1 <!doctype linuxdoc system>
5 <!-- Title information -->
8 <author>Maciej Witkowiak, <htmlurl url="mailto:ytm@elysium.pl" name="ytm@elysium.pl">
9 <date>v1.5, 26.12.1999, 2000, 2001, 2002, 2003
11 This is the documentation of cc65's GEOSLib, but information contained here may be also
12 useful for writting GEOS applications in general.
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 As we all know that the best computers in the world are c64 and c128. They have their GUI too -
23 excellent GEOS. GEOS seems very difficult and cryptic for many people, from programmer's point
24 of view. That's not true. The designers of GEOS created flexible and powerful system, which
25 is easy to use and program.
27 Coding GEOS in C? That's something new. It is possible now - with Ulrich von Bassewitz's cc65
28 package and my GEOSLib you are able to create GEOS applications in no-time.
30 GEOSLib supports a subset of standard cc65 libraries. Whenever possible native Kernal functions
31 are used (e.g. <tt/memset/ is an alias for <tt/FillRam/), however not all are supported. E.g.
32 string functions like <tt/strcmp/, <tt/strcpy/ are doubled with native <tt/CmpString/,
33 <tt/CopyString/ because the latter can handle only 256 byte strings. Keep this in mind when
34 you will write your program. If you don't need long strings simply use functions from Kernal,
35 resulting code will be smaller.
37 <tt/dio/ - direct disk access is available, but you might have problems with devices other
38 than 1541, 1571 or 1581. RAM drives emulating these should work.
40 <tt/conio/ - simple console input-output is available for command line applications.
41 This implementation assumes that one character will fit in 8x8 cell, so output with
42 default BSW font, which is has 9 points, might be a bit messy.
43 <tt/cputs/ will output characters with fixed width, for proportional spacing use
44 <tt/cpputs/ but this function does not update cursor. There is no color support in
45 GEOS 2.0 so color functions are disabled. Both 40 and 80 columns modes are supported
46 and automatically detected.
48 <tt/tgi/ - TGI driver for GEOS that supports both 40 and 80 columns modes but mode can not be
49 changed between <tt/tgi_init/ and <tt/tgi_done/.
51 <tt/joy/ - JOY driver for GEOS supports only joystick, not current pointing device.
53 It is safe to use these standard includes and their contents:
54 <tt/assert.h, conio.h, dio.h, errno.h, em.h, geos.h, joystick.h, modload.h, mouse.h, stdlib.h, string.h, tgi.h, time.h/
56 It was not tested enough, but functions from these includes might work under GEOS:
59 Functions from the headers above are either standard C library functions or cc65-specific, in
60 either case they are not GEOS specific and so they are not described here.
62 I am an assembler programmer and GEOSLib was designed in such way that cc65 could emit the best
63 available code (well, the best as for machine :). Many of the <tt/void foo (void)/ functions are
64 just raw calls to Kernal (assembled just as <tt/jsr _foo/), look in <tt/gsym.h/, where you
65 will find many definitions of standard GEOS locations. Access to these addresses is optimized by
66 cc65 to simple <tt/lda/ and <tt/sta/. Don't be afraid to use C syntax.
70 You will not need c64 or c128 for development. The only hardware requirement is a PC capable of
71 runing cc65. You will however need c64 or c128 emulator and GEOS image disks (.d64) to test your
76 <item><em/cc65/ Excellent package containing C crosscompiler, crossassembler and linker, you
77 can get it from: <htmlurl url="http://www.von-bassewitz.de/uz/cc65/"
78 name="http://www.von-bassewitz.de/uz/cc65/">
79 <item><em/VICE/ This is portable C64, C128 and few other Commodore computers emulator, you
80 can obtain it from: <htmlurl url="http://www.cs.cmu.edu/~dsladic/vice/vice.html"
81 name="http://www.cs.cmu.edu/~dsladic/vice/vice.html">. VICE package contains
82 c1541 program that is able to convert/unconvert GEOS files to disk images.
83 <item><em/Star Commander/ This tool is only for DOS. You will need it for transferring
84 object files from PC to 1541. There's also one important ability of this
85 tool - it automatically un-converts .cvt files into GEOS native format on
87 <item><em/cbm4linux/ A Linux kernel module that allows for communication with 1541 and
88 other Commodore IEC bus drives. It can be replacement for Star Commander if
89 you want only to transfer files to a disk and uncovert using GEOS program for
90 this purpose. Check out: <htmlurl url="http://www.lb.shuttle.de/puffin/cbm4linux/"
91 name="http://www.lb.shuttle.de/puffin/cbm4linux">
94 VICE and cc65 are portable - they run on variety of platforms - DOS, Win32 and UNIX. GEOSLib only
97 <em/Update:/ starting from v2.5.0 GEOSLib is a part of cc65 package as its GEOS support library.
101 I want to thank Uz for his cc65 package, Alexander Boyce for his excellent GEOS Programmer's
102 Reference Guide and BSW for GEOS.
104 GEOSLib is covered by the same license as cc65. You can find the whole text among documentation.
105 I would really appreciate if you would like to send me your comments, suggestions, questions,
106 changes, bug reports etc. I will also appreciate if you will just give me a sign that you are
107 using GEOSLib - not especially something big and important, mail me even if you are just playing
110 You can send postcards with hellos to:
112 Maciej Witkowiak, ul. Slowackiego 6/57, 77-400 ZLOTOW
116 e-mail: <tt/ytm@elysium.pl/
118 <sect>What have you got and what to do with it?
120 This chapter describes some rules you ought to obey, and how to use GEOSLib.
124 Apart from this file, which merely describes only standard GEOS library functions, you should read
125 <tt/grc/ (GEOS resource compiler) documentation. There are informations about necessary resource
126 files (each GEOS application neeeds at least one) and the building process - what should be done
127 and in what order. Please also read cc65's documentation on how to compile C, assembler and link
130 All in all, you just need to place
132 #include <geos.h>
134 on top of your source.
136 As a general rule read the sources of example programs and read the headers. These are the most
137 reliable sources of knowledge ;). You will also find there many C macros representing various
138 arguments passed to functions. Please use them. You will find your sources easier to understand,
139 and it will be easier to find bugs.
141 All types used in GEOSLib are <tt/unsigned/.
143 Screen coordinates are given in pixels unless stated differently.
145 <sect1>Notes on style
147 Contrary to typical GEOS assembly program which has a main function called after loading that
148 setups the screen, menus, icons etc. exiting from <tt/main/ function in C is equivalent to
149 calling <tt/exit()/. These two are the only safe methods of terminating applications. DO NOT
150 USE <tt/EnterDeskTop/! Your data may be lost as library destructors and functions registered
151 with <tt/atexit/ will not be called.
153 For GEOS GUI applications the recommended program structure is to have everything initialized
154 in <tt/main/ function and at the end of it a call to <tt/MainLoop()/ function. WARNING! This
155 function never returns, any code between <tt/MainLoop();/ and the end of <tt/main/ will not
156 be executed. You have to call <tt/exit()/ explicitly somewhere in your code (e.g. in a menu
157 handler or via DialogBox action).
159 Whenever possible use definitions from <tt/gsym.h/. The resulting code is translated by cc65 into
160 series of <tt/lda/ and <tt/sta/, so you can't do it better :-).
162 Don't hesitate to use library functions. Everything was written with size and speed in mind. In
163 fact many calls are just redirections to GEOS kernal which results in simple <tt/jsr/.
165 The <tt/main/ function receives the standard <tt/argc/ and <tt/argv/ parameters. There are
166 always either 1 or 3 parameters. DOS application name is always set as <tt/argv[0]/.
167 If present, <tt/argv[1]/ and <tt/argv[2]/ will be set to data filename and data diskname (it only
168 works if user double-clicks on data file associated with your application). Note that it is up
169 to your application to determine which of the available (up to four) disk drives has the disk
170 with given diskname inside. If this fails your program should ask to insert the proper disk into
171 one of available drives.
