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Volume Number: | 4 | |
Issue Number: | 11 | |
Column Tag: | Forth Forum |
Code Segments & Linker
By Jörg Langowski, MacTutor Editorial Board
Code segments and a Mach 2 linker
This month I’d like to report on some recent Mach2 improvements: the new 2.14 version and a linker for kernel-independent applications that has recently appeared on the GEnie Mach2 roundtable. Since many of you don’t have access to that BBS, I’ll document the linker here, with some review of code segment structure, and put the code on the source code disk.
Single-segment linker
We have seen several examples - DAs, XCMDs, MDEFs - of Mach2 code that runs independent of the Forth multitasking kernel. Writing such code requires that the programmer write the setup code that is usually provided by the Mach2 system. For the examples that I gave in my column, the standard glue code for making a routine callable from outside Mach2 looked similar to:
CODE prelude LINK A6,#-Nstack \ Nstack bytes of local Forth stack MOVEM.L A0-A5/D0-D7,-(A7)\ save registers MOVE.L A6,A3 \ setup local loop return stack SUBA.L #Nlocal,A3 \ in the low Nlocal stack bytes MOVE.L 8(A6),D0 \ pointer to parameter block MOVE.L D0,-(A6) RTS \ just to indicate the MACHro stops here END-CODE MACH CODE epilogue MOVEM.L (A7)+,A0-A5/D0-D7\ restore registers UNLK A6 MOVE.L (A7)+,A0 \ return address ADD.W #4,A7 \ pop off 4 bytes of parameters JMP (A0) RTS END-CODE MACH : my-forth-code ( code to be called externally ) ; : ext.routine prelude my-forth-code epilogue ;
After these definitions, the routine ext.routine may be called from the outside as if defined in Pascal as:
procedure ext.routine (parameter:longint); begin ( code to be called externally ) end;
All we need in this case before calling our Forth code is to set up a local Forth stack maintained by the A6 register, save all the registers for safety, and create a loop return stack maintained by A3.
In principle, a complete application can be created this way; however, some more setup is required. A simple one-segment application consists of two CODE resources: the jump table in CODE 0 and the actual code in CODE 1. The structure of the jump table (JT) as given in IM II-60 looks like the following (in the case that the first entry in the JT corresponds to a routine in segment 1):
0: longintAbove A5 size ( 32 + length of JT ) 4: longintBelow A5 size (appl. and QD globals) 8: longintLength of jump table in bytes 12:longint Offset from A5 to jump table (32 ) 16:Jump table: ------ Jump table entry #1 ------ word offset of routine #1 from beginning of segment longintMOVE.W #1,-(A7) ( push segment # of routine on stack) word _LoadSeg ------ following jump table entries ---- ------ for routine #2...n, if necessary ------
When an application is launched, the CODE 0 resource will be loaded and the first JT entry executed. This will load the appropriate segment into memory and jump to the routine to which the first entry is pointing. Thus, a simple one-segment application would consist of a CODE 0 resource like above, with one single JT entry:
$nnnn ( entry address in CODE 1 segment ) ( attention: segment starts at ) ( beginning of resource + 4) $3F3C0001( MOVE.W #1,-(A7) ) $A9F0 ( _LoadSeg )
CODE 1 would contain the actual code, written in Mach2.
What are the advantages of creating single-segment Mach2 programs? First of all, we can create very small applications. The smallest conceivable application, which does absolutely nothing but return, would comprise only 30 bytes:
CODE 0: $00000028( always $20 + length(JT) ) $00000200( arbitrary ) $00000008( length of JT; one entry ) $00000020( always ) $0000 ( entry address in CODE 1 segment ) $3F3C0001( MOVE.W #1,-(A7) ) $A9F0 ( _LoadSeg ) CODE 1: $0000 ( first routine is at beginning of JT ) $0001 ( one entry in this segment ) $4E75 ( RTS )
This program is enclosed on the source code disk as a curiosity. The file actually is 364 bytes long (Resource map etc.), which is still pretty small.
A second advantage is that we have complete control over the way the application sets itself up. In particular, we could pass a routine pointer to _InitDialogs to activate the Resume button of the system bomb box, or we might want to control the amount of calls to _MoreMasters.
The disadvantage of compiling applications under Mach2: Obviously we have to care about all the things that the kernel normally does for us, like basic event handling, menu and menu bar setup, screen input/output, etc. Particularly, there are quite a few Forth words that may not be used anymore; regular readers of this column should be familiar with the rules for creating ‘kernel-independent code’ that I’ve laid out a few times already.
