1 <!doctype linuxdoc system>
5 <author><url url="mailto:ytm@elysium.pl" name="Maciej Witkowiak">
8 This is the documentation of cc65's GEOSLib, but information contained here may be also
9 useful for writing GEOS applications in general.
12 <!-- Table of contents -->
15 <!-- Begin the document -->
19 As we all know that the best computers in the world are the C64 and C128. They have their GUI too -
20 the excellent GEOS. GEOS seems very difficult and cryptic for many people, from programmer's point
21 of view. That's not true. The designers of GEOS created a flexible and powerful system, which
22 is easy to use and program.
24 Coding GEOS in C? That's something new. It is possible now - with Ulrich von Bassewitz's cc65
25 package and my GEOSLib you are able to create GEOS applications in no time.
27 GEOSLib supports a subset of the standard cc65 libraries. Whenever possible native Kernal functions
28 are used (e.g. <tt/memset/ is an alias for <tt/FillRam/), however not all are supported. E.g.
29 string functions like <tt/strcmp/, <tt/strcpy/ are doubled with native <tt/CmpString/,
30 <tt/CopyString/ because the latter can handle only 256 byte strings. Keep this in mind when
31 you write your program. If you don't need long strings simply use functions from the Kernal,
32 the resulting code will be smaller.
34 <tt/dio/ - direct disk access is available, but you might have problems with devices other
35 than 1541, 1571 or 1581. RAM drives emulating these should work.
37 <tt/conio/ - simple console input-output is available for command line applications.
38 This implementation assumes that one character does fit in 8x8 cell, so output with
39 default BSW font, which is has 9 points, might be a bit messy. There is no color support in
40 GEOS 2.0 so color functions are disabled. Both 40 and 80 column modes are supported
41 and automatically detected.
43 <tt/tgi/ - TGI driver for GEOS that supports both 40 and 80 column modes but mode can not be
44 changed between <tt/tgi_init/ and <tt/tgi_done/.
46 <tt/joy/ - JOY driver for GEOS that supports only joystick, not current pointing device.
48 It is safe to use these standard includes and their contents:
49 <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/
51 For <tt/time.h/ functions <tt/systime()/ and <tt/clock()/ note that the resolution is one second.
53 Functions from the headers above are either standard C library functions or cc65-specific, in
54 either case they are not GEOS specific and so they are not described here.
56 I am an assembler programmer and GEOSLib was designed in such way that cc65 could emit the best
57 available code (well, the best as for machine :-). Many of the <tt/void foo (void)/ functions are
58 just raw calls to the Kernal (assembled just as <tt/jsr _foo/), look in <tt/gsym.h/, where you
59 can find many definitions of standard GEOS locations. Access to these addresses is optimized by
60 cc65 to simple <tt/lda/ and <tt/sta/. Don't be afraid to use C syntax.
64 You don't need a C64 or C128 for development. The only hardware requirement is a PC capable of
65 running cc65. You do however need C64 or C128 emulator and GEOS disk images (.d64) to test your
70 <item><em/cc65/ Excellent package containing a C crosscompiler, a crossassembler and a linker, you
71 can get it from: <url url="http://cc65.github.io/cc65/">.
72 <item><em/VICE/ This is a portable C64, C128 and few other Commodore computers emulator, you
73 can obtain it from: <url url="http://vice-emu.sourceforge.net/">.
74 The VICE package contains the <em/c1541/ program that is able
75 to convert/unconvert GEOS files to disk images.
76 <item><em/The Star Commander/ This tool is only for DOS. You will need it for transferring
77 object files from a PC to a 1541. There's also one important ability of this
78 tool - it automatically un-converts .cvt files into GEOS native format on
79 disk image files. Check out: <url url="http://sta.c64.org/sc.html">.
80 <item><em/opencbm/ A package that allows for communication directly with a 1541 and
81 other Commodore IEC bus drives. It can be a replacement for Star Commander if
82 you only want to transfer files to a disk and unconvert using GEOS program for
83 this purpose. Check out: <url url="http://opencbm.sourceforge.net/">.
86 VICE and cc65 are portable - they run on variety of platforms - DOS, Win32 and UNIX. GEOSLib only
89 <em/Update:/ starting from v2.5.0 GEOSLib is a part of the cc65 package as its GEOS support library.
93 I want to thank Uz for his cc65 package, Alexander Boyce for his excellent GEOS Programmer's
94 Reference Guide and BSW for GEOS.
96 GEOSLib is covered by the same license as cc65. You can find the whole text
97 among documentation. I would really appreciate if you would like to send me
98 your comments, suggestions, questions, changes, bug reports etc. I will also
99 appreciate if you will just give me a sign that you are using GEOSLib - not
100 especially something big and important, mail me even if you are just playing
103 You can send postcards with hellos to:
105 Maciej Witkowiak, ul. Slowackiego 6/57, 77-400 ZLOTOW
109 e-mail: <tt/ytm@elysium.pl/
111 <sect>What do you have and what to do with it?
113 This chapter describes some rules you ought to obey, and how to use GEOSLib.
117 Apart from this file, which merely describes only standard GEOS library
118 functions, you should read the <tt/grc65/ (GEOS resource compiler) documentation.
119 There is information about necessary resource files (each GEOS application
120 needs at least one) and the build process - what should be done and in what
121 order. Please also read the cc65 documentation on how to compile C, assembler
122 and link everything together.
124 All in all, you just need to place
126 #include <geos.h>
128 at the top of your source.
130 As a general rule read the sources of the example programs and read the headers.
131 These are the most reliable sources of knowledge ;-). You will also find there
132 many C macros representing various arguments passed to the functions. Please use
133 them. You will find your sources easier to understand, and it will be easier
136 All types used in GEOSLib are <tt/unsigned/.
138 Screen coordinates are given in pixels unless stated differently.
140 <sect1>Notes on style
142 Contrary to a typical GEOS assembly program which has a main function called after loading that
143 setups the screen, menus, icons etc. exiting from the <tt/main/ function in C is equivalent to
144 calling <tt/exit()/. These two are the only safe methods of terminating applications. DO NOT
145 USE <tt/EnterDeskTop/! Your data may be lost as library destructors and functions registered
146 with <tt/atexit/ are not called.
148 For GEOS GUI applications the recommended program structure is to have everything initialized
149 in the <tt/main/ function and at the end of it a call to the <tt/MainLoop()/ function. WARNING! This
150 function never returns, any code between <tt/MainLoop();/ and the end of <tt/main/ will not
151 be executed. You have to call <tt/exit()/ explicitly somewhere in your code (e.g. in a menu
152 handler or via DialogBox action).
154 Whenever possible use definitions from <tt/gsym.h/. The resulting code is translated by cc65 into
155 series of <tt/lda/ and <tt/sta/, so you can't do it better :-).
157 Don't hesitate to use library functions. Everything was written with size and speed in mind. In
158 fact many calls are just redirections to the GEOS Kernal which results in a simple <tt/jsr/.
160 The <tt/main/ function receives the standard <tt/argc/ and <tt/argv/ parameters. There are
161 always either 1 or 3 parameters. The DOS application name is always set as <tt/argv[0]/.
162 If present, <tt/argv[1]/ and <tt/argv[2]/ will be set to the data filename and data diskname (it only
163 works if the user double-clicks on a data file associated with your application). Note that it is up
164 to your application to determine which of the available (up to four) disk drives has the disk
165 with given diskname inside. If this fails your program should ask to insert the proper disk into
166 one of available drives.
168 You might wonder why I have chosen a sometimes weird order of arguments in functions. I just
169 wanted to avoid unnecessary pushing and popping of arguments from the stack because cc65 can pass a single
170 <tt/unsigned int/ through CPU registers.
