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, 2005
11 This is the documentation of cc65's GEOSLib, but information contained here may be also
12 useful for writing 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 the C64 and C128. They have their GUI too -
23 the 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 a 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 the 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 write your program. If you don't need long strings simply use functions from the Kernal,
35 the 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 does fit in 8x8 cell, so output with
42 default BSW font, which is has 9 points, might be a bit messy. There is no color support in
43 GEOS 2.0 so color functions are disabled. Both 40 and 80 column modes are supported
44 and automatically detected.
46 <tt/tgi/ - TGI driver for GEOS that supports both 40 and 80 column modes but mode can not be
47 changed between <tt/tgi_init/ and <tt/tgi_done/.
49 <tt/joy/ - JOY driver for GEOS that supports only joystick, not current pointing device.
51 It is safe to use these standard includes and their contents:
52 <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/
54 For <tt/time.h/ functions <tt/systime()/ and <tt/clock()/ note that the resolution is one second.
56 Functions from the headers above are either standard C library functions or cc65-specific, in
57 either case they are not GEOS specific and so they are not described here.
59 I am an assembler programmer and GEOSLib was designed in such way that cc65 could emit the best
60 available code (well, the best as for machine :-). Many of the <tt/void foo (void)/ functions are
61 just raw calls to the Kernal (assembled just as <tt/jsr _foo/), look in <tt/gsym.h/, where you
62 can find many definitions of standard GEOS locations. Access to these addresses is optimized by
63 cc65 to simple <tt/lda/ and <tt/sta/. Don't be afraid to use C syntax.
67 You don't need a C64 or C128 for development. The only hardware requirement is a PC capable of
68 running cc65. You do however need C64 or C128 emulator and GEOS disk images (.d64) to test your
73 <item><em/cc65/ Excellent package containing a C crosscompiler, a crossassembler and a linker, you
74 can get it from: <htmlurl url="http://www.cc65.org/"
75 name="http://www.cc65.org/">
76 <item><em/VICE/ This is a portable C64, C128 and few other Commodore computers emulator, you
77 can obtain it from: <htmlurl url="http://www.viceteam.org/"
78 name="http://www.viceteam.org/">. The VICE package contains the
79 c1541 program that is able to convert/unconvert GEOS files to disk images.
80 <item><em/The Star Commander/ This tool is only for DOS. You will need it for transferring
81 object files from a PC to a 1541. There's also one important ability of this
82 tool - it automatically un-converts .cvt files into GEOS native format on
83 disk image files. Check out: <htmlurl url="http://sta.c64.org/sc.html"
84 name="http://sta.c64.org/sc.html">
85 <item><em/cbm4linux/ A Linux kernel module that allows for communication with a 1541 and
86 other Commodore IEC bus drives. It can be a replacement for Star Commander if
87 you only want to transfer files to a disk and unconvert using GEOS program for
88 this purpose. Check out: <htmlurl url="http://www.lb.shuttle.de/puffin/cbm4linux/"
89 name="http://www.lb.shuttle.de/puffin/cbm4linux">
92 VICE and cc65 are portable - they run on variety of platforms - DOS, Win32 and UNIX. GEOSLib only
95 <em/Update:/ starting from v2.5.0 GEOSLib is a part of the cc65 package as its GEOS support library.
99 I want to thank Uz for his cc65 package, Alexander Boyce for his excellent GEOS Programmer's
100 Reference Guide and BSW for GEOS.
102 GEOSLib is covered by the same license as cc65. You can find the whole text
103 among documentation. I would really appreciate if you would like to send me
104 your comments, suggestions, questions, changes, bug reports etc. I will also
105 appreciate if you will just give me a sign that you are using GEOSLib - not
106 especially something big and important, mail me even if you are just playing
109 You can send postcards with hellos to:
111 Maciej Witkowiak, ul. Slowackiego 6/57, 77-400 ZLOTOW
115 e-mail: <tt/ytm@elysium.pl/
117 <sect>What do you have and what to do with it?
119 This chapter describes some rules you ought to obey, and how to use GEOSLib.
123 Apart from this file, which merely describes only standard GEOS library
124 functions, you should read the <tt/grc65/ (GEOS resource compiler) documentation.
125 There is information about necessary resource files (each GEOS application
126 needs at least one) and the build process - what should be done and in what
127 order. Please also read the cc65 documentation on how to compile C, assembler
128 and link everything together.
130 All in all, you just need to place
132 #include <geos.h>
134 at the top of your source.