173 You might wonder why I have chosen sometimes weird order of arguments in functions. I just
174 wanted to avoid unnecessary pushing and popping arguments from stack because cc65 can pass single
175 <tt/unsigned int/ through CPU registers.
177 Do not try to compile in strict ANSI mode. Library uses cc65 extensions which are not available in
180 It is possible to use dynamicaly loaded modules, three such modules are provided:
181 GEOS TGI driver, GEOS EMD driver (for VDC extended memory) and GEOS JOY driver.
182 Just make sure that their filenames appear UPPERCASE in DeskTop. There are no more special
183 recommendations, read cc65 documentation about modules and demo programs source code.
185 <sect>Library Functions
187 Functions here are sorted more or less in the way they appear in header files. This way I am able
188 to keep functions covering similar task near each other. All function names are identical to those
189 from <tt/geosSym/ file provided with GeoProgrammer package. Only my extensions to <tt/geosSym/
190 are covered by new names, but I tried to keep them in the naming convention.
194 This section covers drawing package of GEOS along with text output routines.
198 <tt/void SetPattern (char pattern)/
200 This function sets current pattern to given. There are 32 different patterns in GEOS. You can
201 see them together in the filling box in GeoPaint.
203 <sect2>GraphicsString
205 <tt/void GraphicsString (char *myGString)/
207 One of the more powerfull routines of GEOS. This function calls other graphic functions depending
208 on given command string. See structures chapter for more detailed description of the structure of it.
210 <sect2>Rectangle functions
212 Parameters to those functions are grouped in <tt/struct window drawWindow/. To speed up things and
213 reduce overhead this structure is glued to zero page locations, where all rectangle functions
214 expect their parameters. You can modify data directly (e.g. <tt/drawWindow.top=10/) or via
215 <tt/InitDrawWindow/ function. Contents of <tt/drawWindow/ are guaranteed not to change only when
216 using graphics functions. In other case you should keep your data in separate <tt/struct window/
217 and use <tt/InitDrawWindow/ before first call to rectangle functions.
219 <sect3>InitDrawWindow
221 <tt/void InitDrawWindow (struct window *myWindow)/
223 This function only copies contents of <tt/myWindow/ into system area of <tt/drawWindow/. Use it
224 if for some reason you have to keep window data out of zero page space.
228 <tt/void Rectangle (void)/
230 This draws on screen rectangle filled with current pattern.
232 <sect3>FrameRectangle
234 <tt/void FrameRectangle (char pattern)/
236 This one draws frame with given bit pattern (not a pattern from GEOS palette).
238 <sect3>InvertRectangle
240 <tt/void InvertRectangle (void)/
242 Just as the name says...
244 <sect3>ImprintRectangle and RecoverRectangle
246 <tt/void ImprintRectangle (void)/
248 <tt/void RecoverRectangle (void)/
250 These two functions are for copying parts of the screen to (<tt/Imprint/) and from (<tt/Recover/)
251 backbuffer of the screen. For example when drawing new menu box GEOS first uses
252 <tt/ImprintRectangle/ to save the area under the box, and restores it by <tt/RecoverRectangle/ upon
255 <sect2>Line Functions
257 GEOS drawing package is optimized so there are different functions for drawing vertical and
260 <sect3>HorizontalLine
262 <tt/void HorizontalLine (char pattern, char y, unsigned xStart, unsigned xEnd)/
264 This function draws horizontal line using given pattern - here it is a true bit pattern, not
265 pattern set by <tt/SetPattern/.
269 <tt/void InvertLine (char y, unsigned xStart, unsigned xEnd)/
271 There is only horizontal version.
275 <tt/void RecoverLine (char y, unsigned xStart, unsigned xEnd)/
277 This function recovers only one line. It is utilized by <tt/RecoverRectangle/. See its description
282 <tt/void VerticalLine (char pattern, char yStart, char yEnd, unsigned x)/
284 This function draws vertical line using given pattern. Note that <tt/pattern/ is not a pattern
285 number as set in <tt/SetPattern/ but a true bit pattern.
289 <tt/void DrawLine (char mode, struct window *myWindow)/
291 <tt/top/ parameters of <tt/struct window/ describe the starting point of the line, while
292 <tt/bottom/ are for the ending point. If <tt/mode/ is <tt/DRAW_DRAW/ then current pattern from
293 <tt/SetPattern/ is used for drawing. If <tt/mode/ is <tt/DRAW_ERASE/ then line is erased from the
294 screen. If <tt/mode/ is <tt/DRAW_COPY/ then line is copied from/to back/frontbuffer, according to
295 <tt/dispBufferOn/ setting.
297 <sect2>Point Functions
299 Parameters to these two functions are passed by a pointer to own <tt/struct pixel/ filled with
304 <tt/void DrawPoint (char mode, struct pixel *myPixel)/
306 Depending on <tt/mode/ (see <tt/DrawLine/) draws/erases/copies a single point
311 <tt/char TestPoint (struct pixel *myPixel)/
313 This function tests if given pixel is set and returns <tt/true/ (non-zero) or <tt/false/ (zero).
315 <sect2>Character and string output
319 <tt/cpputsxy (char x, char y, char *myString)/
321 <tt/cpputs (char *myString)/
323 Actually this is a part of <tt/conio/, but this function is non-standard. It is
324 a variety of <tt/cputs/ that will output string with proportional spacing, not
325 fixed like <tt/cputs/.
329 <tt/void PutChar (char character, char y, unsigned x)/
331 This function outputs single character using current style and font to screen.
335 <tt/void PutString (char *myString, char y, unsigned x)/
337 Same as <tt/PutChar/ except the fact that you can output whole <tt/NULL/-terminated string.
338 See <tt/ggraph.h/ for list of tokens that you can also place in the string - like <tt/CBOLDON/ or
343 <tt/void PutDecimal (char parameter, int value, char y, unsigned x)/
345 This function converts <tt/value/ to its decimal representation and outputs it to the screen.
346 Depending on given <tt/parameter/ the string can be filled with zeroes (string always 5 characters
347 long) or not, to be left or right justified to given pixel. See <tt/ggraph.h/ for predefined
348 values for <tt/parameter/.
354 <tt/char GetCharWidth (char character)/
356 This function returns real width (in pixels) of given character with current font. It can be used
357 for counting the length of string on screen, allowing for indentation or justification.
361 <tt/void LoadCharSet (struct fontdesc *myFont)/
363 This function forces GEOS to use given font instead of own. <tt/myFont/ should be casted from
364 pointer to the start of area where was loaded record from font file (VLIR structure).
368 <tt/void UseSystemFont (void)/
370 This function forces GEOS to use built-in BSW font.
372 <sect2>Bitmap handling
374 I'm not quite sure how are these functions working (except <tt/BitmapUp/) so you should
375 probably look into library sources and compare it with your knowledge. Please let me know
376 if something is wrong or broken.
380 <tt/void BitmapUp (struct iconpic *myPic)/
382 This function unpacks the bitmap and places it on the screen - just as you set it in the
383 <tt/struct iconpic/ pointer to which you pass. See <tt/gstruct.h/ for description of this
384 structure. Note that you can only use packed GEOS bitmaps - simple Photo Scrap is in this format.
388 <tt/void BitmapClip (char skipLeft, char skipRight, unsigned skipTop, struct iconpic *myPic)/
390 This function acts similar to <tt/BitmapUp/ but you can also define which parts of the bitmap are
391 to be drawn - you give the number of columns (8-pixel) to skip on the right and left of the bitmap,
392 and the number of rows to skip from the top if it.
396 <tt/void BitOtherClip (void *proc1, void *proc2, char skipLeft, char skip Right, unsigned skipTop,
397 struct iconpic *myPic)/
399 Similar to the previous one with some extension. <tt/proc1/ is called before reading a byte (it
400 returns in .A next value), and <tt/proc2/ is called every time the parser reads a byte which is
401 not a piece of pattern (byte of code greater than 219). Both procedures should be written
402 separately in assembler and declared as <tt/__fastcall__/ returning char.