172 Do not try to compile in strict ANSI mode. The library uses cc65 extensions which are not available in
175 It is possible to use dynamically loaded modules, three such modules are provided:
176 A GEOS TGI driver, a GEOS EMD driver (for VDC extended memory) and a GEOS JOY driver.
177 Just make sure that their filenames appear UPPERCASE in DeskTop. There are no more special
178 recommendations, read the cc65 documentation about modules and the demo programs source code.
180 <sect>Library Functions
182 Functions here are sorted more or less in the way they appear in the header files. This way I am able
183 to keep functions covering similar tasks near each other. All function names are identical to those
184 from the <tt/geosSym/ file provided with the GeoProgrammer package. Only my extensions to <tt/geosSym/
185 are covered by new names, but I tried to keep them in the naming convention.
189 This section covers the drawing package of GEOS along with text output routines.
193 <tt/void SetPattern (char pattern)/
195 This function sets the current pattern to the given. There are 32 different patterns in GEOS. You can
196 see them together in the filling box in GeoPaint.
198 <sect2>GraphicsString
200 <tt/void GraphicsString (char *myGString)/
202 One of the more powerfull routines of GEOS. This function calls other graphic functions depending
203 on the given command string. See the structures chapter for a more detailed description.
205 <sect2>Rectangle functions
207 Parameters to those functions are grouped in the <tt/struct window drawWindow/. To speed up things and
208 reduce overhead this structure is bound to zero page locations, where all rectangle functions
209 expect their parameters. You can modify the data directly (e.g. <tt/drawWindow.top=10/) or via the
210 <tt/InitDrawWindow/ function. Contents of <tt/drawWindow/ are guaranteed not to change when only
211 using graphics functions. In other cases you should keep your data in separate <tt/struct window/
212 and use <tt/InitDrawWindow/ before the first call to one of the rectangle functions.
214 <sect3>InitDrawWindow
216 <tt/void InitDrawWindow (struct window *myWindow)/
218 This function only copies the contents of <tt/myWindow/ into the system area of <tt/drawWindow/. Use it
219 if for some reason you have to keep your window data out of the zero page space.
223 <tt/void Rectangle (void)/
225 This draws on screen a rectangle filled with the current pattern.
227 <sect3>FrameRectangle
229 <tt/void FrameRectangle (char pattern)/
231 This one draws a frame with the given bit pattern (not a pattern from the GEOS palette).
233 <sect3>InvertRectangle
235 <tt/void InvertRectangle (void)/
237 Just as the name says...
239 <sect3>ImprintRectangle and RecoverRectangle
241 <tt/void ImprintRectangle (void)/
243 <tt/void RecoverRectangle (void)/
245 These two functions are for copying parts of the screen to (<tt/Imprint/) and from (<tt/Recover/) the
246 backbuffer of the screen. For example when drawing a new menu box GEOS first uses
247 <tt/ImprintRectangle/ to save the area under the box, and restores it by <tt/RecoverRectangle/ upon
250 <sect2>Line Functions
252 The GEOS drawing package is optimized so there are different functions for drawing vertical and
255 <sect3>HorizontalLine
257 <tt/void HorizontalLine (char pattern, char y, unsigned xStart, unsigned xEnd)/
259 This function draws a horizontal line using the given pattern. Note that <tt/pattern/ is not a pattern
260 number as set in <tt/SetPattern/ but a true bit pattern.
264 <tt/void InvertLine (char y, unsigned xStart, unsigned xEnd)/
266 There is only a horizontal version.
270 <tt/void RecoverLine (char y, unsigned xStart, unsigned xEnd)/
272 This function recovers a single line. It is utilized by <tt/RecoverRectangle/. See its description
277 <tt/void VerticalLine (char pattern, char yStart, char yEnd, unsigned x)/
279 This function draws a vertical line using the given pattern. Note that <tt/pattern/ is not a pattern
280 number as set in <tt/SetPattern/ but a true bit pattern.
284 <tt/void DrawLine (char mode, struct window *myWindow)/
286 The <tt/top/ parameters of <tt/struct window/ describe the starting point of the line, while
287 <tt/bottom/ ones are for the ending point. If <tt/mode/ is <tt/DRAW_DRAW/ then the current pattern from
288 <tt/SetPattern/ is used for drawing. If <tt/mode/ is <tt/DRAW_ERASE/ then the line is erased from the
289 screen. If <tt/mode/ is <tt/DRAW_COPY/ then the line is copied from/to back/frontbuffer, according to
290 the <tt/dispBufferOn/ setting.
292 <sect2>Point Functions
294 The parameters to these two functions are passed by a pointer to an own <tt/struct pixel/ filled with
299 <tt/void DrawPoint (char mode, struct pixel *myPixel)/
301 Depending on <tt/mode/ (see <tt/DrawLine/) draws/erases/copies a single point
306 <tt/char TestPoint (struct pixel *myPixel)/
308 This function tests if the given pixel is set and returns <tt/true/ (non-zero) or <tt/false/ (zero).
310 <sect2>Character and string output
314 <tt/void PutChar (char character, char y, unsigned x)/
316 This function outputs a single character using the current style and font to the screen.
320 <tt/void PutString (char *myString, char y, unsigned x)/
322 Same as <tt/PutChar/ except the fact that you can output a whole <tt/NULL/-terminated string.
323 See <tt/ggraph.h/ for the list of tokens that you can also place in the string - like <tt/CBOLDON/ or
328 <tt/void PutDecimal (char parameter, unsigned value, char y, unsigned x)/
330 This function converts <tt/value/ to its decimal representation and outputs it to the screen.
331 The <tt/parameter/ is the field width in pixels (range 1-31) and the mode bits. Depending on them
332 the string can be filled with zeroes (the string is always 5 characters long) or not and left or right
333 justified to the given pixel. See <tt/ggraph.h/ for predefined values for <tt/parameter/.
339 <tt/char GetCharWidth (char character)/
341 This function returns the real width (in pixels) of the given character with the current font. It can be used
342 for counting the length of a string on the screen, allowing for indentation or justification.
346 <tt/void LoadCharSet (struct fontdesc *myFont)/
348 This function forces GEOS to use the given font. <tt/myFont/ should be casted from a
349 pointer to the start of the area where a record from a font file (VLIR structure) was loaded.
353 <tt/void UseSystemFont (void)/
355 This function forces GEOS to use the built-in BSW font.
357 <sect2>Bitmap handling
359 I'm not quite sure how these functions are working (except <tt/BitmapUp/) so you should
360 probably look into the library sources and compare it with your knowledge. Please let me know
361 if something is wrong or broken.
365 <tt/void BitmapUp (struct iconpic *myPic)/
367 This function unpacks the bitmap and places it on the screen - just as you set it in the
368 <tt/struct iconpic/ pointer which you pass. See <tt/gstruct.h/ for a description of this
369 structure. Note that you can only use packed GEOS bitmaps - a simple Photo Scrap is in this format.
373 <tt/void BitmapClip (char skipLeft, char skipRight, unsigned skipTop, struct iconpic *myPic)/
375 This function acts similar to <tt/BitmapUp/ but you can also define which parts of the bitmap are
376 to be drawn - you give the number of columns (8-pixel) to skip on the right and left of the bitmap,
377 and the number of rows to skip from the top if it.
381 <tt/void BitOtherClip (void *proc1, void *proc2, char skipLeft, char skip Right, unsigned skipTop,
382 struct iconpic *myPic)/
384 Similar to the previous one with some extension. <tt/proc1/ is called before reading a byte (it
385 returns in .A the next value), and <tt/proc2/ is called every time the parser reads a byte which is
386 not a piece of a pattern (byte of code greater than 219). Both procedures should be written
387 separately in assembler and declared as <tt/__fastcall__/ returning char.
