* -------------------------------------------------------------------- * Example CH12-8.s * -------------------------------------------------------------------- ; some system include files... include exec/types.i include exec/libraries.i include exec/exec_lib.i include dos/dos_lib.i * -------------------------------------------------------------------- ; external reference declarations... XREF _printf XREF _afp XREF _fpa EXTERN_LIB SPExp XDEF _stdout XDEF _DOSBase * -------------------------------------------------------------------- CALLSYS MACRO LINKLIB _LVO\1,\2 ENDM ; CALLSYS macro is used to extend LINKLIB and thus avoid the explicit ; use of the _LVO prefixes in the function names... * -------------------------------------------------------------------- ; general EQUate definitions... _AbsExecBase EQU 4 LF EQU 10 NULL EQU 0 * -------------------------------------------------------------------- ; error number EQUate definitions... NO_ERRORS EQU 0 NO_ARGUMENTS EQU 1 LONG_ARGUMENTS EQU 2 NO_MATHS EQU 3 NO_TRANS EQU 4 OVERFLOW EQU 5 * -------------------------------------------------------------------- ; program starts by checking size of CLI/Shell argument line... clr.b error_flag LBOUND cmpi.b #1,d0 bne UBOUND move.b #NO_ARGUMENTS,error_flag bra OPENDOS UBOUND cmpi.b #number_SIZEOF,d0 bls COPYARGS move.b #LONG_ARGUMENTS,error_flag bra OPENDOS COPYARGS lea number,a1 destination pointer subq.b #2,d0 disregard line terminator LOOP move.b (a0)+,(a1)+ copy string dbeq d0,LOOP move.b #NULL,(a1) NULL terminate string OPENDOS move.l _AbsExecBase,_SysBase set up SysBase lea dos_name,a1 and open DOS library moveq #0,d0 any version will do CALLSYS OpenLibrary,_SysBase macro (see text for details) move.l d0,_DOSBase store returned value beq EXIT test result for success ; if we reach here then the DOS library is open and its functions can ; be safely used! CALLSYS Output,_DOSBase get default output handle move.l d0,_stdout store output handle beq CLOSEDOS ; This next code is tricky unless you realize what is happening. The ; 68000 hasn't got conditional subroutine instructions so I create my ; own by pushing a return address on the stack and then conditionally ; BRANCHING to the appropriate subroutine. DOS_OPEN pea CLOSEDOS tst.b error_flag command line error? beq ARGS_OK next subroutine level rts CLOSEDOS tst.b error_flag were there any errors? beq CLOSEDOS1 skip error message if not jsr ErrorMsg CLOSEDOS1 move.l _DOSBase,a1 base needed in a1 CALLSYS CloseLibrary, _SysBase ; all done so exit back to CLI/Shell... EXIT clr.l d0 rts logical end of program * -------------------------------------------------------------------- ; Remember that this diagram level is coded as a subroutine ARGS_OK pea ARGS_OK1 push a return address jsr OpenMaths zero flag clear on failure beq MATHS_OPEN next subroutine level ARGS_OK1 rts twin execution - see text * -------------------------------------------------------------------- ; another diagram level coded as a subroutine MATHS_OPEN pea MATHS_OPEN1 push a return address jsr OpenTrans zero flag clear on failure beq TRANS_OPEN next subroutine level rts MATHS_OPEN1 jsr CloseMaths rts * -------------------------------------------------------------------- ; yet another diagram level coded as a subroutine and at this point the ; DOS, maths, and mathtrans libraries are open and useable... TRANS_OPEN pea TRANS_OPEN1 push return address pea number push pointer jsr _afp data comes back in d0 add.l #4,sp adjust stack CALLSYS SPExp,_MathTransBase values sent/returned in d0 bvc PRINT_DATA check for overflow move.b #OVERFLOW,error_flag rts TRANS_OPEN1 jsr CloseTrans rts * -------------------------------------------------------------------- ; lowest diagram level coded again as a subroutine PRINT_DATA pea result result already in d0 move.l d0,-(sp) push ffp value jsr _fpa convert back to ASCII addq.l #8,sp adjust stack pea result push sum string pointer pea string_format push format string address jsr _printf use amiga.lib printf() addq.l #8,sp shortcut way to adjust stack rts * -------------------------------------------------------------------- ; If OpenMaths() routine fails the zero flag will be CLEAR on return! OpenMaths lea math_name,a1 library name start in a1 moveq #0,d0 any version will do CALLSYS OpenLibrary,_SysBase macro (see text for details) move.l d0,_MathBase store returned value beq OpenMaths1 branch taken if open failed clr.l d0 open OK so set zero flag rts OpenMaths1 move.b #NO_MATHS,error_flag will CLEAR z flag rts * -------------------------------------------------------------------- ; If OpenTrans() routine fails the zero flag will be CLEAR on return! OpenTrans lea mathtrans_name,a1 library name start in a1 moveq #0,d0 any version will do CALLSYS OpenLibrary,_SysBase macro (see text for details) move.l d0,_MathTransBase store returned value beq OpenTrans1 branch taken if open failed clr.l d0 open OK so set zero flag rts OpenTrans1 move.b #NO_TRANS,error_flag will CLEAR z flag rts * -------------------------------------------------------------------- CloseMaths move.l _MathBase,a1 base needed in a1 CALLSYS CloseLibrary, _SysBase rts * -------------------------------------------------------------------- CloseTrans move.l _MathTransBase,a1 base needed in a1 CALLSYS CloseLibrary, _SysBase rts * -------------------------------------------------------------------- ; following routine uses the value present in error_number to identify ; the n'th address in a table of error message pointers... ErrorMsg clr.l d0 could contain garbage! move.b error_flag,d0 get error number lsl.l #2,d0 multiply by 4 move.l #error_table,a0 load table base address move.l 0(a0,d0.l),-(sp) push table entry contents pea string_format push format string jsr _printf print error message add.l #8,sp adjust stack rts * -------------------------------------------------------------------- ; variables and static data... _stdout ds.l 1 _SysBase ds.l 1 _DOSBase ds.l 1 _MathBase ds.l 1 _MathTransBase ds.l 1 error_flag ds.b 1 dos_name dc.b 'dos.library',NULL math_name dc.b 'mathffp.library',NULL mathtrans_name dc.b 'mathtrans.library',NULL error0 dc.b 'no errors',NULL error1 dc.b 'no value supplied',NULL error2 dc.b 'command string too long',NULL error3 dc.b 'could not open maths library',NULL error4 dc.b 'could not open mathtrans library',NULL error5 dc.b 'result produced an overflow',NULL string_format dc.b '%s',LF,NULL EVEN number ds.b 32 number_SIZEOF EQU *-number result ds.b 16 error_table dc.l error0,error1,error2,error3,error4,error5 * --------------------------------------------------------------------