404 <sect1>Menus and Icons
406 Here you will find information about functions related with menus and icons.
410 Menus are essencial for GUI. GEOS can handle only one menu at a time, but each menu can call
411 another one, which results in submenu tree. There can be up to 8 menu levels, each one with up
414 Menus are initialized with <tt/DoMenu/ and then Kernal takes care for everything. Your code
415 (called from event handler) should be a function without parameters, returning void. You should
416 use <tt/DoPreviousMenu/ or <tt/GotoFirstMenu/ at least once in its code to have the screen clean.
420 <tt/void DoMenu (struct menu *myMenu)/
422 This function initializes GEOS menu processor and exits. See <tt/DoMenu structure/ for more
423 information about it. Know that many GEOS application just initializes the screen, menu and
424 exits to main Kernal loop, this proves the power of <tt/DoMenu/.
428 <tt/void ReDoMenu (void)/
430 This simply redraws the menu at lowest level. It works like calling <tt/DoMenu/ again with
435 <tt/void RecoverMenu (void)/
437 This function erases current menu from the screen. It doesn't change the menu level.
439 <sect3>RecoverAllMenus
441 <tt/void RecoverAllMenus (void)/
443 This calls <tt/RecoverMenu/ and erases all menus from the screen. Then the menu level is
446 <sect3>DoPreviousMenu
448 <tt/void DoPreviousMenu (void)/
450 This functions causes menu processor to go back one menu level. You should use it in menu
451 handler code to have the screen clean.
455 <tt/void GotoFirstMenu (void)/
457 This one jumps back to the topmost menu. If there is only menu and submenu it works the
458 same as <tt/DoPreviousMenu/.
460 <sect2>Icon Functions
462 Icons are working similar to menus except the fact that there is only one level. Icons are
463 defined as a screen area filled with a bitmap, but if you would setup icons and erase the
464 screen they are still active and clicking in the place where formerly an icon was will cause
465 an effect. Similary if you would setup icons and then turn them off with <tt/ClearMouseMode/
466 the bitmap will be still on the screen but clicking on it would not cause any action.
467 There is only one, but powerful icon function.
471 <tt/void DoIcons (struct icontab *myIconTab)/
473 This function initializes all icons that are present on the screen at once. For more information
474 look at <tt/Icons/ chapter in this manual.
478 This chapter covers the most powerful GEOS user interface function - <tt/DoDlgBox/.
484 <tt/char DoDlgBox (char *dialogString)/
486 DialogBox returns one byte. It can be the value of one of six standard icons (see <tt/gdlgbox.h/)
487 or whatever closing routine passes. Register <tt/r0L/ also contains this value.
489 Read structures chapter for the specs of the <tt/dialogString/.
491 <sect3>RstrFrmDialogue
493 <tt/char RstrFrmDialogue/
495 This function called from within DialogBox event immediately closes the DialogBox and returns
496 the owner ID (or whatever caller has in the .A register).
498 <sect2>GEOSLib extensions
500 To simplify usage of DoDlgBox from C I've wrote some help functions - wrappers for DoDlgBox,
501 with predefined data. In one word - these are standard DialogBoxes you can see in almost every
504 <sect3>DlgBoxYesNo, DlgBoxOkCancel, DlgBoxOk
506 <tt/char DlgBoxYesNo (char *line1, char *line2)/
508 <tt/char DlgBoxOkCancel (char *line1, char *line2)/
510 <tt/void DlgBoxOk (char *line1, char *line2)/
512 These function show two lines of text in standard-sized DialogBox. You can read the code of
513 pressed icon from return value. E.g. for <tt/DlgBoxYesNo/ it can only be <tt/YES/ or <tt/NO/.
514 You can pass an empty string or NULL to get a blank line.
516 <sect3>DlgBoxGetString
518 <tt/char DlgBoxGetString (char *string, char strlen, char *line1, char *line2)/
520 This function prompts user for entering a string of at most <tt/strlen/ characters. It is returned
521 in <tt/string/. The two given lines of text are shown above the input line. Please remember
522 that there is also <tt/CANCEL/ icon in the DialogBox and you should test if user confirmed his
523 input or gave up. The <tt/string/ is also shown so you can place default input there or remember
524 to place <tt/NULL/ at start.
526 <sect3>DlgBoxFileSelect
528 <tt/char DlgBoxFileSelect (char *class, char filetype, char *filename)/
530 This routine is the standard file selector. It can return <tt/OPEN/, <tt/CANCEL/ or disk error
531 on reading the directory or opening the disk.
532 There is also <tt/DISK/ icon shown, but it is handled internally. You pass as input parameters
533 <tt/filetype/ and pointer to string containing the first part of file's class. If this string is
534 empty (<tt/NULL/ at the start), then all files with given filetype will be shown.
536 At present this file selector handles only first 16 files of given type and supports only one
539 <sect1>Mouse, Sprites and Cursors
541 You will find here functions related to sprite and mouse drawing and handling.
543 <sect2>Mouse related functions
545 These cover mouse - as a general pointing device, but expect user to utilize as different devices
546 as digital or analog joystick, mouse, lightpen or koalapad (whatever it is).
548 <sect3>StartMouseMode
550 <tt/void StartMouseMode (void)/
552 This function initializes mouse vectors - <tt/mouseVector/ and <tt/mouseFaultVec/, and then
555 <sect3>ClearMouseMode
557 <tt/void ClearMouseMode (void)/
559 This function disables all mouse actitivies - icons and menus stop to respond to mouse events,
560 but they are not cleared from the screen.
562 <sect3>MouseUp and MouseOff
564 <tt/void MouseUp (void)/
566 <tt/void MouseOff (void)/
568 The first function turns the mouse pointer on. It will appear on next IRQ. The second one does
569 the opposite - it turns off the pointer, but its position is still updated by input driver.
573 <tt/char IsMseInRegion (struct window *myWindow)/
575 This function tests if mouse pointer is actually in given range of screen. See <tt/gsprite.h/ for
576 description of bits in return values - they describe the position in detail.
580 You are free to use any of the eight sprites, but keep in mind that sprite 0 is actually the mouse
581 pointer and sprite 1 can be overwritten when using text prompt. You don't have to worry about
582 40/80 column issues because GEOS128 has pretty good sprite emulator for VDC.
586 <tt/void DrawSprite (char sprite, char *mySprite)/
588 This function initializes the sprite data. <tt/mySprite/ is a 63-byte table with bitmap data, which
589 is copied to system sprite area (at <tt/sprpic/ - see <tt/gsym.h/). Hardware sprite registers are
590 not initialized and sprite is not yet visible.
594 <tt/void PosSprite (char sprite, struct pixel *myPixel)/
596 This function positions the sprite on the screen. Given coordinates are screen ones - they are
597 converted to sprite coordinates by GEOS. Due to this you cannot use this function to position your
598 sprite off the left or top to the screen.
600 <sect3>EnablSprite and DisablSprite
602 <tt/void EnablSprite (char sprite)/
604 <tt/void DisablSprite (char sprite)/
606 These two functions are responsible for making the sprite visible or not.
608 <sect2>Cursors and Console
610 <sect3>InitTextPrompt
612 <tt/void InitTextPrompt (char height)/
614 This function initializes sprite 1 for text prompt with given <tt/height/. This parameter can be in
617 <sect3>PromptOn and PromptOff
619 <tt/void PromptOn (struct pixel *myPixel)/
621 <tt/void PromptOff (void)/
623 The first function places text prompt in given place and enables blinking.
624 The second one is pretty self-explanatory.
628 <tt/char GetNextChar (void)/
630 This function gets next character from the keyboard queue. If the queue is empty it returns
631 <tt/NULL/, otherwise you receive true ASCII code of a character or value of special (function)
632 key. See <tt/gsprite.h/ for list of them.
636 This chapter covers slightly low-level disk routines. You should use them with care, because
637 you may easily corrupt data on disks. Also remember that contemporary GEOS supports many various
638 devices and sticking to 1541 track layout (e.g. expecting the directory on track 18) might be
641 For some purposes you might consider using <tt/dio.h/ interface to disk access. It is native.
643 All GEOS disk functions return error code in X register. In some cases this is returned by
644 GEOSLib function (if its type is <tt/char/), but in all cases last error is saved in <tt/__oserror/
645 location. If it is nonzero - an error occured. See <tt/gdisk.h/ for the list of possible errorcodes.