389 <sect1>Menus and Icons
391 Here you will find information about functions related with menus and icons.
395 Menus are essential for a GUI. GEOS can handle only one menu at a time, but each menu can call
396 another one, which results in a submenu tree. There can be up to 8 menu levels, each one with up
399 Menus are initialized with <tt/DoMenu/ and then the Kernal takes care of everything. Your code
400 (called from an event handler) should be a function without parameters, returning void. You should
401 use <tt/DoPreviousMenu/ or <tt/GotoFirstMenu/ at least once in its code to have the screen clean.
405 <tt/void DoMenu (struct menu *myMenu)/
407 This function initializes the GEOS menu processor and exits. See <tt/DoMenu structure/ for more
408 information about it. Know that many GEOS applications just initialize the screen, menu and
409 exit to the main Kernal loop, this proves the power of <tt/DoMenu/.
413 <tt/void ReDoMenu (void)/
415 This simply redraws the menu at the lowest level. It works like calling <tt/DoMenu/ again with
420 <tt/void RecoverMenu (void)/
422 This function erases the current menu from the screen. It doesn't change the menu level.
424 <sect3>RecoverAllMenus
426 <tt/void RecoverAllMenus (void)/
428 This calls <tt/RecoverMenu/ and erases all menus from the screen. Then the menu level is
431 <sect3>DoPreviousMenu
433 <tt/void DoPreviousMenu (void)/
435 This functions causes the menu processor to go back one menu level. You should use it in menu
436 handler code to have the screen clean.
440 <tt/void GotoFirstMenu (void)/
442 This one jumps back to the topmost menu. If there is only a menu and one submenu it works the
443 same as <tt/DoPreviousMenu/.
445 <sect2>Icon Functions
447 Icons are working similar to menus except the fact that there is only one level. Icons are
448 defined as a screen area filled with a bitmap, but if you would setup icons and erase the
449 screen they would still be active and clicking in the place where formerly an icon was would cause
450 an effect. Similarly if you would setup icons and then turn them off with <tt/ClearMouseMode/
451 the bitmap would still be on the screen but clicking on it would not cause any action.
452 There is only one, but powerful icon function.
456 <tt/void DoIcons (struct icontab *myIconTab)/
458 This function initializes all icons that are present on the screen at once. For more information
459 look at the <tt/Icons/ chapter in this manual.
463 This chapter covers the most powerful GEOS user interface function - <tt/DoDlgBox/.
469 <tt/char DoDlgBox (char *dialogString)/
471 This function returns one byte. It can be the value of one of six standard icons (see <tt/gdlgbox.h/)
472 or whatever the closing routine passes. Register <tt/r0L/ also contains this value.
474 Read the structures chapter for the specs of the <tt/dialogString/.
476 <sect3>RstrFrmDialogue
478 <tt/char RstrFrmDialogue/
480 This function is called from within DoDlgBox event. It immediately closes the DialogBox and returns
481 the owner ID (or whatever caller has in the .A register).
483 <sect2>GEOSLib extensions
485 To simplify the usage of DoDlgBox from C I wrote some helper functions - wrappers for DoDlgBox,
486 with predefined data. In one word - these are standard DialogBoxes you can see in almost every
489 <sect3>DlgBoxYesNo, DlgBoxOkCancel, DlgBoxOk
491 <tt/char DlgBoxYesNo (char *line1, char *line2)/
493 <tt/char DlgBoxOkCancel (char *line1, char *line2)/
495 <tt/void DlgBoxOk (char *line1, char *line2)/
497 These function show two lines of text in a standard-sized DialogBox. You can read the code of the
498 pressed icon from the return value. E.g. for <tt/DlgBoxYesNo/ it can only be <tt/YES/ or <tt/NO/.
499 You can pass an empty string or NULL to get a blank line.
501 <sect3>DlgBoxGetString
503 <tt/char DlgBoxGetString (char *string, char strlen, char *line1, char *line2)/
505 This function prompts the user to enter a string of at most <tt/strlen/ characters. It is returned
506 in <tt/string/. The two given lines of text are shown above the input line. Please remember
507 that there is also a <tt/CANCEL/ icon in the DialogBox and you should test if user confirmed his
508 input or gave up. The <tt/string/ is also shown so you can place a default input there or remember
509 to place <tt/NULL/ at start.
511 <sect3>DlgBoxFileSelect
513 <tt/char DlgBoxFileSelect (char *class, char filetype, char *filename)/
515 This routine is the standard file selector. It can return <tt/OPEN/, <tt/CANCEL/ or disk error
516 on reading the directory or opening the disk.
517 There is also a <tt/DISK/ icon shown, but it is handled internally. You pass as input parameters
518 <tt/filetype/ and a pointer to a string containing the first part of a file's class. If this string is
519 empty (<tt/NULL/ at the start), then all files with given filetype will be shown.
521 At present this file selector handles only first 16 files of given type and supports only one
526 <tt/char MessageBox (char mode, const char *format, ...)/
528 This function is a more general one. It works very much like <tt/printf/ in a
529 box. The only difference is the <tt/mode/ parameter which allows for placing
530 default icons (see <tt/gdlgbox.h/ for list of possible <tt/MB_/ values).
531 Any too wide text will be clipped to the size of the default window. If <tt/mode/
532 is invalid or equal to <tt/MB_EMPTY/ then the window will be closed
533 after a click. Otherwise the user must choose an icon.
535 Note: Use it if you really need (or if you use it in many places) as
536 it adds quite amount of code to your program.
538 Note: the formatted text <em/cannot exceed/ 255 bytes in length, there is no check
541 <sect1>Mouse, Sprites and Cursors
543 You will find here functions related to sprite and mouse drawing and handling.
545 <sect2>Mouse related functions
547 These cover the mouse - as a general pointing device, but expect users to utilize as different devices
548 as a digital or analog joystick, a mouse, a lightpen or a koalapad (whatever it is).
550 <sect3>StartMouseMode
552 <tt/void StartMouseMode (void)/
554 This function initializes the mouse vectors - <tt/mouseVector/ and <tt/mouseFaultVec/, and then
557 <sect3>ClearMouseMode
559 <tt/void ClearMouseMode (void)/
561 This function disables all mouse activities - icons and menus stop to respond to mouse events,
562 but they are not cleared from the screen.
564 <sect3>MouseUp and MouseOff
566 <tt/void MouseUp (void)/
568 <tt/void MouseOff (void)/
570 The first function turns the mouse pointer on. It appears on the next IRQ. The second one does
571 the opposite - it turns off the pointer, but its position is still updated by the input driver.
575 <tt/char IsMseInRegion (struct window *myWindow)/
577 This function tests if the mouse pointer is actually in the given range of the screen. See <tt/gsprite.h/ for
578 a description of the bits in the return values - they describe the position in detail.
582 You are free to use any of the eight sprites, but keep in mind that sprite 0 is actually the mouse
583 pointer and sprite 1 can be overwritten when using a text prompt. You don't have to worry about
584 40/80 column issues because GEOS128 has a pretty good sprite emulator for the VDC.
588 <tt/void DrawSprite (char sprite, char *mySprite)/
590 This function initializes the sprite data. <tt/mySprite/ is a 63-byte table with bitmap data, which
591 is copied to the system sprite area (at <tt/sprpic/ - see <tt/gsym.h/). Hardware sprite registers are
592 not initialized and the sprite is not yet visible.
596 <tt/void PosSprite (char sprite, struct pixel *myPixel)/
598 This function positions the sprite on the screen. The given coordinates are screen ones - they are
599 converted to sprite coordinates by GEOS. Due to this you cannot use this function to position your
600 sprite off the left or top to the screen.