136 As a general rule read the sources of the example programs and read the headers.
137 These are the most reliable sources of knowledge ;-). You will also find there
138 many C macros representing various arguments passed to the functions. Please use
139 them. You will find your sources easier to understand, and it will be easier
142 All types used in GEOSLib are <tt/unsigned/.
144 Screen coordinates are given in pixels unless stated differently.
146 <sect1>Notes on style
148 Contrary to a typical GEOS assembly program which has a main function called after loading that
149 setups the screen, menus, icons etc. exiting from the <tt/main/ function in C is equivalent to
150 calling <tt/exit()/. These two are the only safe methods of terminating applications. DO NOT
151 USE <tt/EnterDeskTop/! Your data may be lost as library destructors and functions registered
152 with <tt/atexit/ are not called.
154 For GEOS GUI applications the recommended program structure is to have everything initialized
155 in the <tt/main/ function and at the end of it a call to the <tt/MainLoop()/ function. WARNING! This
156 function never returns, any code between <tt/MainLoop();/ and the end of <tt/main/ will not
157 be executed. You have to call <tt/exit()/ explicitly somewhere in your code (e.g. in a menu
158 handler or via DialogBox action).
160 Whenever possible use definitions from <tt/gsym.h/. The resulting code is translated by cc65 into
161 series of <tt/lda/ and <tt/sta/, so you can't do it better :-).
163 Don't hesitate to use library functions. Everything was written with size and speed in mind. In
164 fact many calls are just redirections to the GEOS Kernal which results in a simple <tt/jsr/.
166 The <tt/main/ function receives the standard <tt/argc/ and <tt/argv/ parameters. There are
167 always either 1 or 3 parameters. The DOS application name is always set as <tt/argv[0]/.
168 If present, <tt/argv[1]/ and <tt/argv[2]/ will be set to the data filename and data diskname (it only
169 works if the user double-clicks on a data file associated with your application). Note that it is up
170 to your application to determine which of the available (up to four) disk drives has the disk
171 with given diskname inside. If this fails your program should ask to insert the proper disk into
172 one of available drives.
174 You might wonder why I have chosen a sometimes weird order of arguments in functions. I just
175 wanted to avoid unnecessary pushing and popping of arguments from the stack because cc65 can pass a single
176 <tt/unsigned int/ through CPU registers.
178 Do not try to compile in strict ANSI mode. The library uses cc65 extensions which are not available in
181 It is possible to use dynamically loaded modules, three such modules are provided:
182 A GEOS TGI driver, a GEOS EMD driver (for VDC extended memory) and a GEOS JOY driver.
183 Just make sure that their filenames appear UPPERCASE in DeskTop. There are no more special
184 recommendations, read the cc65 documentation about modules and the demo programs source code.
186 <sect>Library Functions
188 Functions here are sorted more or less in the way they appear in the header files. This way I am able
189 to keep functions covering similar tasks near each other. All function names are identical to those
190 from the <tt/geosSym/ file provided with the GeoProgrammer package. Only my extensions to <tt/geosSym/
191 are covered by new names, but I tried to keep them in the naming convention.
195 This section covers the drawing package of GEOS along with text output routines.
199 <tt/void SetPattern (char pattern)/
201 This function sets the current pattern to the given. There are 32 different patterns in GEOS. You can
202 see them together in the filling box in GeoPaint.
204 <sect2>GraphicsString
206 <tt/void GraphicsString (char *myGString)/
208 One of the more powerfull routines of GEOS. This function calls other graphic functions depending
209 on the given command string. See the structures chapter for a more detailed description.
211 <sect2>Rectangle functions
213 Parameters to those functions are grouped in the <tt/struct window drawWindow/. To speed up things and
214 reduce overhead this structure is bound to zero page locations, where all rectangle functions
215 expect their parameters. You can modify the data directly (e.g. <tt/drawWindow.top=10/) or via the
216 <tt/InitDrawWindow/ function. Contents of <tt/drawWindow/ are guaranteed not to change when only
217 using graphics functions. In other cases you should keep your data in separate <tt/struct window/
218 and use <tt/InitDrawWindow/ before the first call to one of the rectangle functions.
220 <sect3>InitDrawWindow
222 <tt/void InitDrawWindow (struct window *myWindow)/
224 This function only copies the contents of <tt/myWindow/ into the system area of <tt/drawWindow/. Use it
225 if for some reason you have to keep your window data out of the zero page space.