The Forth words that can be used include:
! “ + +! ^ +> - -> 0< 0= 0> 1+ 1- 2* 2+ 2- 2/ 2DROP 2DUP 2OVER < <> = > >BODY >R ?DUP @ ABS AND ASCII C! C@ DROP DUP EXIT I I’ J LEAVE L_EXT NEGATE NOT OR OVER PAD PICK R> R@ SWAP U< W! W@ XOR { (it’s OK to use local variables)
The following control and branching structures may also be used:
IF ELSE THEN BEGIN WHILE REPEAT UNTIL AGAIN CASE ENDCASE OF ENDOF DO LOOP +LOOP
Assembler, of course, may be used freely.
Waymen Askey, of Palo Alto Shipping, has created a ‘linker’ utility that compiles single-segment application using the strategy given above. We reprint his program in listing 1 with his permission. This linker operates on a program which has the following structure:
PROGRAM programname; ( definitions not to be included in the final application such as constants, compiling words, etc. ) VAR ( global variable declarations which will be offset from A5 ) PROCEDURES ( Forth words called by the top level word ) MAIN ( top level word which is called on startup. ) ( This word should call the setup procedures ) ( MachSetUp and MacintoshSetUp ) ( which are provided with the Linker utility. ) END
The linker computes the ‘below A5’ size from the variables defined after the VAR statement, adding space for the Forth stacks, Quickdraw globals and various other things. The offset of the MAIN entry point into the code segment is calculated and the jump table set up. MakeJumpTable and MakeMain are the words that create the jump table and code segment 1.
MachSetUp initializes the registers for Mach2 usage. Floating point (D7), parameter (A6) and return (A3) stacks are created above the current stack base in the application globals area. The A7 stack, starting at CurStackBase, remains unaffected. The application globals area is then cleared.
MacintoshSetUp does the standard initialization calls to _MoreMasters, _InitGraf, _InitFonts, _InitWindows, _InitMenus, _TEInit, _InitDialogs, _FlushEvents and _InitCursor.
After these initialization calls, the main program may be entered. An example of a short program which creates a window and beeps is given in the listing. This program, too, is only 858 bytes long (!!!).
Mach 2.14 upgrade
For those of you who haven’t yet upgraded to Mach2.14, I’ll briefly review the latest changes.
1. CASE optimization: redundant instruction sequences of the type
MOVE.L D0,-(A6) MOVE.L (A6)+,D0
are no longer generated.
2. Local variable handling: the new release offers access to the local variable compiler with the words LALLOT and LP@. For example, a word might define a local 16-byte buffer in the following way:
: EXAMPLE { | [ 12 LALLOT ] myBuffer -- } CR .” Please enter your name “ ^ myBuffer 16 EXPECT CR .” Hello “ ^ myBuffer SPAN @ TYPE ;
The local variable compiler can be further enhanced through ‘local variable compiling words’; examples on how to do this are given on the 2.14 release disk.
3. Disassembler: References to USER and global variables are now given with their Forth names. Disassembly speed has been greatly improved, which is particularly evident when executing IL on a Mac Plus or SE. 68881 opcodes are now supported, however, 68020-specific instructions not yet.
4. New words: ASCII now takes up to four characters, for easy definition of resource types. 4+, 4-, 4*, 4/ have been added. a n SHIFT will shift a 32-bit word a by n bits.
5. The trap list has been updated.
Feedback dept.
“Dear Jörg,
I saw a discussion of accented character problems in the July MacTutor and thought I would throw in a few digressions on that matter.
First, you and your readers might be interested to know that Apple has removed the scaron and zcaron characters from the new NTX PROMs against the recommendation of Adobe. These characters were not accessible from the keyboard, because they are uncoded, meaning that no ASCII value is assigned. The only way to access them is via Postscript character names. The good news is that several new characters were added making the NTX almost compliant with the ISO 8859 character set that Adobe routinely supplies with all new fonts. (Apple removed the ´y and ´Y, too).