602 <sect3>EnablSprite and DisablSprite
604 <tt/void EnablSprite (char sprite)/
606 <tt/void DisablSprite (char sprite)/
608 These two functions are responsible for making the sprite visible or not.
610 <sect2>Cursors and Console
612 <sect3>InitTextPrompt
614 <tt/void InitTextPrompt (char height)/
616 This function initializes sprite 1 for a text prompt with given <tt/height/. This parameter can be in
619 <sect3>PromptOn and PromptOff
621 <tt/void PromptOn (struct pixel *myPixel)/
623 <tt/void PromptOff (void)/
625 The first function places a text prompt in given place and enables blinking.
626 The second one is pretty self-explanatory.
630 <tt/char GetNextChar (void)/
632 This function gets the next character from the keyboard queue. If the queue is empty it returns
633 <tt/NULL/, otherwise you receive the true ASCII code of a character or the value of a special (function)
634 key. See <tt/gsprite.h/ for the list of them.
638 This chapter covers rather low-level disk routines. You should use them with care, because
639 you may easily corrupt data on disks. Also remember that contemporary GEOS supports many various
640 devices and sticking to 1541 track layout (e.g. expecting the directory on track 18) might be
643 For some purposes you might consider using the <tt/dio.h/ interface to disk access. It is native.
645 All GEOS disk functions return an error code in the X register. In some cases this is returned by the
646 GEOSLib function (if its type is <tt/char/), but in all cases the last error is saved in the <tt/__oserror/
647 location. If it is nonzero - an error occured. See <tt/gdisk.h/ for the list of possible errorcodes.
648 You need to include <tt/errno.h/ to get <tt/__oserror/, together with the standard <tt/errno/. The
649 latter gives less verbose, but still usable information and can be used with <tt/strerror/.
650 Probably you will get more information using <tt/_stroserror/ in a similar way.
652 For passing parameters use almost always a pointer to your data e.g. <tt/ReadBuff (&myTrSe)/.
654 <sect2>Buffer functions
656 These functions take a single data sector (256 bytes) to read or write on the disk.
658 <sect3>ReadBuff and Writebuff
660 <tt/char ReadBuff (struct tr_se *myTrSe)/
662 <tt/char WriteBuff (struct tr_se *myTrSe)/
664 These functions read and write a sector placed at <tt/diskBlkBuf/.
666 <sect3>GetBlock and ReadBlock
668 <tt/char GetBlock (struct tr_se *myTrSe, char *buffer)/
670 <tt/char ReadBlock (struct tr_se *myTrSe, char *buffer)/
672 These two functions read a single block directly to the 256 byte array placed at <tt/buffer/.
673 The difference between them is that <tt/GetBlock/ initializes TurboDos in the drive if it was not
674 enabled. <tt/ReadBlock/ assumes that it is already enabled thus being slightly faster.
676 <sect3>PutBlock, WriteBlock, VerWriteBlock
678 <tt/char PutBlock (struct tr_se *myTrSe, char *buffer)/
680 <tt/char WriteBlock (struct tr_se *myTrSe, char *buffer)/
682 <tt/char VerWriteBlock (struct tr_se *myTrSe, char *buffer)/
684 Similar to previous but needed for writing the disk. <tt/VerWriteBlock/ verifies the data after
685 writing. In case of an error five tries are attempted before an error code is returned.
687 <sect2>Directory header
689 The functions described here operate on <tt/curDirHeader/ where the current disk header is stored.
690 On larger (than 1541) capacity drives the second part of the directory header is in <tt/dir2Head/.
694 <tt/void GetPtrCurDkNm (char *diskName)/
696 This function fills the given character string with the name of current disk. It is converted to C
697 standard - the string is terminated with <tt/NULL/ character instead of code 160 as in Commodore DOS.
698 Note that the passed pointer must point to an array of at least 17 bytes.
700 <sect3>GetDirHead and PutDirHead
702 <tt/char GetDirHead (void)/
704 <tt/char PutDirHead (void)/
706 These functions read and write the directory header. You should use <tt/GetDirHead/ before
707 using any functions described below, and you should use <tt/PutDirHead/ to save the changes on the
708 disk. Otherwise they will be lost. Operating area is the <tt/curDirHead/.
712 <tt/unsigned CalcBlksFree (void)/
714 This function returns the number of free blocks on the current disk. It is counted using data in
715 <tt/curDirHead/ so you must initialize the disk before calling it.
719 <tt/char ChkDskGEOS (void)/
721 This functions checks <tt/curDirHead/ for the GEOS Format identifier. It returns either true or false,
722 and also sets <tt/isGEOS/ properly. You must initialize the disk before using this.
726 <tt/char SetGEOSDisk (void)/
728 This function initializes disk for use with GEOS. It sets the indicator in directory header and
729 allocates a sector for the directory of border files. You don't need to initialize the disk before
734 <tt/char FindBAMBit (struct tr_se *myTrSe)/
736 This function returns the bit value from the BAM (Block Allocation Map) for the given sector. The bit is
737 set if the sector is free to use. The returned value is always zero if the sector is already allocated.
738 In fact, this function could be used in a following way:
740 #define BlockInUse FindBAMBit
742 if (!BlockInUse(&myTrSe)) {
743 ... block not allocated ...
747 Anyway, I feel that this function is too low-level.
749 <sect3>BlkAlloc and NxtBlkAlloc
751 <tt/char BlkAlloc (struct tr_se output[&rsqb, unsigned length)/
753 <tt/char NxtBlkAlloc (struct tr_se *myTrSe, struct tr_se output[&rsqb, unsigned length)/
755 Both functions allocate enough disk sectors to fit <tt/length/ bytes in them. You
756 find the output in <tt/output/ which is a table of <tt/struct tr_se/. The last entry will have the
757 track equal to 0 and sector equal to 255. The simplest way of using them is to use
758 predefined space in the GEOS data space and pass <tt/fileTrScTab/, which is a predefined table.
760 The difference between those two is that <tt/NextBlkAlloc/ starts allocating from the given sector,
761 and <tt/BlkAlloc/ starts from the first nonused sector.
763 You need to use <tt/PutDirHead/ later to save any changes in BAM.
767 <tt/char FreeBlock (struct tr_se *myTrSe)/
769 Simply deallocates a block in the BAM. You need to update the BAM with <tt/PutDirHead/.
773 <tt/struct tr_se SetNextFree (struct tr_se *myTrSe)/
775 This function finds the first free sector starting from given track and sector and allocates it.
776 It might return the same argument if the given block is not allocated. I wanted it to be type
777 clean, but this made the usage a bit tricky. To assign a value to your own <tt/struct tr_se/ you have to
778 cast both variables to <tt/unsigned/. E.g.
782 (unsigned)myTrSe=(unsigned)SetNextFree(&otherTrSe);
785 In this example <tt/otherTrSe/ can be replaced by <tt/myTrSe/.
787 Note: you <em/must/ use casting to have the correct values.
789 <sect2>Low-level disk IO
791 Functions described here are more usable in Kernal or drivers code, less common in applications,
792 but who knows, maybe someone will need them.
794 <sect3>EnterTurbo, ExitTurbo, PurgeTurbo
796 <tt/void EnterTurbo (void)/
798 <tt/void ExitTurbo (void)/
800 <tt/void PurgeTurbo (void)/
802 These functions are the interface to the GEOS TurboDos feature which makes slow Commodore drives a bit
803 more usable. <tt/EnterTurbo/ enables TurboDos unless it is already enabled. If not, then you will
804 have to wait a bit to transfer the TurboDos code into disk drive RAM. <tt/ExitTurbo/ disables TurboDos.
805 This is useful for sending some DOS commands to a drive e.g. for formatting. Note that before any
806 interaction with the Kernal in ROM you have to call <tt/InitForIO/. You don't have to worry about speed.
807 <tt/EnterTurbo/ will only enable TurboDos (no code transfer) if TurboDos was disabled with
808 <tt/ExitTurbo/. <tt/PurgeTurbo/ acts differently from <tt/ExitTurbo/ - it not only disables TurboDos,
809 but also removes it from drive RAM (not quite true, but it works like that). After using
810 <tt/PurgeTurbo/ the next call to <tt/EnterTurbo/ will reload drive RAM.