646 You need to include <tt/errno.h/ to get <tt/__oserror/, together with standard <tt/errno/. The
647 latter gives less verbose, but still usable information and can be used with <tt/strerror/.
648 Probably you will get more information using <tt/_stroserror/ in similar way.
650 For passing parameters use almost always pointer to your data e.g. <tt/ReadBuff (&myTrSe)/.
652 <sect2>Buffer functions
654 These functions are taking single data sector (256 bytes) to read or write on a disk.
656 <sect3>ReadBuff and Writebuff
658 <tt/char ReadBuff (struct tr_se *myTrSe)/
660 <tt/char WriteBuff (struct tr_se *myTrSe)/
662 These functions read and write sector placed at <tt/diskBlkBuf/.
664 <sect3>GetBlock and ReadBlock
666 <tt/char GetBlock (struct tr_se *myTrSe, char *buffer)/
668 <tt/char ReadBlock (struct tr_se *myTrSe, char *buffer)/
670 These two functions are reading a single block directly at 256 byte array placed at <tt/buffer/.
671 The difference between them is that <tt/GetBlock/ will initialize TurboDos in drive if it was not
672 enabled. <tt/ReadBlock/ assumes that it is already enabled thus being slightly faster.
674 <sect3>PutBlock, WriteBlock, VerWriteBlock
676 <tt/char PutBlock (struct tr_se *myTrSe, char *buffer)/
678 <tt/char WriteBlock (struct tr_se *myTrSe, char *buffer)/
680 <tt/char VerWriteBlock (struct tr_se *myTrSe, char *buffer)/
682 Similar to previous but needed for writting the disk. <tt/VerWriteBlock/ verifies the data after
683 writting. In case of error five tries are attempted before error code is returned.
685 <sect2>Directory header
687 Functions described here are operating on <tt/curDirHeader/ where current disk header is stored.
688 On larger capacity drives (than 1541) the second part of directory header in <tt/dir2Head/.
692 <tt/void GetPtrCurDkNm (char *diskName)/
694 This function fills given character string with the name of current disk. It is converted to C
695 standard - string is terminated with <tt/NULL/ character instead of code 160 as in Commodore DOS.
696 Note that passed pointer must point to an array of at least 17 bytes.
698 <sect3>GetDirHead and PutDirHead
700 <tt/char GetDirHead (void)/
702 <tt/char PutDirHead (void)/
704 These functions are reading and writting the directory header. You should use <tt/GetDirHead/ before
705 using any functions described below, and you should use <tt/PutDirHead/ to save the changes on the
706 disk. Otherwise they will be lost. Operating area is the <tt/curDirHead/.
710 <tt/unsigned CalcBlksFree (void)/
712 This function returns the number of free blocks on current disk. It is counted using data in
713 <tt/curDirHead/ so you must initialize the disk before calling it.
717 <tt/char ChkDskGEOS (void)/
719 This functions checks <tt/curDirHead/ for GEOS Format identifier. It returns either true or false,
720 and also sets <tt/isGEOS/ properly. You must initialize the disk before using this.
724 <tt/char SetGEOSDisk (void)/
726 This function initializes disk for use with GEOS. It sets indicator in directory header and
727 allocates a sector for the directory of border files. You don't need to initialize the disk before
732 <tt/char FindBAMBit (struct tr_se *myTrSe)/
734 This function returns the bit value from BAM (Block Allocation Map) for given sector. The bit is
735 set if the sector is free to use. Returned value is always zero if the sector is already allocated.
736 In fact, this function could be used in a following way:
738 #define BlockInUse FindBAMBit
740 if (!BlockInUse(&myTrSe)) {
741 ... block not allocated ...
745 Anyway, I feel that this function is too low-level.
747 <sect3>BlkAlloc and NxtBlkAlloc
749 <tt/char BlkAlloc (struct tr_se output[&rsqb, unsigned length)/
751 <tt/char NxtBlkAlloc (struct tr_se *myTrSe, struct tr_se output[&rsqb, unsigned length)/
753 Both functions are allocating enough disk sectors to fit the number of <tt/length/ in them. You
754 will find output in <tt/output/ which is table of <tt/struct tr_se/. The last entry will have the
755 number of track equal to 0 and sector equal to 255. The simpliest way of using them is to use
756 predefined space in GEOS data space and pass <tt/fileTrScTab/, which is a predefined table.
758 The difference between those two is that <tt/NextBlkAlloc/ will start allocating from given sector,
759 and <tt/BlkAlloc/ starts from the first nonused sector.
761 You need to use <tt/PutDirHead/ later to save any changes in BAM.
765 <tt/char FreeBlock (struct tr_se *myTrSe)/
767 Simply deallocates a block in BAM. You need to update BAM with <tt/PutDirHead/.
771 <tt/struct tr_se SetNextFree (struct tr_se *myTrSe)/
773 This function finds the first free sector starting from given track and sector and allocates it.
774 It might return the same argument if the given block is not allocated. I wanted it to be type
775 clean, but it made usage a bit tricky. To assign a value to own <tt/struct tr_se/ you have to
776 cast both variables to <tt/unsigned/. E.g.
780 (unsigned)myTrSe=(unsigned)SetNextFree(&otherTrSe);
783 In this example <tt/otherTrSe/ can be replaced by <tt/myTrSe/.
785 NOTE that you <em/must/ use casting to have correct values.
787 <sect2>Low-level disk IO
789 Functions described here are more usable in kernal or drivers code, less common in applications,
790 but who knows, maybe someone will need them.
792 <sect3>EnterTurbo, ExitTurbo, PurgeTurbo
794 <tt/void EnterTurbo (void)/
796 <tt/void ExitTurbo (void)/
798 <tt/void PurgeTurbo (void)/
800 These functions are interface to GEOS TurboDos feature which makes slow Commodore drives a bit
801 more usable. <tt/EnterTurbo/ enables TurboDos unless it is already enabled. If not, then you will
802 have to wait a bit to transfer TurboDos code into disk drive RAM. <tt/ExitTurbo/ disables TurboDos.
803 This is useful for sending some DOS commands for drive e.g. for formatting. Note that before any
804 interaction with Kernal in ROM you have to call <tt/InitForIO/. You don't have to worry about speed.
805 <tt/EnterTurbo/ will only enable TurboDos (no code transfer) if TurboDos was disabled with
806 <tt/ExitTurbo/. <tt/PurgeTurbo/ acts different from <tt/ExitTurbo/ - it not only disables TurboDos,
807 but also removes it from drive RAM (not quite true, but it works like that). After using
808 <tt/PurgeTurbo/ the next call to <tt/EnterTurbo/ will reload drive RAM.
810 <sect3>ChangeDiskDevice
812 <tt/char ChangeDiskDevice (char newDevice)/
814 This function changes logical number of current device (in fact drives only) with given one. It is
815 usable for swapping drives. There's no check if given <tt/newDevice/ already exist, so if you want
816 to change the logical number of drive 8 to 9 and you have drive number 9 then GEOS will probably
817 hang on disk access. Use safe, large numbers. Note that safe IEC range is 8-31.
819 <sect2>Disk Initialization
821 GEOS has two functions for initialization ('logging in' as they say on CP\M) the disk.
824 <tt/char OpenDisk (void)/
826 This function initializes everything for a new disk. It loads and enables TurboDos if needed.
827 Then the disk is initialized with <tt/NewDisk/. Next, <tt/GetDirHead/ initializes <tt/curDirHead/.
828 Disk names are compared and if they differ then disk cache on REU is cleared. Finally format is
829 checked with <tt/ChkDkGEOS/ and disk name is updated in internal tables.