For those of you who want to see the unencoded characters, you can get at them with the following Postscript code and a download utility, if you have one of the new unprotected Adobe fonts or a late model Laserwriter Plus with v.3 PROMs:
/Garamond-Light findfont dup length dict /newdict exch def {1 index /FID ne{ newdict 3 1 roll put }{ pop pop }ifelse } forall /Encoding 256 array def Encoding 0 /Garamond-Light findfont /Encoding get 0 256 getinterval putinterval Encoding 127 /DEL put Encoding 129 /lslash put Encoding 130 /Lslash put Encoding 131 /eth put Encoding 132 /Eth put Encoding 133 /thorn put Encoding 134 /Thorn put Encoding 135 /onehalf put Encoding 136 /onequarter put Encoding 137 /threequarters put Encoding 138 /brokenbar put Encoding 139 /onesuperior put Encoding 140 /twosuperior put Encoding 141 /threesuperior put Encoding 142 /scaron put Encoding 143 /Scaron put Encoding 144 /zcaron put Encoding 145 /Zcaron put Encoding 146 /yacute put Encoding 147 /Yacute put newdict /Encoding Encoding put /IsoGaramond newdict definefont pop /IsoGaramond findfont 18 scalefont setfont 75 250 moveto (ÄÅÇÉÑÖÜáàâäãåçéèêëíì Garamond) show showpage
Unfortunately there is no way, at present, to get at these with templates in Fontographer, so you have to make your own composites, if you want to add these characters to PostScript fonts.
Best regards, Tim Ryan
SourceNet
P.O.Box 6767
Santa Barbara, CA 93160
PS: The standalone caron () is frequently found as ASCII character 255, one of the last four untypeable characters. It can be accessed using QUED, ... and MS Word if you enter the character using its ASCII value.
By the way, I did get a Greek + Hebrew System from Apple-France via persistent phone calls.
I’ve enclosed the first draft of an article that will appear in my forthcoming book “The Macintosh Book of Fonts”. If you’re interested in reprinting the final draft when it’s available, let me know.
Tim “
Thanks, Tim, for that interesting letter (I’ve enclosed your Postscript code on the source code disk). Now if all these characters were defined somewhere in the standard fonts, wouldn’t that be nice? I always wondered why there were so many empty places in the font definition tables, seems like a waste of space to me
In the next issue we’ll introduce - with other contributions from this side of the Atlantic - a very nice and powerful utility for changing keyboard definitions, so at least that problem can be overcome. Till then.
Listing 1: Mach 2.14 single-segment linker \ © Waymen Askey c/o Palo Alto Shipping \ Reprinted with permission. -- JL \ Guidelines for use of the single-segment “linker.” \ This utility is NOT meant to replace the \ standard Mach TURNKEY process. Its use (at present) \ is limited to creating small (one-segment, less than \ 32K) programs which do NOT require the multi-tasking, \ I/O, and auto event-handling support which the normal \ turnkey process supplies. \ Also, since this utility is being supplied free to \ Mach users, Palo Alto Shipping will NOT assume \ responsibility for support of the utility, nor \ will we be held responsible for any errors (bugs) \ which it may produce. \ It should, however, point the way for other \ compiler enhancements by users. The “bottom line” is \ that Mach can be used to create any type (and size) of \ Macintosh application, DA, driver, INIT, etc. \ Waymen @ PASC ( \ The following words MAY be used freely within the \ stand-alone, “linked” application. \ ! “ + +! ^ +> - -> 0< 0= 0> 1+ 1- 2* 2+ 2- 2/ 2DROP 2DUP 2OVER < <> = > >BODY >R ?DUP @ ABS AND ASCII C! C@ DROP DUP EXIT I I’ J LEAVE L_EXT NEGATE NOT OR OVER PAD PICK R> R@ SWAP U< W! W@ XOR { (it’s OK to use local variables) \ The following control and branching structures MAY \ also be used. \ IF ELSE THEN BEGIN WHILE REPEAT UNTIL AGAIN CASE ENDCASE OF ENDOF DO LOOP +LOOP \ All assembler words may be used. \ The