812 <sect3>ChangeDiskDevice
814 <tt/char ChangeDiskDevice (char newDevice)/
816 This function changes the device number of the current device (in fact drives only) to the given one. It is
817 usable for swapping drives. There's no check if the given <tt/newDevice/ already exist, so if you want
818 to change the logical number of drive 8 to 9 and you already have a drive number 9 then GEOS will probably
819 hang on disk access. Use safe, large numbers. Note that the safe IEC range is 8-30.
821 <sect2>Disk Initialization
823 GEOS has two functions for initialization ('logging in' as they say on CP/M) of a disk.
826 <tt/char OpenDisk (void)/
828 This function initializes everything for a new disk. It loads and enables TurboDos if needed.
829 Then the disk is initialized with <tt/NewDisk/. Next, <tt/GetDirHead/ initializes <tt/curDirHead/.
830 Disk names are compared and if they differ then the disk cache on REU is cleared. Finally the format is
831 checked with <tt/ChkDkGEOS/ and the disk name is updated in the internal tables.
835 <tt/char NewDisk (void)/
837 This function is similar to the DOS command I. It clears the REU cache and enables TurboDos if needed.
841 This section covers the GEOS file interface.
843 <sect2>Directory handling
845 The functions described here are common for SEQ and VLIR structures.
847 <sect3>Get1stDirEntry and GetNxtDirEntry
849 <tt/struct filehandle *Get1stDirEntry (void)/
851 <tt/struct filehandle *GetNxtDirEntry (void)/
853 These two functions are best suited for scanning the whole directory for particular files. Note that
854 the returned filehandles describe all file slots in the directory - even those with deleted files.
855 The return value can be obtained by casting both sides to <tt/unsigned/ - as in the <tt/SetNextFree/
856 function or read directly after a call to those two functions from <tt/r5/. The current sector number
857 is in <tt/r1/ and the sector data itself is in <tt/diskBlkBuf/.
861 <tt/char FindFile (char *fName)/
863 This function scans the whole directory for the given filename. It returns either 0 (success) or 5
864 (FILE_NOT_FOUND, defined in <tt/gdisk.h/) or any other fatal disk read error. After a successful
865 <tt/FindFile/ you will have <tt/struct filehandle/ at <tt/dirEntryBuf/ filled with the file's data and
866 other registers set as described in <tt/GetNxtDirEntry/.
870 <tt/char FindFTypes (char *buffer, char fType, char fMaxNum, char *classTxt)/
872 This function scans the directory and fills a table at <tt/buffer/ with <tt/char [17]/ entries.
873 <tt/fType/ is the GEOS type of the searched files and <tt/classTxt/ is a string for the Class field in the file
874 header. Class matches if the given string is equal or shorter than that found in the file's header block.
875 If you want just to find all files with the given GEOS type you should pass an empty string or <tt/NULL/ as
876 <tt/classTxt/. Be warned that for searching <tt/NON_GEOS/ files you must pass <tt/NULL/ as <tt/classTxt/.
877 <tt/fMaxNum/ is the maximal number of files to find, thus the <tt/buffer/ must provide an area of size
878 equal to <tt/17 * fMaxNum/. This function returns the number of found files, ranging from 0 to number
879 passed as <tt/fMaxNum/. The return value can be also restored from <tt/r7H/.
883 <tt/char DeleteFile (char *fName)/
885 This function deletes a file by its name. It works for SEQ and VLIR files.
889 <tt/char RenameFile (char *oldName, char *newName)/
891 I think it is obvious...
895 <tt/char GetFHdrInfo (struct filehandle *myFile)/
897 This function loads the file header into the <tt/fileHeader/ buffer. Using after e.g. <tt/FindFile/
898 you can pass the address of <tt/dirEntryBuf/.
900 <sect2>Common and SEQ structure
902 Functions described here are common for SEQ and VLIR structures because the arguments passed are the
903 starting track and sector which may point either to the start of a chain for VLIR or the data for SEQ.
907 <tt/char __fastcall__ GetFile(char flag, const char *fname, const char *loadaddr, const char *datadname, const char *datafname)/
909 This routine loads and runs a given file <tt/fname/. The file must be one of following types:
910 <tt/SYSTEM, DESK_ACC, APPLICATION, APPL_DATA, PRINTER,/ or <tt/INPUT_DEVICE/. The execution
911 address is taken from the file header. If it is zero, then the file is only loaded. Only the first chain
912 from VLIR files is loaded. If <tt/flag/ has bit 0 set then the load address is taken from <tt/loadaddr/
913 and not from the file header. In this case <tt/APPLICATION/ files will be only loaded, not executed.
914 This does not apply to <tt/DESK_ACC/. If either bit 6 or 7 of <tt/flag/ are set, then 16 bytes from
915 <tt/datadname/ are copied to <tt/dataDiskName/ and 16 bytes from <tt/datafname/ go to <tt/dataFileName/
916 thus becoming parameters for the new application. Pass <tt/NULL/ for 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 the next byte from a file. Before the first call to it you must load <tt/r5/
930 with <tt/NULL/, <tt/r4/ with the sector buffer address and <tt/r1/ with the 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 The returned value is valid only if there was no error. The 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 the
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 if VLIR of SEQ
944 structure. All you need to do is to place the data in the 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 the 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 a link to a nonexistent next sector are replaced by a
951 pointer to the DOS filename of the file.
953 When saving sequential files the 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 the 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 the sector numbers for a 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 is information about VLIR files (later called RecordFiles) and functions.
973 A VLIR structure file 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 a common name - the VLIR file name and
975 an own number. Each record pointed to by its number is described by the 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 the starting track and sector of
980 In GEOS there can be only one file opened at a time. Upon opening a VLIR file some information
981 about it is copied into memory. You can retrieve the records table at <tt/fileTrScTab/ (table of
982 128 <tt/struct tr_se/) and from <tt/VLIRInfo/ (<tt/struct VLIR_info/.
983 E.g. the 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 a given file. An error is returned if the 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 a call to <tt/CloseRecordFile/ so don't modify it.
992 You should call <tt/PointRecord/ before trying to do something with the 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 the <tt/VLIRInfo.fileWritten/ flag and if it is set, then <tt/curDirHead/ is
1005 updated along with size and date stamps in the 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 the given record in <tt/r1/. Note that the data may not be valid (if the 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 the 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 the 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 the table one place forward (contents of <tt/VLIRInfo.curRecord/ after a 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 the currently pointed record into or from
1055 <sect1>Memory and Strings
1057 The functions covered in this section are common for the whole C world - copying memory parts and
1058 strings is one of the main computer tasks. GEOS also has an interface to do this. These functions
1059 are replacements for those like <tt/memset, memcpy, strcpy/ etc. from standard libraries.
1060 If you are dealing with short strings (up to 255 characters) you should use these functions
1061 instead of standard ones, e.g. <tt/CopyString/ instead of <tt/strcpy/. It will work faster.
1063 However some of them have slightly different calling conventions (order of arguments to be specific),
1064 so please check their syntax here before a direct replacement.
1066 Please note that the memory areas described here as <em/strings/ are up to 255 characters (without
1067 counting the terminating <tt/NULL/), and <em/regions/ can cover the whole 64K of memory.
1071 <tt/void CopyString (char *dest, char *src)/
1073 This function copies the string from <tt/src/ to <tt/dest/, until it reaches <tt/NULL/. The <tt/NULL/
1078 <tt/char CmpString (char *s1, char *s2)/
1080 This function compares the strings <tt/s1/ to <tt/s2/ for equality - this is case sensitive, and both
1081 strings have to have the same length. It returns either <tt/true/ (non-zero) or <tt/false/ (zero).