833 <tt/char NewDisk (void)/
835 This function is similar to DOS command I. It clears REU cache and enables TurboDos if needed.
839 This section cover GEOS file interface.
841 <sect2>Directory handling
843 Functions described here are common for SEQ and VLIR structures.
845 <sect3>Get1stDirEntry and GetNxtDirEntry
847 <tt/struct filehandle *Get1stDirEntry (void)/
849 <tt/struct filehandle *GetNxtDirEntry (void)/
851 These two functions are best suited for scanning whole directory for particular files. Note that
852 returned filehandles describes all file slots in the directory - even those with deleted files.
853 The return value can be obtained by casting both sides to <tt/unsigned/ - as in <tt/SetNextFree/
854 function or read directly after call to those two functions from <tt/r5/. Current sector number
855 is in <tt/r1/ and sector data itself is in <tt/diskBlkBuf/.
859 <tt/char FindFile (char *fName)/
861 This function scans whole directory for the given filename. It returns either 0 (success) or 5
862 (FILE_NOT_FOUND, defined in <tt/gdisk.h/) or any other fatal disk read error. After successful
863 <tt/FindFile/ you will have <tt/struct filehandle/ at <tt/dirEntryBuf/ filled with file's data and
864 other registers set as described in <tt/GetNxtDirEntry/.
868 <tt/char FindFTypes (char *buffer, char fType, char fMaxNum, char *classTxt)/
870 This function scans directory and fills a table at <tt/buffer/ with <tt/char [17]/ entries.
871 <tt/fType/ is GEOS type of searched files and <tt/classTxt/ is a string for Class field in file
872 header. Class will match if given will be equal or shorter than that found in file's header block.
873 If you want just to find all files with given GEOS type you should pass empty string or <tt/NULL/ as
874 <tt/classTxt/. Be warned that for searching <tt/NON_GEOS/ files must pass <tt/NULL/ as <tt/classTxt/.
875 <tt/fMaxNum/ is the maximal number of found files, thus the <tt/buffer/ must
876 provide area of size equal to <tt/17 * fMaxNum/.
877 This function returns the number of found files, ranging from 0 to number passed as <tt/fMaxNum/.
878 Return value can be also restored from <tt/r7H/.
882 <tt/char DeleteFile (char *fName)/
884 This function deletes a file by its name. It works for SEQ and VLIR files.
888 <tt/char RenameFile (char *oldName, char *newName)/
890 I think it is obvious...
894 <tt/char GetFHdrInfo (struct filehandle *myFile)/
896 This function loads the file header into <tt/fileHeader/ buffer. Using after e.g. <tt/FindFile/
897 you can pass address of <tt/dirEntryBuf/.
899 <sect2>Common and SEQ structure
901 Functions described here are common for SEQ and VLIR structures because arguments passed are
902 starting track and sector which may point either to start of a chain for VLIR or data for SEQ.
906 <tt/char __fastcall__ GetFile(char flag, const char *fname, const char *loadaddr, const char *datadname, const char *datafname)/
908 This routine loads and runs a given file <tt/fname/. The file must be one of following types:
909 <tt/SYSTEM, DESK_ACC, APPLICATION, APPL_DATA, PRINTER,/ or <tt/INPUT_DEVICE/. The execution
910 address is taken from file header. If it is zero, then file is only loaded. Only the first chain
911 from VLIR files is loaded. If <tt/flag/ has bit 0 set then load address is taken from <tt/loadaddr/
912 and not from file header. In this case <tt/APPLICATION/ files will be only loaded, not executed.
913 This does not apply to <tt/DESK_ACC/. If either bit 6 or 7 of <tt/flag/ are set, then 16 bytes from
914 <tt/datadname/ is copied to <tt/dataDiskName/ and 16 bytes from <tt/datafname/ goes to <tt/dataFileName/
915 thus becoming parameters for the new application. Pass <tt/NULL/ as any unused parameter.
920 <tt/char ReadFile (struct tr_se *myTrSe, char *buffer, unsigned fLength)/
922 This function reads at most <tt/fLength/ bytes into <tt/buffer/ from chained sectors starting at
927 <tt/char ReadByte (void)/
929 This function returns next byte from a file. Before the first call to it you must load <tt/r5/
930 with <tt/NULL/, <tt/r4/ with sector buffer address and <tt/r1/ with track and sector of the
931 first block of a file.
932 Remember to not modify <tt/r1/, <tt/r4/ and <tt/r5/. These registers must be preserved between
933 calls to <tt/ReadByte/.
935 Returned value is valid only if there was no error. End of file is marked as <tt/BFR_OVERFLOW/
936 in <tt/__oserror/, this is set when trying to read one byte after the end of file, in this case
937 returned value is invalid.
941 <tt/char SaveFile (char skip, struct fileheader *myHeader)/
943 <tt/SaveFile/ will take care of everything needed to create a GEOS file, no matter VLIR of SEQ
944 structure. All you need to do is to place data in proper place and prepare a header which will
945 contain all information about a file. The <tt/skip/ parameter says how many directory pages you
946 want to skip before searching for a free slot for directory entry. In most cases you will put
949 You have to declare a <tt/struct fileheader/ and fill it with proper values. There is only one
950 difference - the first two bytes which are link to nonexistant next sector are replaced by a
951 pointer to the DOS filename of the file.
953 When saving sequential files two most important fields in <tt/struct fileheader/ are <tt/fileheader.load_address/
954 and <tt/fileheader.end_address/.
958 <tt/char FreeFile (struct tr_se myTable[])/
960 This function deallocates all sectors contained in passed table.
964 <tt/char FollowChain(struct tr_se *myTrSe, char *buffer)/
966 This function fills a <tt/struct tr_se/ table at <tt/buffer/ with sector numbers for chain of
967 sectors starting with <tt/myTrSe/. You can pass such data (<tt/buffer/) to e.g. <tt/FreeFile/.
969 <sect2>VLIR structure
971 Here are informations about VLIR files (called later as RecordFile) and functions.
973 VLIR is a file which consists of up to 127 SEQ-like files called records. Each record is like one
974 SEQ structure file. Records are grouped together, described by common name - VLIR file name and
975 own number. Each record pointed by its number is described by starting track and sector numbers.
976 VLIR structures allow records to be empty (<tt/tr_se/ of such record is equal to <tt/{NULL,$ff}/),
977 or even non-exist (<tt/{NULL,NULL}/). Any other numbers represent starting track and sector of
980 In GEOS there can be only one file opened at a time. Upon opening VLIR file some information
981 about it are copied into memory. You can retrieve records table at <tt/fileTrScTab/ (table of
982 128 <tt/struct tr_se/) and from <tt/VLIRInfo/ (<tt/struct VLIR_info/.
983 E.g. size of whole VLIR file can be retrieved by reading <tt/VLIRInfo.fileSize/.
985 <sect3>OpenRecordFile
987 <tt/char OpenRecordFile (char *fName)/
989 This function finds and opens given file. An error is returned if file is not found or if it is not
990 in VLIR format. Information in <tt/VLIRInfo/ is initialized. VLIR track and sector table is
991 loaded at <tt/fileTrScTab/ and will be valid until call to <tt/CloseRecordFile/ so don't modify it.
992 You should <tt/PointRecord/ before trying to do something with file.
994 <sect3>CloseRecordFile
996 <tt/char CloseRecordFile (void)/
998 This function calls <tt/UpdateRecordFile/ and clears internal GEOS variables.
1000 <sect3>UpdateRecordFile
1002 <tt/char UpdateRecordFile (void)/
1004 This function will check <tt/VLIRInfo.fileWritten/ flag and if it is set, then <tt/curDirHead/ is
1005 updated along with size and date stamps in directory entry.
1009 <tt/char PointRecord (char recordNumber)/
1011 This function will setup internal variables (and <tt/VLIRInfo.curRecord/) and return the track and
1012 sector of given record in <tt/r1/. Note that the data may not be valid (if record is non-existing
1013 you will get 0,0 and if it is empty - 255, 0).
1015 <sect3>NextRecord and PreviousRecord
1017 <tt/char NextRecord (void)/
1019 <tt/char PreviousRecord (void)/
1021 These two work like <tt/PointRecord/. Names are self-explanatory.
1025 <tt/char AppendRecord (void)/
1027 This function will append an empty record ( pair of 255,0 ) to current VLIR track and sector
1028 table. It will also set <tt/VLIRInfo.curRecord/ to its number.