following compilation words MAY be used to \ create your application (but don’t attempt to \ compile them, they can’t be executed during the \ run-time of your finished application). \ : ; VARIABLE CONSTANT USER CREATE DOES> ;CODE CODE END-CODE ALLOT VALLOT , W, C, HERE COMPILE [COMPILE] IMMEDIATE SMUDGE LITERAL LAST MACH RECURSIVE [ ] \ Note, global variables may ONLY be used if you \ declare a VAR block. \ [‘] should be used with caution. \ Don’t use it on words defined outside of your \ program block. \ If you wish to use EXECUTE, it may be redefined as \ CODE EXECUTE ( a -- ) MOVE.L (A6)+,A0 JSR (A0) RTS END-CODE MACH \ ONLY the following MAC vocabulary words MAY be used. \ Remember to use (CALL) instead of CALL. \ (CALL) All CONSTANTS used for the creation of user interface structures (CLOSEBOX, VISIBLE, etc.) If you define a VAR block, EVENT-RECORD (and all other system global variables) may be used as a storage area only -- events (and other information) will NOT automatically be posted there). \ These utilities may also be used. TRAP# TRAPLIST TRAPNAME \ ==================================== \ ========== Can’t Use These ============ \ Words which may NOT be used!!! This is NOT a \ complete list, just some of the more common words. \ You must NOT compile any word which is referenced \ through Mach’s own jump table (words which compile \ a JSR d(A5) instruction. \ CALL GLOBAL TERMINAL TURNKEY NEW.WINDOW ADD (etc.) BUILD TASK TASK-> BYE EVENT-TABLE PAUSE All I/O such as KEY EXPECT EMIT .” TYPE (etc.) <# # #S #> DEPTH 2SWAP CMOVE * / /MOD */MOD */ (if you are using a Mac II exclusively, you may substitute the new 32-bit math routines which came with the last Mach upgrades.) NO SANE words, NO TALKing words, NO I/O words. None of the “high-level” FILE words in the MAC vocabulary. NO words which reference the multi-tasking kernel, NO I/O task words (i.e. events MUST be handled explicitly, you must create your own event-loop). A space for USER variables is reserved for your program, but all of them (except for the TIB value, S0, and RETURN_STK) are initialized to zero. Consider USER variables as just another global storage area. Words like BASE and (ABORT) may be used; however, they will have NO effect on your program unless you specifically design the words to use them. ) \ ---------------------------------------------------------------------- \ A simple, one-segment linker which may \ be used (with restrictions) to create \ small applications in high-level Forth. \ Also allows you to create very small assembly \ language programs (mininum size about 40 bytes) \ With slight modifications to the “linker” and the \ proper SetUp word, could also be used \ to create DA’s, FKEY’s, XCMD’s, and INIT’s. \ -- Waymen \ @ Palo Alto Shipping Company ONLY MAC ALSO FORTH DEFINITIONS DECIMAL $908 CONSTANT CurStackBase $434F4445 CONSTANT ‘CODE’ $4150504C CONSTANT ‘APPL’ $3F3F3F3F CONSTANT ‘????’ %1 CONSTANT MainErr %10CONSTANT EndErr %100 CONSTANT ProcErr $12344320 CONSTANT GoodStart $1234432F CONSTANT StartFlag $12344328 CONSTANT GoodEnd \ The default stack and USER variable sizes \ to be used in building the jump table. \ I’ve made the USER size larger to allow \ for a 256 byte PAD 572CONSTANT USERSize ( USER variables) 74 CONSTANT TIBSize( plus STATUS) 600CONSTANT ParameterSize ( A6 & A3 stacks) 200CONSTANT FPSize ( FP stack) 206CONSTANT GrafSize ( QD globals) $20CONSTANT BL -1 CONSTANT TRUE 0CONSTANT FALSE VARIABLE VarEntry VARIABLE SegmentEntry VARIABLE MainEntry VARIABLE SegmentEnd VARIABLE ProgramFlag VARIABLE ProgramName 28 VALLOT VARIABLE JumpTable 20 VALLOT : -Leading { addr cnt | whiteSpace -- addr’ cnt’ } \ Adjusts addr and cnt to “strip” leading spaces from a string. \ Addr is the starting character address, \ cnt is the original length. 