1083 <sect2>CopyFString and CmpFString
1085 <tt/void CopyFString (char length, char *dest, char *src)/
1087 <tt/char CmpFString (char length, char *s1, char *s2)/
1089 These two are similar to <tt/CopyString/ and <tt/CmpString/ except the fact, that you provide
1090 the length of the copied or compared strings. The strings can also contain several <tt/NULL/
1091 characters - they are not treated as delimiters.
1095 <tt/unsigned CRC (char *src, unsigned length)/
1097 This function calculates the CRC checksum for the given memory range. I don't know if it is
1098 compatible with standard CRC routines.
1100 <sect2>FillRam and ClearRam
1102 <tt/void *FillRam (char *dest, char value, unsigned length)/
1104 <tt/void *ClearRam (char *dest, unsigned length)/
1106 Both functions are filling the given memory range. <tt/ClearRam/ fills with <tt/0s/, while
1107 <tt/FillRam/ uses the given <tt/value/. Be warned that these functions destroy <tt/r0, r1 and
1108 r2L/ registers. The functions are aliases for <tt/memset/ and <tt/bzero/, respectively.
1112 <tt/void *MoveData (char *dest, char *src, unsigned length)/
1114 This functions copies one memory region to another. There are checks for an overlap and the
1115 non-destructive method is chosen. Be warned that this function destroys contents of the
1116 <tt/r0, r1 and r2/ registers. This function is an alias for <tt/memcpy/.
1120 <tt/void InitRam (char *table)/
1122 This function allows to initialize multiple memory locations with single bytes or strings.
1123 This is done with a <tt/table/ where everything is defined. See the structures chapter for a description of
1124 <tt/InitRam's/ command string.
1126 <sect2>StashRAM, FetchRAM, SwapRAM, and VerifyRAM
1128 <tt/void StashRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1130 <tt/void FetchRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1132 <tt/void SwapRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1134 <tt/ char VerifyRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1136 These functions are the interface to a REU - Ram Expansion Unit. I think that they are self-explanatory.
1137 You can check for REU presence by taking the value of <tt/ramExpSize/. You have to do it before
1138 using any of these functions.
1140 <sect1>Processes and Multitasking
1142 Weird? Not at all. GEOS has some limited multitasking ability. You can set up a chain of functions
1143 called in specified intervals and you can put the main program to sleep without disturbing other
1144 tasks and making the user interface unresponsive.
1146 <sect2>InitProcesses
1148 <tt/void InitProcesses (char number, struct process *processTab)/
1150 This is the main initialization routine. After calling it processes are set up, but not
1151 enabled. The parameters for <tt/InitProcesses/ are:
1153 <item><tt/number/ - number of processes
1154 <item><tt/processTab/ - a table of <tt/struct process/, with size equal to <tt/number/
1157 A single task is described by an entry in <tt/processTab/, it contains two values - a <tt/pointer/ to
1158 the task function and a number of <tt/jiffies/ which describe the delay between calls to task. On PAL
1159 systems there are 50 jiffies per second, while on NTSC there are 60.
1161 The maximum number of tasks is 20. Be warned that GEOS doesn't check if parameters are valid and
1162 if <tt/processTab/ would be too large it would overwrite existing data in GEOS space.
1164 There's one important thing - the last entry in <tt/processTab/ has to be <tt/NULL,NULL/, so the
1165 maximum size of <tt/processTab/ is equal to 21.
1167 See the description of <tt/process/ structure for a more detailed discussion on this.
1169 <sect2>RestartProcess and EnableProcess
1171 <tt/void RestartProcess (char processNumber)/
1173 <tt/void EnableProcess (char processNumber)/
1175 These two functions start the task counter. <tt/RestartProcess/ should be called for each process
1176 after <tt/InitProcesses/, because it resets all flags and counters and it starts the counters.
1178 <tt/RestartProcess/ enables the counters and sets their initial value to that given in <tt/processTab/.
1180 <tt/EnableProcess/ forces the given process to execute by simulating the timer expiring.
1182 <sect2>BlockProcess and UnblockProcess
1184 <tt/void BlockProcess (char processNumber)/
1186 <tt/void UnblockProcess (char processNumber)/
1188 <tt/BlockProcess/ disables the execution of the given process, but this does not disable the timers.
1189 It means that if you call <tt/UnblockProcess/ before the timer runs out, the process will be executed.
1191 <tt/UnblockProcess/ does the opposite.
1193 <sect2>FreezeProcess and UnfreezeProcess
1195 <tt/void FreezeProcess (char processNumber)/
1197 <tt/void UnfreezeProcess (char processNumber)/
1199 <tt/FreezeProcess/ disables timer for given process. <tt/UnfreezeProcess/ does the opposite.
1200 This is not equal to <tt/RestartProcess/ as timers are not reloaded with initial value.
1204 <tt/void Sleep (unsigned jiffies)/
1206 This function is a multitasking sleep - the program is halted, but it doesn't block other functions
1207 e.g. callbacks from menus and icons.
1208 The only argument here is the number of jiffies to wait until the app will wake up. It depends on the
1209 video mode (PAL or NTSC) how many jiffies there are per second (50 or 60, respectively).
1210 If you don't want to worry about it and need only full second resolution, call the standard
1211 <tt/sleep/ function from <tt/unistd.h/.
1213 <sect1>System Functions
1217 <tt/void FirstInit (void)/
1219 This function initializes some GEOS variables and mouse parameters. This is called on GEOS boot
1220 up. You shouldn't use this unless you know what you are doing.
1222 <sect2>InitForIO and DoneWithIO
1224 <tt/void InitForIO (void)/
1226 <tt/void DoneWithIO (void)/
1228 These functions are called by some disk routines. You should call them only if you want to
1229 do something with IO registers or call one of the Kernal ROM routines. Note that this is rather an
1230 expensive way of turning off IRQs and enabling IO.
1234 <tt/void MainLoop (void)/
1236 Returns control to the system. Any code between call to <tt/MainLoop/ and the end of current
1237 function will never be executed. When in <tt/MainLoop/ the system waits for your action - using
1238 icons, keyboard or menus to force some specific action from the program. You have to define
1239 proper handlers before that.
1243 <tt/void EnterDeskTop (void)/
1245 This is an alias for <tt/exit(0)/ so you will never burn yourself. Anyway, you should not
1246 use it. Always use <tt/exit()/ instead. Library destructors and functions registered with
1247 <tt/atexit()/ are called.
1251 <tt/void ToBASIC (void)/
1253 This one is another way of terminating an application - forcing GEOS to shutdown and exit to BASIC.
1254 I was considering whether to include it or not, but maybe someone will need it - which I doubt.
1256 <em/WARNING:/ library destructors and functions registered with <tt/atexit()/ will not be called
1257 so it is quite unsafe way to terminate your program.
1261 <tt/void Panic (void)/
1263 This calls system's <tt/Panic/ handler - it shows a dialog box with the message
1265 System error at:xxxx
1267 where <tt/xxxx/ is last known execution address (caller). By default this is bound to the <tt/BRK/
1268 instruction, but it might be usable in debugging as kind of <tt/assert/. (Note that <tt/assert/
1269 is available as a separate function and will give you more information than that).
1271 The system is halted after a call to <tt/Panic/ which means that library destructors will not be
1272 called and some data may be lost (no wonder you're panicking).
1276 <tt/void CallRoutine (void *myFunct)/
1278 This is a system caller routine. You need to provide a pointer to a function and it will be immediately
1279 called, unless the pointer is equal to <tt/NULL/. This is the main functionality of this function -
1280 you don't need to check if the pointer is valid.