1032 <tt/char DeleteRecord (void)/
1034 This function will remove current record from the table, and move all current+1 records one place
1035 back (in the table). Note that there's no BAM update and you must call <tt/UpdateRecordFile/ to
1040 <tt/char InsertRecord (void)/
1042 This function will insert an empty record in place of <tt/VLIRInfo.curRecord/ and move all following
1043 records in table one place forward (contents of <tt/VLIRInfo.curRecord/ after call to <tt/InsertRecord/
1044 can be found in <tt/VLIRInfo.curRecord + 1/).
1046 <sect3>ReadRecord and WriteRecord
1048 <tt/char ReadRecord (char *buffer, unsigned fLength)/
1050 <tt/char WriteRecord (char *buffer, unsigned fLength)/
1052 This function will load or save at most <tt/fLength/ bytes from currently pointed record into or from
1055 <sect1>Memory and Strings
1057 Functions covered in this section are common for whole C world - copying memory parts and
1058 strings is one of the main computer tasks. GEOS also has interface to do this. These functions
1059 are replacement for those like <tt/memset, memcpy, strcpy/ etc. from standard libraries.
1061 However some of them have slighty different calling convention (order of arguments to be specific),
1062 so please check their syntax here before direct replacing.
1064 Please note that the memory described as <em/strings/ are up to 255 characters (without
1065 counting the terminating <tt/NULL/), and <em/regions/ cover whole 64K of memory.
1069 <tt/void CopyString (char *dest, char *src)/
1071 This function copies string from <tt/src/ to <tt/dest/, until it reaches <tt/NULL/. <tt/NULL/
1076 <tt/char CmpString (char *s1, char *s2)/
1078 This function compares string <tt/s1/ to <tt/s2/ for equality - this is case sensitive, and both
1079 strings have to have the same length. It returns either <tt/true/ (non-zero) or <tt/false/ (zero).
1081 <sect2>CopyFString and CmpFString
1083 <tt/void CopyFString (char length, char *dest, char *src)/
1085 <tt/char CmpFString (char length, char *s1, char *s2)/
1087 These two are similar to <tt/CopyString/ and <tt/CmpString/ except the fact, that you provide
1088 the length of copied or compared strings. The strings can also contain several <tt/NULL/
1089 characters - they are not treated as delimiters.
1093 <tt/unsigned CRC (char *src, unsigned length)/
1095 This function calculates the CRC checksum for given memory range. I don't know if it is
1096 compatible with standard CRC routines.
1098 <sect2>FillRam and ClearRam
1100 <tt/void FillRam (char *dest, char value, unsigned length)/
1102 <tt/void ClearRam (char *dest, unsigned length)/
1104 Both functions are filling given memory range. <tt/ClearRam/ fills with <tt/NULLs/, while
1105 <tt/FillRam/ uses given <tt/value/. Be warned that these functions destroy <tt/r0, r1 and
1106 r2L/ registers. <tt/FillRam/ is an alias for <tt/memset/.
1110 <tt/void MoveData (char *dest, char *src, unsigned length)/
1112 This functions copies one memory region to another. There are checks for overlap and the
1113 non-destructive method is chosen. Be warned that this function destroys contents of
1114 <tt/r0, r1 and r2/ registers. This is also alias for <tt/memcpy/
1118 <tt/void InitRam (char *table)/
1120 This function allows to initialize multiple memory locations with single bytes or strings.
1121 This is done with <tt/table/ where everything is defined. See structures chapter for description of
1122 <tt/InitRam's/ command string.
1124 <sect2>Stash, Fetch, Swap, and VerifyRAM
1126 <tt/void StashRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1128 <tt/void FetchRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1130 <tt/void SwapRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1132 <tt/ char VerifyRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1134 These functions are interface to REU - Ram Expansion Unit. I think that they are self-explanatory.
1135 You can check for REU presence by taking value of <tt/ramExpSize/.
1137 <sect1>Processes and Multitasking
1139 Weird? Not at all. GEOS has limited multitasking ability. You can set up a chain of functions
1140 called in specified intervals and you can put the main program to sleep without disturbing other
1141 tasks and making user interface unresponsive.
1143 <sect2>InitProcesses
1145 <tt/void InitProcesses (char number, struct process *processTab)/
1147 This is the main initialization routine. After calling it processes are set up, but not
1148 enabled. The parameters for <tt/InitProcesses/ are:
1150 <item><tt/number/ - number of processes
1151 <item><tt/processTab/ - table of <tt/struct process/, with size equal to <tt/number/
1154 Single task is described by entry in <tt/processTab/, it contains two values - <tt/pointer/ to
1155 task function and number of <tt/jiffies/ which describe the delay between calls to task. On PAL
1156 systems there are 50 jiffies per second, while on NTSC there are 60.
1158 The maximum number of tasks is 20. Be warned that GEOS doesn't check if parameters are valid and
1159 if <tt/processTab/ would be too large it would overwrite existing data in GEOS space.
1161 There's one important thing - the last entry in <tt/processTab/ has to be <tt/NULL,NULL/, so the
1162 maximum size of <tt/processTab/ is equal to 21.
1164 See description of <tt/process/ structure for more detailed discussion on this.
1166 <sect2>RestartProcess and EnableProcess
1168 <tt/void RestartProcess (char processNumber)/
1170 <tt/void EnableProcess (char processNumber)/
1172 These two functions start the task counter. <tt/RestartProcess/ for each process should be called
1173 after <tt/InitProcesses/, because it resets all flags and counters and it starts the counters.
1175 <tt/RestartProcess/ enables counters and sets their initial value to that given in <tt/processTab/.
1177 <tt/EnableProcess/ forces given process to execute by simulating the timer running out of time.
1179 <sect2>BlockProcess and UnBlockProcess
1181 <tt/void BlockProcess (char processNumber)/
1183 <tt/void UnBlockProcess (char processNumber)/
1185 <tt/BlockProcess/ disables the execution of given process, but this does not disable the timers.
1186 It means that if you call <tt/UnBlockProcess/ before timer runs out, the process will be executed.
1188 <tt/UnBlockProcess/ does the opposite.
1190 <sect2>FreezeProcess and UnFreezeProcess
1192 <tt/void FreezeProcess (char processNumber)/
1194 <tt/void UnFreezeProcess (char processNumber)/
1196 <tt/FreezeProcess/ disables timer for given process. <tt/UnFreezeProcess/ does the opposite.
1197 This is not equal to <tt/RestartProcess/ as timers are not filled with initial value.
1201 <tt/void Sleep (unsigned jiffies)/
1203 This function is multitasking sleep - the program is halted, but it doesn't block other functions.
1204 The only argument here is the number of jiffies to wait until app will wake up.
1206 You can force to sleep not only the main application routine, but also processes-tasks. Be warned
1207 that the maximum number of sleeping functions is 20. If it would be larger it will overwrite
1208 parameters of already sleeping functions in GEOS kernal data space, leading to crash.
1210 <sect1>System Functions
1214 <tt/void FirstInit (void)/
1216 This function initializes some GEOS variables and mouse parameters. This is called on GEOS boot
1217 up. You shouldn't use this unless you know what you are doing.
1219 <sect2>InitForIO and DoneWithIO
1221 <tt/void InitForIO (void)/
1223 <tt/void DoneWithIO (void)/
1225 These functions are called by some disk routines. You should call them only if you want to
1226 do something with IO registers or call one of Kernal's routines.
1230 <tt/void MainLoop (void)/
1232 Returns control to the system. Any code between call to <tt/MainLoop/ and the end of current
1233 function will never be executed. When in <tt/MainLoop/ systems waits for your action - using
1234 icons, keyboard or menus to force some specific action from program. You have to define
1235 proper handlers before that.
1239 <tt/void EnterDeskTop (void)/
1241 Calling this function will instantly terminate your program and bring you back to DeskTop.
1242 WARNING! It is not an equivalent of <tt/exit()/, library destructors code and functions
1243 registered with <tt/atexit()/ will not be called. In fact, you should always use
1244 <tt/exit()/ instead.