0 -> whiteSpace BEGIN addr whiteSpace + C@ BL = whiteSpace cnt < AND WHILE 1 +> whiteSpace REPEAT addr whiteSpace + cnt whiteSpace - ; : RemoveSpaces { addr | cnt -- } \ Given counted string at addr, remove trailing and leading \ spaces and repack string. addr COUNT -TRAILING addr C! DROP addr COUNT -Leading -> cnt ( addr’) addr 1+ cnt CMOVE cnt addr C! ; : Scan { addr num delimiter | cnt char -- flag } \ Scans input stream, placing characters into string at addr until \ num characters are received or delimiter is found. \ If delimiter is NOT found prior to num, return FALSE \ else return TRUE. num 0> IF 0 -> cnt BEGIN 0 WORD 1+ C@ -> char char delimiter = NOT num cnt > AND WHILE 1 +> cnt char addr cnt + C! REPEAT cnt addr C! char delimiter = ELSE 0 addr ! FALSE THEN ; : PROGRAM { | cnt scanFlag -- } \ Gets program name and init’s linker variables. ProgramName 31 ASCII ; Scan -> ScanFlag ProgramName RemoveSpaces ProgramName C@ 0= scanFlag 0= OR ABORT” Must use ; to delimit program name!” 0 MainEntry ! 0 SegmentEnd ! 0 VarEntry ! StartFlag ProgramFlag ! ; : ClearErr ( errNum -- ) ProgramFlag @ XOR ProgramFlag ! ; : VAR ( -- ) \ Ensure that current VP offset from A5 is \ even, then save it. VP @ 1 AND IF 1 VALLOT THEN VP @ ABS VarEntry ! ; : Globals? ( -- ) \ Checks to see if a VAR statement was made. VarEntry @ 0= IF 10 CALL SysBeep CR .” WARNING: No global variables were declared!” THEN ; : ?HERE ( -- a ) \ Ensures that HERE pointer is even, then \ returns HERE. HERE 1 AND IF 1 ALLOT THEN HERE ; : PROCEDURES ( -- ) ProcErr ClearErr ?HERE SegmentEntry ! 4 ALLOT ; : MAIN ( -- ) MainErr ClearErr ?HERE MainEntry ! ; : END ( -- ) EndErr ClearErr ?HERE SegmentEnd ! ; : ZeroFlags ( -- ) 0 ProgramFlag ! 0 VarEntry ! 0 MainEntry ! 0 SegmentEnd ! ; : BelowA5 ( -- n ) \ Calculates the Below A5 space for \ the jump table. VarEntry @ DUP 0= IF DROP GrafSize THEN USERSize + TIBSize + ParameterSize + FPSize + ; : MakeJumpTable ( -- handle f ) \ handle is to a generic, one-entry jump table. $00000028JumpTable! \ Above A5 size BelowA5JumpTable 4 +! \ Global variable space $00000008JumpTable 8 + ! \ Jump table length $00000020JumpTable 12 + ! \ Jump table A5 offset \ Calculate segment entry point MainEntry @ SegmentEntry @ 4 + - ( entry) JumpTable 16 + W! $3F3C0001JumpTable 18 + ! \ MOVE.W #1,-(A7) $0001A9F0JumpTable 22 + W! \ _LoadSeg JumpTable 24 CALL PtrToHand ; : MakeMain ( -- handle f ) \ Offset to first jump-table entry 0 SegmentEntry @ W! \ Only one jump-table entry 1 SegmentEntry @ 2+ W! SegmentEntry @ ( start of segment ) SegmentEnd @ SegmentEntry @ - ( length of segment ) CALL PtrToHand ; : Link { refNum | JumpHandle MainHandle -- } \ Creates, then adds CODE segments 0 and 1 \ to file refNum refNum IF MakeJumpTable IF ZeroFlags refNum CALL CloseResFile CR .” MakeJumpTable error!” ABORT THEN -> JumpHandle JumpHandle ‘CODE’ 0 “ Jump Table” CALL AddResource CALL ResError IF ZeroFlags refNum CALL CloseResFile JumpHandle CALL DisposHandle DROP CR .” Link (0): AddResource error!” ABORT THEN MakeMain IF ZeroFlags refNum CALL CloseResFile JumpHandle CALL DisposHandle DROP CR .” MakeMain error!” ABORT THEN -> MainHandle MainHandle ‘CODE’ 1 “ Main” CALL AddResource CALL ResError IF ZeroFlags refNum CALL CloseResFile JumpHandle CALL DisposHandle DROP MainHandle CALL DisposHandle DROP CR .” Link (1): AddResource error!” ABORT THEN THEN ; : CreateApplFile { | refNum -- refNum or zero } \ Remember to delete previously made files! 0 -> refNum ‘????’ ‘APPL’ ProgramName 0 CreateFile DISK 4 + W@ 0= IF ProgramName CALL CreateResFile ProgramName CALL OpenResFile \ This logic returns either a valid refNum or zero, \ as OpenResFile returns a -1 if it can’t open the file. DUP -1 = NOT AND -> refNum THEN refNum ; : ?Error { errFlag -- } \ Checks for proper program headings errFlag GoodEnd XOR IF CR .” Missing: “ errFlag $FFFFFFF0 AND GoodStart = IF errFlag %111 AND CASE MainErr OF.” MAIN “ ENDOF EndErr OF .” END “ ENDOF ProcErr OF.” PROCEDURES “ ENDOF ( else) .” MAIN, END and/or PROCEDURES “ ENDCASE ELSE .” PROGRAM “ THEN .” Statement(s)!” ZeroFlags ABORT THEN ; : MakeApplication { | refNum -- } ProgramFlag @ ?Error CreateApplFile -> refNum refNum IF refNum Link Globals? refNum CALL CLoseResFile ZeroFlags ELSE CR .” CreateFile error #” DISK 4 + W@ L_EXT . ZeroFlags ABORT THEN ; \ ============================================ \ All of the code previous to here will NOT be included \ in the linked program. Thus, the above utilities may be \ workspaced, used and/or enhanced at will. \ MachSetUp and MacintoshSetUp should appear as the \ first statements in your MAIN or LAUNCH word. CODE MachSetUp ( -- ) \ Sets up stacks for high-level Forth. \ Not needed if you work only in assembly language. MOVE.L CurStackBase,D0 MOVE.L D0,D1 ADD.L #FPSize,D0 MOVE.L D0,D7 \ FP stack MOVEA.L D0,A3 \ “loop” stack ADD.L #ParameterSize,D0 MOVEA.L D0,A6 \ parameter stack ADD.L #TIBSize,D0 MOVEA.L D0,A4 \ USER variables MOVEA.L D1,A0 MOVE.L A5,D0 SUB.L D1,D0\ below A5 bytes to clear DIVU.W #16,D0 MOVE.W D0,D2 \ “blocks” to clear SWAP.W D0\ bytes to clear \ Init all globals, USER \ vars and stack area to zeros BRA.S @20 @10CLR.L (A0)+ CLR.L (A0)+ CLR.L (A0)+ CLR.L (A0)+ @20DBF D2,@10 BRA.S @40 @30CLR.B (A0)+ @40DBF D0,@30 \ Although it can’t really be used, \ here I set-up the (TIB) USER var MOVE.L A6,24(A4) MOVE.L A6,4(A4) \ S0 USER var MOVE.L A3,12(A4)\ RETURN_STK USER var RTS END-CODE MACH CODE MacintoshSetUp ( -- ) _MoreMasters _MoreMasters PEA -4(A5) _InitGraf _InitFonts _InitWindows _InitMenus _TEInit CLR.L -(A7) _InitDialogs MOVE.L #$0000FFFF,D0 _FlushEvents _InitCursor RTS END-CODE MACH \ ============================================= \ ============= An Example ===================== \ From this point on (between the PROCEDURES and END \ statement) is where you place your application code. PROGRAM My Example; \ The required and beginning statement in your program. \ The application will be titled as whatever appears \ between the PROGRAM statement and the delimiting \ colon (up to 31 characters). \ Words defined here \ will NOT be included in your application \ The redefintion of CALL is just a reminder. : CALL CR .” Don’t use CALL here, use (CALL) instead.” ABORT ; 0 CONSTANT NIL -1 CONSTANT InFront 10 CONSTANT TenTicks 30 CONSTANT HalfSecond VAR \ All global variables used within the program MUST follow \ the VAR statement. If you don’t include the VAR \ statement, a warning will be given during program link. \ If you don’t use global variables (or Mach system \ globals), you may ignore the warning. VARIABLE DelayTicks VARIABLE BoundsRect 4 VALLOT PROCEDURES \ All subroutines must appear between PROCEDURES and \ MAIN. Only that code appearing between the \ PROCEDURES and END statements will appear in your \ finished application. : SetDelay ( n -- ) DelayTicks ! ; : Beeper { beepTime -- } HalfSecond TenTicks DO beepTime (CALL) SysBeep I SetDelay DelayTicks @ (CALL) Delay DROP TenTicks +LOOP ; : MakeWindow ( -- a | returns a window pointer) BoundsRect 20 72 492 322 (CALL) SetRect NIL BoundsRect “ Beeper Window” VISIBLE NOGROW InFront NOCLOSEBOX NIL (CALL) NewWindow ; : ProgramLoop { | windowPointer -- } NIL -> windowPointer MakeWindow -> windowPointer 10 Beeper windowPointer 0= NOT IF 10 (CALL) SysBeep windowPointer “ BYE” (CALL) SetWTitle 60 (CALL) Delay DROP windowPointer (CALL) DisposWindow THEN ; MAIN \ The program’s entry point must appear immediately \ after MAIN : LAUNCH ( -- ) \ Don’t attempt to use local variables in the \ LAUNCH word. The stacks aren’t created until \ after MachSetUp. MachSetUp MacintoshSetUp ProgramLoop ; END ( of program “My Example”) \ This statement does error checking \ and creates the application. MakeApplication CR .( An application called “My Example” has been created.)
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