1282 <sect2>GetSerialNumber
1284 <tt/unsigned GetSerialNumber (void)/
1286 This function returns the serial number of the system. It might be used for copy-protection.
1287 However, please remember that Free Software is a true power and you are using it right now.
1291 <tt/char GetRandom (void)/
1293 This function returns a random number. It can be also read from <tt/random/ e.g.
1297 but by calling this function you are sure that the results will be always different.
1298 <tt/random/ is updated once a frame (50Hz PAL) and on every call to <tt/GetRandom/.
1300 Note that this is not the same as the <tt/rand/ function from the standard library. <tt/GetRandom/
1301 will give you unpredictable results (if IRQs occur between calls to it) while
1302 <tt/rand/ conforms to the standard and for a given seed (<tt/srand/) always returns with the
1303 same sequence of values.
1307 <tt/void SetDevice (char device)/
1309 This function sets the current device to the given. It might be used together with <tt/InitForIO/,
1310 <tt/DoneWithIO/ and some Kernal routines. Unless the new device is a disk drive this only sets
1311 new value in <tt/curDevice/, in the other case new disk driver is loaded from REU or internal RAM.
1315 <tt/char get_ostype (void)/
1317 This function returns the GEOS Kernal version combined (by logical OR) with the machine type. Read
1318 <tt/gsys.h/ for definitions of the returned values.
1322 <tt/char get_tv (void)/
1324 This function returns the PAL/NTSC flag combined (by logical OR) with the 40/80 columns flag. This is
1325 not the best way to check if the screen has 40 or 80 columns since a PAL/NTSC check is always
1326 performed and it can take as long as a full raster frame. If you just want to know if the
1327 screen has 40 or 80 columns use the expression <tt/graphMode & 0x80/ which returns <tt/0/ for
1328 40 columns and <tt/0x80/ for 80 columns. Remember that this value can be changed during
1329 runtime. It is unclear if this will work for GEOS 64 so you probably do not want to test
1330 anything if not running under GEOS128. Use <tt/get_ostype/ to check it. Read <tt/gsys.h/ for
1331 definitions of the returned values.
1333 <sect>Library Structures
1335 To simplify usage and optimize passing parameters to functions I have declared several structures
1336 which describe the most common objects. Some of these structures are bound to static addresses in
1337 the GEOS data space (<tt/$8000-$8fff/), so you can use their fields directly in an optimized way.
1338 Please see <tt/gsym.h/ to find them. All structures are defined in <tt/gstruct.h/ and you may
1339 find also some comments there.
1341 <sect1>Graphics Structures
1345 A simple structure describing a point on the screen.
1349 This structure describes a font in one pointsize. There is the current font - <tt/struct fontdesc/
1350 bound to <tt/curFontDesc/. You can also force GEOS to use your own fonts by calling
1351 <tt/LoadCharSet/. You just need to open a VLIR font file and load one record - one pointsize -
1352 somewhere. At the start of this area you already have all data for <tt/fontdesc/ so you can
1353 pass a pointer to the load address of that pointsize to <tt/LoadCharSet/. (Note that although
1354 it has 'Load' in the name, that function loads only GEOS internal data structures, not data
1359 This widely used structure holds the description of a region of the screen. It describes the top-left and
1360 bottom-right corners of a window.
1364 Maybe the name isn't the best - it has nothing with <tt/DoIcons/ but with bitmap functions -
1365 <tt/BitmapUp/ for example. This structure holds the parameters needed to properly decode and show
1366 a bitmap on the screen. The bitmap has to be encoded - if you have some non-GEOS bitmaps simply
1367 convert them to Photo Scraps - this is the format used by all GEOS bitmap functions - <tt/DoIcons/
1372 These structures describe click boxes (icons) that can be placed on screen or in a dialog box.
1376 This is the definition of a single click box. Please see <tt/gstruct.h/ for a description of its fields.
1380 This is the toplevel description of icons to be placed and enabled on the screen. This structure
1381 has the following fields:
1383 <item><tt/char number/ - total number of icons declared here
1384 <item><tt/struct pixel mousepos/ - after finishing <tt/DoIcons/ the mouse pointer will be placed in
1385 this point allowing you to have a hint for the user what the default action is
1386 <item><tt/struct icondef tab[&rsqb/ - this table of size equal to <tt/icontab.number/ contains
1387 descriptions for all icons
1390 <sect1>File and Disk
1394 This simple structure holds the track and sector number of something. Do not expect the track to be
1395 in range 1-35, as GEOS can support many various and weird devices. For example my C128 256K
1396 expansion is utilized as RAMDisk with a layout of 4 tracks of 128 sectors each. However assuming that
1397 a track number equal to 0 is illegal might be wise.
1401 This is a placeholder for a file datestamp. This structure is also present in <tt/struct filehandle/.
1402 GEOS is not Y2K compliant, so if the current file has in <tt/filehandle.date.year/ a value less than 86
1403 you can safely assume that it is e.g. 2004 and not 1904.
1407 This is the main file descriptor. It is either an entry in the directory (returned from file functions)
1408 or its copy in <tt/dirEntryBuf/. This is optimized so you can safely get to the file's year e.g.
1409 by testing <tt/dirEntryBuf.date.year/ - it will be compiled to simple <tt/LDA, STA/.
1413 This structure holds the fileheader description. You can load a file's header into the <tt/fileHeader/
1414 fixed area using <tt/GetFHdrInfo/. (note that <tt/fileHeader/ is a place in memory while
1415 <tt/fileheader/ is a structure).
1416 You will also need your own fileheader for <tt/SaveFile/.
1418 <sect1>System Structures
1422 This structure is defined only for <tt/system_date/. It is slightly different from <tt/f_date/
1423 so I prepared this one. You can e.g. get or set the current time using <tt/system_date.s_hour/ and
1424 <tt/system_date.s_minute/. Accesses to these will be optimized to simple <tt/LDA/ and <tt/STA/
1429 You should declare a table of that type to prepare data for <tt/InitProcesses/. The maximum number
1430 of processes is 20, and the last entry has to be equal to <tt/{NULL,NULL}/, so this table may hold
1431 only 21 entries. The first member of this structure (<tt/pointer/) holds the pointer to the called
1432 function (void returning void), you will probably have to cast that pointer into <tt/unsigned int/.
1433 The second field <tt/jiffies/ holds the amount of time between calls to that function.
1434 On PAL systems there are 50 jiffies per second, while NTSC have 60 of them.
1436 <sect1>A few things in detail...
1438 GEOSLib uses cc65 non-ANSI extensions to easily initialize data in memory. This is done with a
1439 kind of array of unspecified length and unspecified type. Here is how it works:
1441 void example = {
1442 (char)3, (unsigned)3, (char)0 };
1444 Which will be compiled to following string of bytes:
1451 As you see this way it is possible to define data of any type in any order. You must remember to
1452 cast each member to proper type.
1454 <sect2>DoMenu structure
1456 <tt/DoMenu/ is responsible for everything concerned with menu processing. Many, many GEOS programs
1457 are just initializing the screen and menu and returning to <tt/MainLoop/. In GEOSLib it is the same as
1458 returning from <tt/main/ function without using <tt/exit(0)/.
1460 A menu is described by two types of data - menu descriptors and menu items. A descriptor contains
1461 information about the following menu items, and items contain names of entries and either
1462 pointers to functions to execute or, in case of nested menus, pointers to submenu descriptors.
1463 Note that submenu descriptor can be top-level descriptor, there's no difference in structure,
1464 just in the content.
1466 Here is how a single descriptor looks like:
1468 void myMenu = {
1469 (char)top, (char)bottom, // this is the size of the menubox
1470 (unsigned)left, (unsigned)right, // counting all items in the current descriptor
1471 (char)number_of_items | type_of_menu, // number of following items ORed with
1472 // type of this menu, it can be either
1473 // HORIZONTAL or VERTICAL if you will have also bit 6 set then menu won't be closed
1474 // after moving mouse pointer outside the menubox. You can have at most 31 items.