1248 <tt/void ToBASIC (void)/
1250 This one is another way of finishing application - forcing GEOS to shutdown and exit to BASIC.
1251 I was considering whether to include it or not, but maybe someone will need it. Which is I doubt.
1252 It has the same dangerous features as <tt/EnterDeskTop/.
1256 <tt/void Panic (void)/
1258 This calls system's <tt/Panic/ handler - it shows dialog box with message
1260 System error at:xxxx
1262 where <tt/xxxx/ is last known execution address (caller). By default this is bound to <tt/BRK/
1263 instruction, but it might be usable in debugging as kind of <tt/assert/. (Note that <tt/assert/
1264 is available as a separate function and will give you more information than that).
1266 System is halted after call to <tt/Panic/ which means that library destructors will not be
1267 called and some data may be lost (no wonder you're panicking).
1271 <tt/void CallRoutine (void *myFunct)/
1273 This is system caller routine. You need to provide pointer to a function and it will be immediately
1274 called, unless the pointer is equal to <tt/NULL/. This is the main functionality of this function -
1275 you don't need to check if the pointer is valid.
1277 <sect2>GetSerialNumber
1279 <tt/unsigned GetSerialNumber (void)/
1281 This function returns the serial number of system. It might be used for copy-protection.
1282 However, please remember that the Free Software is a true power and you are using it
1287 <tt/char GetRandom (void)/
1289 This function returns a random number. It can be also read from <tt/random/ e.g.
1293 but by calling this function you are sure that the results will be always different.
1294 <tt/random/ is updated once a frame (50Hz PAL) and on every call to <tt/GetRandom/.
1296 Note that it is not the same as <tt/rand/ function from the standard library. <tt/GetRandom/
1297 will give you unpredictable results (if IRQs would occur between calls to it) while
1298 <tt/rand/ conforms to the standard and for given seed (<tt/srand/) it always returns with the
1299 same sequence of values.
1303 <tt/void SetDevice (char device)/
1305 This function sets current device to given. It might be used together with <tt/InitForIO/,
1306 <tt/DoneWithIO/ and some Kernal routines. Unless new device is a disk drive this only sets
1307 new value in <tt/curDevice/, in other case new disk driver is loaded from REU or internal RAM.
1311 <tt/char get_ostype (void)/
1313 This function returns GEOS Kernal version combined (by logical OR) with machine type. Read
1314 <tt/gsys.h/ for definitions of returned values.
1318 <tt/char get_tv (void)/
1320 This function returns PAL/NTSC flag combined (by logical OR) with 40/80 columns flag. This is
1321 not the best way to check if screen has 40 or 80 columns since PAL/NTSC check is always
1322 performed and it can take as long as full raster frame. If you just want to know if
1323 screen has 40 or 80 columns use expression <tt/graphMode & 0x80/ which returns <tt/0/ for
1324 40 columns and <tt/0x80/ for 80 columns. Remember that this parameter can be changed during
1325 runtime. It is unclear if this will work for GEOS 64 so you probably do not want to test
1326 anything if not running under GEOS128. Use <tt/get_ostype/ to check it. Read <tt/gsys.h/ for
1327 definitions of returned values.
1329 <sect>Library Structures
1331 To simplify usage and optimize passing parameters to functions I have declared several structures
1332 which describe most common objects. Some of these structures are bound to static addresses in
1333 GEOS data space ($8000-$8fff), so you can use their fields directly in optimized way.
1334 Please see <tt/gsym.h/ and find them. All structures are defined in <tt/gstruct.h/ and you may
1335 find also some comments there.
1337 <sect1>Graphics Structures
1341 One simple structure describing a point on the screen.
1345 This structure describes a font in one pointsize. There is current font - <tt/struct fontdesc/
1346 bound to <tt/curFontDesc/. You can also force GEOS to use your own fonts by calling
1347 <tt/LoadCharSet/. You just need to open a VLIR font file and load one record - one pointsize
1348 somewhere. At the start of this area you already have all data for <tt/fontdesc/ so you can
1349 pass a pointer to the load adress of that pointsize to <tt/LoadCharSet/. (Note that although
1350 it has 'Load' in the name, that function loads only GEOS internal data structures, not data
1355 This widely used structure holds description of a region of the screen. It describes top-left and
1356 bottom-right corners of a window.
1360 Maybe the name isn't the best - it has nothing with <tt/DoIcons/ but with bitmap functions -
1361 <tt/BitmapUp/ for example. This structure holds parameters needed to properly decode and show
1362 a bitmap on the screen. Bitmap has to be encoded - if you have some non-GEOS bitmaps simply
1363 convert them to Photo Scraps - this is the format used by all GEOS bitmap functions - <tt/DoIcons/
1368 These structures describe click boxes (icons) that can be placed on screen or in a dialog box.
1372 This is the definition of a single click box. Please see <tt/gstruct.h/ for description of its fields.
1376 This is toplevel description of icons to be placed and enabled on the screen. This structure
1377 has following fields:
1379 <item><tt/char number/ - total number of icons declared here
1380 <item><tt/struct pixel mousepos/ - after finishing <tt/DoIcons/ mouse pointer will be placed in
1381 this point allowing you to have hint for user what is default action
1382 <item><tt/struct icondef tab[&rsqb/ - this table of size equal to <tt/icontab.number/ contains
1383 descriptions for all icons
1386 <sect1>File and Disk
1390 This simple structure holds track and sector number of something. Do not expect the track to be
1391 in range 1-35, as GEOS can support many various and weird devices. For example my C128 256K
1392 expansion is utilized as RAMDisk with layout of 4 tracks 128 sectors each. However assuming that
1393 track number equal to 0 is illegal might be wise.
1397 This is placeholder for file datestamp. This structure is also present in <tt/struct filehandle/.
1398 GEOS is not Y2K compliant, so if current file has in <tt/filehandle.date.year/ value less than 86
1399 you can safely assume that it is e.g. 2004 and not 1904.
1403 This is main file descriptor. It is either entry in the directory (returned from file functions)
1404 or its copy in <tt/dirEntryBuf/. This is optimized so you can safely get to the file's year e.g.
1405 by testing <tt/dirEntryBuf.date.year/ - it will be compiled to simple <tt/LDA, STA/.
1409 This structure holds fileheader description. You can load file's header into <tt/fileHeader/
1410 fixed area using <tt/GetFHdrInfo/. (note that <tt/fileHeader/ is a place in memory while
1411 <tt/fileheader/ is a structure).
1412 You will also need own fileheader for <tt/SaveFile/.
1414 <sect1>System Structures
1418 This structure is defined only for <tt/system_date/. It is slightly different from <tt/f_date/
1419 so I prepared this one. You can e.g. get or set current time using <tt/system_date.s_hour/ and
1420 <tt/system_date.s_minute/. Accesses to these will be optimized to simple <tt/LDA/ and <tt/STA/
1425 You should declare a table of that type to prepare data for <tt/InitProcesses/. The maximum number
1426 of processes is 20, and the last entry has to be equal to <tt/{NULL,NULL}/, so this table may hold
1427 only 21 entries. The first member of this structure (<tt/pointer/) holds the pointer to called
1428 function (void returning void), you will probably have to cast that pointer into <tt/unsigned int/.
1429 The second field <tt/jiffies/ holds the amount of time between calls to that function.
1430 On PAL systems there are 50 jiffies per second, while NTSC have 60 of them.
1432 <sect1>Few thing in detail...
1434 GEOSLib uses cc65 non-ANSI extensions to easily initialize data in memory. This is done with a
1435 kind of array of unspecified length and unspecified type. Here is how it goes:
1437 void example = {
1438 (char)3, (unsigned)3, (char)0 };
1440 Which will be compiled to following string of bytes:
1447 As you see this way it is possible to define data of any type in any order. You must remember to
1448 cast each member to proper type.