229 <tt/void Rectangle (void)/
231 This draws on screen a rectangle filled with the current pattern.
233 <sect3>FrameRectangle
235 <tt/void FrameRectangle (char pattern)/
237 This one draws a frame with the given bit pattern (not a pattern from the GEOS palette).
239 <sect3>InvertRectangle
241 <tt/void InvertRectangle (void)/
243 Just as the name says...
245 <sect3>ImprintRectangle and RecoverRectangle
247 <tt/void ImprintRectangle (void)/
249 <tt/void RecoverRectangle (void)/
251 These two functions are for copying parts of the screen to (<tt/Imprint/) and from (<tt/Recover/) the
252 backbuffer of the screen. For example when drawing a new menu box GEOS first uses
253 <tt/ImprintRectangle/ to save the area under the box, and restores it by <tt/RecoverRectangle/ upon
256 <sect2>Line Functions
258 The GEOS drawing package is optimized so there are different functions for drawing vertical and
261 <sect3>HorizontalLine
263 <tt/void HorizontalLine (char pattern, char y, unsigned xStart, unsigned xEnd)/
265 This function draws a horizontal line using the given pattern. Note that <tt/pattern/ is not a pattern
266 number as set in <tt/SetPattern/ but a true bit pattern.
270 <tt/void InvertLine (char y, unsigned xStart, unsigned xEnd)/
272 There is only a horizontal version.
276 <tt/void RecoverLine (char y, unsigned xStart, unsigned xEnd)/
278 This function recovers a single line. It is utilized by <tt/RecoverRectangle/. See its description
283 <tt/void VerticalLine (char pattern, char yStart, char yEnd, unsigned x)/
285 This function draws a vertical line using the given pattern. Note that <tt/pattern/ is not a pattern
286 number as set in <tt/SetPattern/ but a true bit pattern.
290 <tt/void DrawLine (char mode, struct window *myWindow)/
292 The <tt/top/ parameters of <tt/struct window/ describe the starting point of the line, while
293 <tt/bottom/ ones are for the ending point. If <tt/mode/ is <tt/DRAW_DRAW/ then the current pattern from
294 <tt/SetPattern/ is used for drawing. If <tt/mode/ is <tt/DRAW_ERASE/ then the line is erased from the
295 screen. If <tt/mode/ is <tt/DRAW_COPY/ then the line is copied from/to back/frontbuffer, according to
296 the <tt/dispBufferOn/ setting.
298 <sect2>Point Functions
300 The parameters to these two functions are passed by a pointer to an own <tt/struct pixel/ filled with
305 <tt/void DrawPoint (char mode, struct pixel *myPixel)/
307 Depending on <tt/mode/ (see <tt/DrawLine/) draws/erases/copies a single point
312 <tt/char TestPoint (struct pixel *myPixel)/
314 This function tests if the given pixel is set and returns <tt/true/ (non-zero) or <tt/false/ (zero).
316 <sect2>Character and string output
320 <tt/void PutChar (char character, char y, unsigned x)/
322 This function outputs a single character using the current style and font to the screen.
326 <tt/void PutString (char *myString, char y, unsigned x)/
328 Same as <tt/PutChar/ except the fact that you can output a whole <tt/NULL/-terminated string.
329 See <tt/ggraph.h/ for the list of tokens that you can also place in the string - like <tt/CBOLDON/ or
334 <tt/void PutDecimal (char parameter, unsigned value, char y, unsigned x)/
336 This function converts <tt/value/ to its decimal representation and outputs it to the screen.
337 The <tt/parameter/ is the field width in pixels (range 1-31) and the mode bits. Depending on them
338 the string can be filled with zeroes (the string is always 5 characters long) or not and left or right
339 justified to the given pixel. See <tt/ggraph.h/ for predefined values for <tt/parameter/.
345 <tt/char GetCharWidth (char character)/
347 This function returns the real width (in pixels) of the given character with the current font. It can be used
348 for counting the length of a string on the screen, allowing for indentation or justification.
352 <tt/void LoadCharSet (struct fontdesc *myFont)/
354 This function forces GEOS to use the given font. <tt/myFont/ should be casted from a
355 pointer to the start of the area where a record from a font file (VLIR structure) was loaded.
359 <tt/void UseSystemFont (void)/
361 This function forces GEOS to use the built-in BSW font.
363 <sect2>Bitmap handling
365 I'm not quite sure how these functions are working (except <tt/BitmapUp/) so you should
366 probably look into the library sources and compare it with your knowledge. Please let me know
367 if something is wrong or broken.
371 <tt/void BitmapUp (struct iconpic *myPic)/
373 This function unpacks the bitmap and places it on the screen - just as you set it in the
374 <tt/struct iconpic/ pointer which you pass. See <tt/gstruct.h/ for a description of this
375 structure. Note that you can only use packed GEOS bitmaps - a simple Photo Scrap is in this format.