1476 This is followed by <tt/number_of_items/ of following item description.
1479 "menuitemname", (char)item_type, (unsigned)pointer,
1480 "nextitemname", (char)item_type, (unsigned)pointer,
1482 "lastitemname", (char)item_type, (unsigned)pointer };
1483 // Note that there isn't ending <tt/NULL/ or something like that.
1485 <tt/pointer/ is a pointer to something, what it points for depends from <tt/item_type/. This one
1486 can have following values:
1488 <tt/MENU_ACTION/ - a function pointed by <tt/pointer/ will be called after clicking on the menu item
1490 <tt/SUB_MENU/ - <tt/pointer/ points to next menu descriptor - a submenu
1492 Both of them can be ORed with <tt/DYN_SUB_MENU/ and then the <tt/pointer/ points to a function
1493 which will return in <tt/r0/ the needed pointer (to function to execute or a submenu).
1495 For creating nested menus (you can have at most 8 levels of submenus) you need to declare such
1496 a structure for each submenu and top level menu.
1498 <sect2>DoDlgBox command string
1500 <tt/DoDlgBox/ is together with <tt/DoMenu/ one of the most powerful routines in GEOS. It is
1501 responsible for creating dialog boxes, that is windows which task is to interact with the user.
1502 The format of the command string is following:
1504 (window size and position)
1505 (commands and parameters)
1508 There is a custom type defined for the command string: <tt/dlgBoxStr/.
1510 <sect3>Size and position
1512 The first element can be specified in two ways - by using the default size and position or specifying
1513 your own. The first case results in
1515 const dlgBoxStr example = {
1516 DB_DEFPOS (pattern_of_shadow),
1520 And the own size and position would be:
1522 const dlgBoxStr example = {
1523 DB_SETPOS (pattern, top, bottom, left, right)
1530 The next element of the <tt/DoDlgBox/ command string are the commands themselves. The first six commands are
1531 default icons and the number of the selected icon will be returned from window processor. The icons are
1532 <tt/OK, CANCEL, YES, NO, OPEN/, and <tt/DISK/. You can use predefined macros for using them, e.g.:
1535 DB_ICON(OK, DBI_X_0, DBI_Y_0),
1538 Note that the position is counted from top left corner of window, not entire screen and that the 'x'
1539 position is counted in cards (8-pixel) and not in pixels. This is also true for all following commands.
1540 <tt/DBI_X_0/ and <tt/DBI_Y_0/ are predefined (see <tt/gdlgbox.h/ for more), the default positions
1541 which will cause icons to appear on a default window exactly where you would expect them.
1543 <tt/DB_TXTSTR (x, y, text)/ will cause to show the given text in the window.
1545 <tt/DB_VARSTR (x, y, ptr)/ works as above, but here you are passing a pointer to a zero page location
1546 where the address of the text is stored. This is useful for information windows where only the text content
1547 is variable. Consider following:
1551 r15=(unsigned)text; // in code just before call to DoDlgBox
1553 DB_VARSTR (TXT_LN_X, TXT_LN_1_Y, &r15),
1556 will cause the word ``foo'' to appear in the window, but you may store the pointer to any text in
1557 <tt/r15/ (in this case) before the call to DoDlgBox.
1559 <tt/DB_GETSTR(x, y, ptr, length)/ - will add a input-from-keyboard feature. <tt/ptr/ works as in the
1560 previous example and points to the location where the text is to be stored. Note that the contents of this
1561 location will be shown upon creating the window. <tt/length/ is the maximum number of characters to input.
1563 <tt/DB_SYSOPV(ptr)/ - this sets <tt/otherPressVec/ to the given pointer. It is called on every keypress.
1565 <tt/DB_GRPHSTR(ptr)/ - the data for this command is a pointer for <tt/GraphicsString/ commands.
1567 <tt/DB_GETFILES(x, y)/ - for a standard window you should pass 4 for both x and y. This function
1568 draws a file selection box and searches the current drive for files. Before the call to <tt/DoDlgBox/ you
1569 must load <tt/r7L/ with the GEOS filetype of searched files and <tt/r10/ with the class text. In <tt/r5/
1570 you have to load a pointer to a <tt/char[17]/ where the selected filename will be copied. It works
1571 like <tt/FindFTypes/ but is limited to first 16 files.
1573 <tt/DB_OPVEC(ptr)/ - this sets a new pointer for the button press function, if you pass
1574 <tt/RstrFrmDialogue/ here you will cause the window to close after pressing mouse button.
1576 <tt/DB_USRICON(x, y, ptr)/ - places a single user icon (click box) on the window, <tt/ptr/ points at a
1577 <tt/struct icondef/ but fields <tt/x/ and <tt/y/ are not used here. You can have at most 8 click
1578 boxes in a window, this is an internal limit of the GEOS Kernal.
1580 <tt/DB_USRROUT(ptr)/ - this command causes to immediately call the user routine pointed by <tt/ptr/.
1582 <sect2>GraphicsString command string
1584 <tt/GraphicsString/ is a very powerful routine to initialize the whole screen at once. There are
1585 predefined macros for all commands, names are self-explanatory, see them in <tt/ggraph.h/. The last
1586 command has to be <tt/GSTR_END/. There is a custom type defined for the command string: <tt/graphicStr/.
1588 Here is an example for clearing the screen:
1590 const graphicStr example = {
1593 RECTANGLETO(319,199)
1597 <sect2>InitRam table
1599 This type of data is used to initialize one or more bytes in different locations at once. The format is
1602 void example = {
1603 (unsigned)address_to_store_values_at,
1604 (char)number_of_bytes_that_follow,
1605 (char)data,(char)data (...)
1606 // more such definitions
1607 (unsigned)NULL // address of 0 ends the table
1611 <sect2>Intercepting system vectors
1613 It is possible to intercept events and hook into the GEOS Kernal using vectors. Here is a little example:
1615 void_func oldVector;
1617 void NewVectorHandler(void) {
1618 // do something and at the end call the old vector routine
1622 void hook_into_system(void) {
1623 oldVector = mouseVector;
1624 mouseVector = NewVectorHandler;
1627 void remove_hook(void) {
1628 mouseVector = oldVector;
1632 In your <tt/main/ function you should call <tt/hook_into_system()/ but <em/after/ all calls to the GEOS
1633 Kernal (like <tt/DoMenu/, <tt/DoIcons/, etc.) - right before passing control to the <tt/MainLoop()/.
1634 Be warned that vectors are most likely to be changed by the GEOS Kernal also via other functions (like
1635 <tt/GotoFirstMenu/, <tt/DoDlgBox/ and its derivatives etc.). It depends on what Kernal functions
1636 you use and which vectors you altered. Unfortunately there is no exact list for GEOS 2.0, a complete
1637 list for GEOS 1.x can be found in A. Boyce's Programmers' Reference Guide mentioned before. Most of the
1638 information contained there should be still valid for GEOS 2.0. When calling a function that restores
1639 the vector you should add a <tt/hook_into_system()/ call right after it.
1641 It is critical to restore old vector values before exiting the program. If you have more than one
1642 place where you call <tt/exit()/ then it might be worth to register <tt/remove_hook/ function to
1643 be called upon exiting with <tt/atexit(&remove_hook);/ call. This way you will ensure that
1644 such destructor will be always called.
1646 That little example above intercepts <tt/mouseVector/. The <tt/NewVectorHandler/ function will be
1647 called every time the mouse button changes status. Other important vectors you should know about
1650 <item><tt/appMain/ - this is called from within the <tt/MainLoop/ system loop
1651 <item><tt/keyVector/ - called whenever a keypress occurs
1652 <item><tt/intTopVector/ - called at the start of the IRQ routine
1653 <item><tt/intBotVector/ - called at the end of the IRQ routine