* == rxexample.asm ===================================================== * * Copyright (c) 1987 by William S. Hawes (All Rights Reserved) * * ====================================================================== * An example of an external function library for use with ARexx. Defines * the required Open, Close, Expuncge, and reserved entry points, and loads * the arguments for calling the'C' language Dispatch() function. * * The initialization code opens the ARexx systems library and places the * library base in the external _RexxSysBase, and places this library base * in the external RexxExmpBase. * * N.B. The convention for loading the 'C' language static data pointer into * register A4 differs between compilers. The present code loads A4 using * the linker (BLINK) defined value _LinkerDB; this will have to be changed * to use the Manx 'C' compiler. Also note that calls to the library MUST * preserve all regisrers except for A0/A1 and D0/D1; make sure that your * compiler observes this! IDNT RxExample SECTION RxExample,CODE NOLIST INCLUDE "rxexample.i" INCLUDE "exec/resident.i" INCLUDE "exec/initializers.i" LIST XREF _LinkerDB ; linker-defined static data pointer XREF _RexxSysBase ; user-defined library base XREF _RexxExmpBase ; user-defined library base XREF _Dispatch ; 'C' language dispatcher ; EXEC library entry points XLIB CloseLibrary XLIB FreeMem XLIB OpenLibrary XLIB Remove * First executable location Start: moveq #0,d0 rts LibPRI: EQU 0 ; priority field * the "romtag" structure follows romtag: dc.w RTC_MATCHWORD ; a magic word dc.l romtag ; insurance dc.l EndCode ; end marker for checksum dc.b RTF_AUTOINIT dc.b RXEVERS ; the Version number dc.b NT_LIBRARY dc.b LibPRI ; initialization priority dc.l RXELib ; the library name dc.l RXEId ; an ID string dc.l Init ; initialization table CNOP 0,4 Init: dc.l re_SIZEOF dc.l FuncTable dc.l DataTable dc.l InitEntry * Entry point addresses go here, in the jump table order FuncTable: dc.l Open ; required entry point dc.l Close ; required dc.l Expunge ; required dc.l Null ; reserved dc.l Dispatch ; 'Query' entry dc.l -1 ; table end marker * Initializers for the allocated library structure DataTable: INITBYTE LN_TYPE,NT_LIBRARY INITLONG LN_NAME,RXELib INITBYTE LIB_FLAGS,(LIBF_SUMUSED!LIBF_CHANGED) INITWORD LIB_VERSION,RXEVERS INITWORD LIB_REVISION,RXEREV INITLONG LIB_IDSTRING,RXEId dc.l 0 * This routine is called after the library has been loaded. The library * pointer is returned if no initialization errors occur. * Registers: A0 -- the segment list (from DOS) * A6 -- the Exec base * D0 -- the library pointer InitEntry: move.l a5,-(sp) movea.l d0,a5 move.l a6,re_SysBase(a5) ; save the Exec base address move.l a0,re_SegList(a5) ; save our SegList pointer ; Open the required libraries. lea RXSLib(pc),a1 ; library name moveq #RXSVERS,d0 ; version CALLSYS OpenLibrary move.l d0,_RexxSysBase move.l d0,re_REXXBase(a5) ; opened? beq.s 1$ ; no -- error move.l a5,d0 move.l a5,_RexxExmpBase 1$: movea.l (sp)+,a5 rts * ============================ Open ============================= * Increments the open count and returns the library pointer. * Registers: A6 -- library base * Return: D0 -- library base or 0 Open: addq.w #1,LIB_OPENCNT(a6) ; increment open count bclr #LIBB_DELEXP,LIB_FLAGS(a6) ; prevent delayed expunge move.l a6,d0 ; return the library base rts * ============================ Close ============================= * Decrements the open count, and checks whether the library is still open. * If not, and if a 'delayed expunge' is pending, it is expunged. * Registers: A6 -- library base * Return: D0 -- seglist or 0 Close: moveq #0,d0 ; default return subq.w #1,LIB_OPENCNT(a6) ; still open? bne.s 1$ ; yes ... ; Check whether to expunge the library. A closed library is ; normally left in memory in case someone else opens it. btst #LIBB_DELEXP,LIB_FLAGS(a6) ; a delayed expunge? beq.s 1$ ; no ... hold off bsr.s Expunge ; yes -- expunge it 1$: rts * ========================== Expunge ============================ * If the library is still open, the 'delayed expunge' flag is set, but the * library is left in memory. * Registers: A6 -- library base * Return: D0 -- seglist or 0 Expunge: tst.w LIB_OPENCNT(a6) ; library still open? beq.s 1$ ; no ... bset #LIBB_DELEXP,LIB_FLAGS(a6) ; set 'delayed expunge' moveq #0,d0 ; no seglist bra.s 2$ 1$: move.l re_SegList(a6),d0 ; the seglist movem.l d0/a5/a6,-(sp) movea.l a6,a5 ; Support base movea.l re_SysBase(a5),a6 ; get Exec base pointer movea.l a5,a1 CALLSYS Remove ; unlink us ; Close the external libraries that were opened ... movea.l re_REXXBase(a5),a1 CALLSYS CloseLibrary ; Calculate the size of the library node and release it. movea.l a5,a1 ; node moveq #0,d0 move.w LIB_NEGSIZE(a5),d0 ; forward extent suba.w d0,a1 ; low memory extent add.w LIB_POSSIZE(a5),d0 ; total length CALLSYS FreeMem ; give it back movem.l (sp)+,d0/a5/a6 ; seglist=>D0 2$: rts Null: moveq #0,d0 ; reserved entry rts ; The 'dispatch' function ... pushes args and calls 'C' function. ; Must return an error code in D0 and a result string in A0. Dispatch: move.l a4,-(sp) subq.l #4,sp ; Load the pointer to the global data area (generated by BLINK) lea _LinkerDB,a4 ; global pointer ; Call the function move.l sp,-(sp) ; push return pointer move.l a0,-(sp) ; push argument jsr _Dispatch ; D0=error code addq.l #8,sp ; restore stack movea.l (sp)+,a0 ; result string movea.l (sp)+,a4 rts RXELib: RXENAME ; the library name RXEId: RXEID ; an ID string RXSLib: RXSNAME ; ARexx Systems library CNOP 0,2 EndCode: ; a mysterious marker END