379 <tt/void BitmapClip (char skipLeft, char skipRight, unsigned skipTop, struct iconpic *myPic)/
381 This function acts similar to <tt/BitmapUp/ but you can also define which parts of the bitmap are
382 to be drawn - you give the number of columns (8-pixel) to skip on the right and left of the bitmap,
383 and the number of rows to skip from the top if it.
387 <tt/void BitOtherClip (void *proc1, void *proc2, char skipLeft, char skip Right, unsigned skipTop,
388 struct iconpic *myPic)/
390 Similar to the previous one with some extension. <tt/proc1/ is called before reading a byte (it
391 returns in .A the next value), and <tt/proc2/ is called every time the parser reads a byte which is
392 not a piece of a pattern (byte of code greater than 219). Both procedures should be written
393 separately in assembler and declared as <tt/__fastcall__/ returning char.
395 <sect1>Menus and Icons
397 Here you will find information about functions related with menus and icons.
401 Menus are essential for a GUI. GEOS can handle only one menu at a time, but each menu can call
402 another one, which results in a submenu tree. There can be up to 8 menu levels, each one with up
405 Menus are initialized with <tt/DoMenu/ and then the Kernal takes care of everything. Your code
406 (called from an event handler) should be a function without parameters, returning void. You should
407 use <tt/DoPreviousMenu/ or <tt/GotoFirstMenu/ at least once in its code to have the screen clean.
411 <tt/void DoMenu (struct menu *myMenu)/
413 This function initializes the GEOS menu processor and exits. See <tt/DoMenu structure/ for more
414 information about it. Know that many GEOS applications just initialize the screen, menu and
415 exit to the main Kernal loop, this proves the power of <tt/DoMenu/.
419 <tt/void ReDoMenu (void)/
421 This simply redraws the menu at the lowest level. It works like calling <tt/DoMenu/ again with
426 <tt/void RecoverMenu (void)/
428 This function erases the current menu from the screen. It doesn't change the menu level.
430 <sect3>RecoverAllMenus
432 <tt/void RecoverAllMenus (void)/
434 This calls <tt/RecoverMenu/ and erases all menus from the screen. Then the menu level is
437 <sect3>DoPreviousMenu
439 <tt/void DoPreviousMenu (void)/
441 This functions causes the menu processor to go back one menu level. You should use it in menu
442 handler code to have the screen clean.
446 <tt/void GotoFirstMenu (void)/
448 This one jumps back to the topmost menu. If there is only a menu and one submenu it works the
449 same as <tt/DoPreviousMenu/.
451 <sect2>Icon Functions
453 Icons are working similar to menus except the fact that there is only one level. Icons are
454 defined as a screen area filled with a bitmap, but if you would setup icons and erase the
455 screen they would still be active and clicking in the place where formerly an icon was would cause
456 an effect. Similarly if you would setup icons and then turn them off with <tt/ClearMouseMode/
457 the bitmap would still be on the screen but clicking on it would not cause any action.
458 There is only one, but powerful icon function.
462 <tt/void DoIcons (struct icontab *myIconTab)/
464 This function initializes all icons that are present on the screen at once. For more information
465 look at the <tt/Icons/ chapter in this manual.
469 This chapter covers the most powerful GEOS user interface function - <tt/DoDlgBox/.
475 <tt/char DoDlgBox (char *dialogString)/
477 This function returns one byte. It can be the value of one of six standard icons (see <tt/gdlgbox.h/)
478 or whatever the closing routine passes. Register <tt/r0L/ also contains this value.
480 Read the structures chapter for the specs of the <tt/dialogString/.
482 <sect3>RstrFrmDialogue
484 <tt/char RstrFrmDialogue/
486 This function is called from within DoDlgBox event. It immediately closes the DialogBox and returns
487 the owner ID (or whatever caller has in the .A register).
489 <sect2>GEOSLib extensions
491 To simplify the usage of DoDlgBox from C I wrote some helper functions - wrappers for DoDlgBox,
492 with predefined data. In one word - these are standard DialogBoxes you can see in almost every
495 <sect3>DlgBoxYesNo, DlgBoxOkCancel, DlgBoxOk
497 <tt/char DlgBoxYesNo (char *line1, char *line2)/
499 <tt/char DlgBoxOkCancel (char *line1, char *line2)/
501 <tt/void DlgBoxOk (char *line1, char *line2)/
503 These function show two lines of text in a standard-sized DialogBox. You can read the code of the
504 pressed icon from the return value. E.g. for <tt/DlgBoxYesNo/ it can only be <tt/YES/ or <tt/NO/.
