module.
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*
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* DEC CXX does not have this problem.
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* We suspect (but do not know) that DEC C
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* also does not have this problem.
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*/
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# define epicsShareExtern globalref
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# define epicsShareDef globaldef
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# define READONLY const
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# define epicsShareClass
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# define epicsShareFunc
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# define epicsShareAPI
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#else
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/* else => no import/export specifiers */
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# define epicsShareExtern extern
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# define epicsShareAPI
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# define epicsShareClass
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# define epicsShareDef
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# define epicsShareFunc
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# if defined(__STDC__)
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# define READONLY const
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# else
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# define READONLY
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# endif
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#endif
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