1450 <sect2>DoMenu structure
1452 <tt/DoMenu/ is responsible for everything concerned with menu processing. Many, many GEOS programs
1453 are just initializing screen and menu and exit to <tt/MainLoop/. In GEOSLib it is the same as
1454 returning from <tt/main/ function without using <tt/exit(0)/.
1456 Menu is described by two types of data - menu descriptors and menu items. Descriptor contains
1457 information about following menu items, and items are containing names of entries and either
1458 pointers to functions to execute or, in case of nested menus, pointers to submenu descriptors.
1459 Note that submenu descriptor can be top-level descriptor, there's no difference in structure,
1460 just in the content.
1462 Here is how single descriptor looks like:
1464 void myMenu = {
1465 (char)top, (char)bottom, // this is the size of the menubox
1466 (unsigned)left, (unsigned)right, // counting all items in current descriptor
1467 (char)number_of_items | type_of_menu, // number of following items ORed with
1468 // type of this menu, it can be either
1469 // HORIZONTAL or VERTICAL if you will have also bit 6 set then menu won't be closed
1470 // after moving mouse pointer outside the menubox. You can have at most 31 items.
1472 This is followed by <tt/number_of_items/ of following item description.
1475 "menuitemname", (char)item_type, (unsigned)pointer,
1476 "nextitemname", (char)item_type, (unsigned)pointer,
1478 "lastitemname", (char)item_type, (unsigned)pointer };
1479 // Note that there isn't ending <tt/NULL/ or something like that.
1481 <tt/pointer/ is a pointer to something, what it points for depends from <tt/item_type/. This one
1482 can have following values:
1484 <tt/MENU_ACTION/ - a function pointed by <tt/pointer/ will be called after clicking on menu item
1486 <tt/SUB_MENU/ - <tt/pointer/ points to next menu descriptor - a submenu
1488 Both of them can be ORed with <tt/DYN_SUB_MENU/ and then the <tt/pointer/ points to a function
1489 which will return in <tt/r0/ needed pointer (to function to execute or a submenu).
1491 For creating nested menus (you can have at most 8 levels of submenus) you need to declare such
1492 structure for each submenu and top level menu.
1494 <sect2>DoDlgBox command string
1496 <tt/DoDlgBox/ is together with <tt/DoMenu/ one of the most powerful routines in GEOS. It is
1497 responsible for creating dialog boxes, that is windows which task is to interact with user.
1498 Format of the command string is following:
1500 (window size and position)
1501 (commands and parameters)
1504 There is custom type defined for the command string: <tt/dlgBoxStr/.
1506 <sect3>Size and position
1508 The first element can be specified in two ways - by using default size and position or specifying
1509 own. The first case results in
1511 const dlgBoxStr example = {
1512 DB_DEFPOS (pattern_of_shadow),
1516 And the own size and position would be:
1518 const dlgBoxStr example = {
1519 DB_SETPOS (pattern, top, bottom, left, right)
1526 The next element of <tt/DoDlgBox/ command string are commands themselves. First six commands are
1527 default icons and the number of selected icon will be returned from window processor. The icons are
1528 <tt/OK, CANCEL, YES, NO, OPEN/, and <tt/DISK/. You can use predefined macros for use them, e.g.:
1531 DB_ICON(OK, DBI_X_0, DBI_Y_0),
1534 Note that the position is counted from top left corner of window, not entire screen and that the 'x'
1535 position is counted in cards (8-pixel) and not in pixels. This is true also for all following commands.
1536 <tt/DBI_X_0/ and <tt/DBI_Y_0/ are predefined (see <tt/gdlgbox.h/ for more), default positions
1537 which will make icons to appear on default window exactly where you would expect them.
1539 <tt/DB_TXTSTR (x, y, text)/ will cause to show given text in the window.
1541 <tt/DB_VARSTR (x, y, ptr)/ works as above, but here you are passing a pointer to a zero page location
1542 where the address of text is stored. This is useful for information windows where only text content
1543 is variable. Consider following:
1547 r15=(unsigned)text; // in code just before call to DoDlgBox
1549 DB_VARSTR (TXT_LN_X, TXT_LN_1_Y, &r15),
1552 will cause to appear the word ``foo'' in the window, but you may store the pointer to any text in
1553 <tt/r15/ (in this case) before call to DoDlgBox.
1555 <tt/DB_GETSTR(x, y, ptr, length)/ - will add input from keyboard feature. <tt/ptr/ works as in
1556 previous example and points to place where text is to be stored. Note that the contents of this
1557 place will be shown upon creating window. <tt/length/ is the maximum number of characters to input.
1559 <tt/DB_SYSOPV(ptr)/ - this sets <tt/otherPressVec/ to given pointer. It is called on every keypress.
1561 <tt/DB_GRPHSTR(ptr)/ - data for this command is the pointer for <tt/GraphicsString/ commands.
1563 <tt/DB_GETFILES(x, y)/ - for standard window you should pass 4 for both x and y. This function
1564 draws file selection box and searches current drive for files. Before call to <tt/DoDlgBox/ you
1565 must load <tt/r7L/ with GEOS filetype of searched files and <tt/r10/ with class text. In <tt/r5/
1566 you have to load pointer to a <tt/char[17]/ where selected filename will be copied. It works
1567 like <tt/FindFTypes/ but is limited to first 16 files.
1569 <tt/DB_OPVEC(ptr)/ - this sets the new pointer for button press function, if you pass
1570 <tt/RstrFrmDialogue/ here you will cause the window to close after pressing mouse button.
1572 <tt/DB_USRICON(x, y, ptr)/ - places single user icon (click box) on window, <tt/ptr/ points at a
1573 <tt/struct icondef/ but fields <tt/x/ and <tt/y/ are not used here. You can have at most 8 click
1574 boxes in a window, this is internal limit of GEOS Kernal.
1576 <tt/DB_USRROUT(ptr)/ - this command causes to immediately call user routine pointed by <tt/ptr/.
1578 <sect2>GraphicsString command string
1580 <tt/GraphicsString/ is a very powerful routine to initialize whole screen at once. There are
1581 predefined macros for all commands, names are self-explanatory, see them in <tt/ggraph.h/. Last
1582 command have to be <tt/GSTR_END/. There is custom type defined for the command string: <tt/graphicStr/.
1584 Here is an example for clearing the screen:
1586 const graphicStr example = {
1589 RECTANGLETO(319,199)
1593 <sect2>InitRam table
1595 This type of data is used to initialize one or more bytes in many places at once. The format is
1598 void example = {
1599 (unsigned)address_to_store_values_at,
1600 (char)number_of_bytes_that_follow,
1601 (char)data,(char)data (...)
1602 // more such definitions
1603 (unsigned)NULL // address of 0 ends the table
1607 <sect2>Intercepting system vectors
1609 It is possible to intercept and hook in the GEOS Kernal using vectors. Here is a little example:
1611 void_func oldVector;
1613 void NewVectorHandler(void) {
1614 // do something and at the end call the old vector routine
1618 void hook_into_system(void) {
1619 oldVector = mouseVector;
1620 mouseVector = NewVectorHandler;
1623 void remove_hook(void) {
1624 mouseVector = oldVector;
1628 In your <tt/main/ function you should call <tt/hook_into_system()/ but <em/after/ all calls to GEOS
1629 kernal (like <tt/DoMenu/, <tt/DoIcons/, etc.) - right before passing control to the <tt/MainLoop()/.
1630 It is critical to restore old vector values before exiting the program. If you have more than one
1631 place where you call <tt/exit()/ then it might be worth to register <tt/remove_hook/ function to
1632 be called upon exiting with <tt/atexit(&remove_hook);/ call. This way you will ensure that
1633 such destructor will be always called.
1635 That little example above intercepts <tt/mouseVector/. The <tt/NewVectorHandler/ function will be
1636 called every time the mouse button changes status. Other important vectors you should know about
1639 <item><tt/appMain/ - this is called from within <tt/MainLoop/ system loop
1640 <item><tt/keyVector/ - called whenever a keypress occurs
1641 <item><tt/intTopVector/ - called at the start of IRQ routine
1642 <item><tt/intBotVector/ - called at the end of IRQ routine