/* ** libinit.c ** 21st May 2000 ** David McMinn ** The basic library functions: init, open, close, expunge, extra */ #include #include #include #include #include #include #include #include #include #include "defs.h" #include "semaphores.h" #include "libinit.h" struct ExecBase *SysBase = NULL; /* pointer to exec.library */ SEGLISTPTR sl = NULL; /* pointer to the seglist of our library */ struct PPCBase *PowerPCBase = NULL; /* powerpc.library base */ struct Library *PPCLibBase = NULL; /* ppc.library base */ static VOID free_library_base( struct Library *lib_base, SEGLISTPTR seglist ); /* ** InitLib() ** ** Called by MakeResident() after library is LoadSeg'd ** INPUTS struct myLibBase *base (in D0) - Pointer to our library base SEGLISTPTR seglist (in A0) - Pointer to our seglist struct ExecBase *execbase - Pointer to exec.library base RESULT Pointer to our library base if everything was OK, or NULL for failure */ struct myLibBase * SAVEDS ASM InitLib(REG(d0) struct myLibBase *base, REG(a0) SEGLISTPTR seglist, REG(a6) struct ExecBase *execbase) { struct myLibBase *myLibBase = base; /* take backup copy of library base as d0 is a scratch register */ SysBase = execbase; /* store pointer to exec.library base */ sl = seglist; /* and also store our seglist pointer */ myLibBase->lb_pluginID = 0x504C5547; /* store 'PLUG' in library base to identify this as a Scalos plugin */ /* try to open ppc.library */ PPCLibBase = myLibBase->lb_PowerUPBase = (struct Library *)OpenLibrary("ppc.library", 0L); if(myLibBase->lb_Semaphore = CreateSemaphore()) { return(myLibBase); } free_library_base((struct Library *)myLibBase, sl); /* otherwise call function to free everything */ return(NULL); /* and return NULL for failure */ } /* ** OpenLib() - called on each OpenLibrary() INPUTS struct myLibBase *base (in A6) - Pointer to our library base RESULT Pointer to our library base if everything went OK, NULL for failure */ struct myLibBase * SAVEDS ASM OpenLib(REG(a6) struct myLibBase *base) { struct myLibBase *myLibBase = base; /* take working copy of our libbase pointer */ ObtainSemaphore(myLibBase->lb_Semaphore); /* Try to get exclusive access to the library base */ myLibBase->lb_LibNode.lib_OpenCnt++; /* Increase open count */ myLibBase->lb_LibNode.lib_Flags &= ~LIBF_DELEXP; /* Clear the delayed expunge flag */ ReleaseSemaphore(myLibBase->lb_Semaphore); return(myLibBase); } /* ** CloseLib() - called on every CloseLibrary() INPUTS struct myLibBase *base (in A6) - pointer to our library base RESULT Pointer to our seglist if the library is OK to be freed from memory or NULL if it should be left alone */ SEGLISTPTR SAVEDS ASM CloseLib(REG(a6) struct myLibBase *base) { struct myLibBase *myLibBase = base; /* copy of the pointer to our library base */ ObtainSemaphore(myLibBase->lb_Semaphore); /* try to get exclusive access to the library base */ myLibBase->lb_LibNode.lib_OpenCnt--; /* decrease number of tiems the library has been opened */ if(!myLibBase->lb_LibNode.lib_OpenCnt) /* if no-one else has opened this library */ { if(myLibBase->lb_LibNode.lib_Flags & LIBF_DELEXP) /* and the delayed expunge flag is set */ { ReleaseSemaphore(myLibBase->lb_Semaphore); return(ExpungeLib(myLibBase)); /* try to Expunge the library and return */ } } ReleaseSemaphore(myLibBase->lb_Semaphore); return(NULL); /* Return NULL, so don't free library from memory */ } /* ** ExpungeLib() - Called when library should be freed from memory INPUTS struct myLibBase *base (in A6) - pointer to our library base RESULT Pointer to our seglist if this library should be freed from memory or NULL if the library should not be freed from memory */ SEGLISTPTR SAVEDS ASM ExpungeLib(REG(a6) struct myLibBase *base) { struct myLibBase *myLibBase = base; /* take copy of pointer to our library base */ SEGLISTPTR seglist; /* copy of the pointer to our seglist */ ObtainSemaphore(myLibBase->lb_Semaphore); /* Get exclusive access to our library base */ if(!myLibBase->lb_LibNode.lib_OpenCnt) /* if no-one has this library open */ { ReleaseSemaphore(myLibBase->lb_Semaphore); /* release access to library base */ FreeSemaphore(myLibBase->lb_Semaphore); /* free semaphore used to grant access to library base */ /* Close all the libraries we have opened */ //if(myLibBase->lb_PowerPCBase) // CloseLibrary((struct Library *)myLibBase->lb_PowerPCBase); if(myLibBase->lb_PowerUPBase) CloseLibrary(myLibBase->lb_PowerUPBase); Remove((struct Node *)myLibBase); /* remove our library from the list of libraries */ seglist = sl; /* take copy of the seglist pointer (the next function sets it to NULL) */ /* Call function to free memory used by library */ free_library_base((struct Library *) myLibBase, seglist); return(seglist); /* return pointer to seglist, tell OS to remove it from memory */ } myLibBase->lb_LibNode.lib_Flags |= LIBF_DELEXP; /* else, set the delayed expunge flag */ ReleaseSemaphore(myLibBase->lb_Semaphore); /* release access to library base */ return(NULL); /* return NULL (tell OS not to remove us from memory */ } /* ** ExtFuncLib() - Extra library function, must return NULL */ ULONG SAVEDS ASM ExtFuncLib(void) { return(0); } /* ** free_library_base() - frees the memory taken up by the library base INPUTS struct Library *lib_base - pointer to the library base to free SEGLISTPTR seglist - pointer to our seglist */ static VOID free_library_base( struct Library *lib_base, SEGLISTPTR seglist ) { ULONG negsize; /* the size of memory that the library base extends to below the libbase pointer */ ULONG possize; /* memory used by the library base above the libbase pointer */ ULONG fullsize; /* the total size of the library base (the previous two added up) */ UBYTE *negptr = (UBYTE *) lib_base; /* pointer to the start of memory to be freed */ negsize = lib_base->lib_NegSize; /* get negative size of library base */ possize = lib_base->lib_PosSize; /* and positive size */ fullsize = negsize + possize; /* add them to get the total size of the libbase */ negptr -= negsize; /* alter the pointer to point to the start of the memory to be freed */ FreeMem( negptr, fullsize ); /* free the library base memory */ }