505 You can pass an empty string or NULL to get a blank line.
507 <sect3>DlgBoxGetString
509 <tt/char DlgBoxGetString (char *string, char strlen, char *line1, char *line2)/
511 This function prompts the user to enter a string of at most <tt/strlen/ characters. It is returned
512 in <tt/string/. The two given lines of text are shown above the input line. Please remember
513 that there is also a <tt/CANCEL/ icon in the DialogBox and you should test if user confirmed his
514 input or gave up. The <tt/string/ is also shown so you can place a default input there or remember
515 to place <tt/NULL/ at start.
517 <sect3>DlgBoxFileSelect
519 <tt/char DlgBoxFileSelect (char *class, char filetype, char *filename)/
521 This routine is the standard file selector. It can return <tt/OPEN/, <tt/CANCEL/ or disk error
522 on reading the directory or opening the disk.
523 There is also a <tt/DISK/ icon shown, but it is handled internally. You pass as input parameters
524 <tt/filetype/ and a pointer to a string containing the first part of a file's class. If this string is
525 empty (<tt/NULL/ at the start), then all files with given filetype will be shown.
527 At present this file selector handles only first 16 files of given type and supports only one
532 <tt/char MessageBox (char mode, const char *format, ...)/
534 This function is a more general one. It works very much like <tt/printf/ in a
535 box. The only difference is the <tt/mode/ parameter which allows for placing
536 default icons (see <tt/gdlgbox.h/ for list of possible <tt/MB_/ values).
537 Any too wide text will be clipped to the size of the default window. If <tt/mode/
538 is invalid or equal to <tt/MB_EMPTY/ then the window will be closed
539 after a click. Otherwise the user must choose an icon.
541 Note: Use it if you really need (or if you use it in many places) as
542 it adds quite amount of code to your program.
544 Note: the formatted text <em/cannot exceed/ 255 bytes in length, there is no check
547 <sect1>Mouse, Sprites and Cursors
549 You will find here functions related to sprite and mouse drawing and handling.
551 <sect2>Mouse related functions
553 These cover the mouse - as a general pointing device, but expect users to utilize as different devices
554 as a digital or analog joystick, a mouse, a lightpen or a koalapad (whatever it is).
556 <sect3>StartMouseMode
558 <tt/void StartMouseMode (void)/
560 This function initializes the mouse vectors - <tt/mouseVector/ and <tt/mouseFaultVec/, and then
563 <sect3>ClearMouseMode
565 <tt/void ClearMouseMode (void)/
567 This function disables all mouse activities - icons and menus stop to respond to mouse events,
568 but they are not cleared from the screen.
570 <sect3>MouseUp and MouseOff
572 <tt/void MouseUp (void)/
574 <tt/void MouseOff (void)/
576 The first function turns the mouse pointer on. It appears on the next IRQ. The second one does
577 the opposite - it turns off the pointer, but its position is still updated by the input driver.
581 <tt/char IsMseInRegion (struct window *myWindow)/
583 This function tests if the mouse pointer is actually in the given range of the screen. See <tt/gsprite.h/ for
584 a description of the bits in the return values - they describe the position in detail.
588 You are free to use any of the eight sprites, but keep in mind that sprite 0 is actually the mouse
589 pointer and sprite 1 can be overwritten when using a text prompt. You don't have to worry about
590 40/80 column issues because GEOS128 has a pretty good sprite emulator for the VDC.
594 <tt/void DrawSprite (char sprite, char *mySprite)/
596 This function initializes the sprite data. <tt/mySprite/ is a 63-byte table with bitmap data, which
597 is copied to the system sprite area (at <tt/sprpic/ - see <tt/gsym.h/). Hardware sprite registers are
598 not initialized and the sprite is not yet visible.
602 <tt/void PosSprite (char sprite, struct pixel *myPixel)/
604 This function positions the sprite on the screen. The given coordinates are screen ones - they are
605 converted to sprite coordinates by GEOS. Due to this you cannot use this function to position your
606 sprite off the left or top to the screen.
608 <sect3>EnablSprite and DisablSprite
610 <tt/void EnablSprite (char sprite)/
612 <tt/void DisablSprite (char sprite)/
614 These two functions are responsible for making the sprite visible or not.
616 <sect2>Cursors and Console
618 <sect3>InitTextPrompt
620 <tt/void InitTextPrompt (char height)/
622 This function initializes sprite 1 for a text prompt with given <tt/height/. This parameter can be in
625 <sect3>PromptOn and PromptOff
627 <tt/void PromptOn (struct pixel *myPixel)/
629 <tt/void PromptOff (void)/
631 The first function places a text prompt in given place and enables blinking.
632 The second one is pretty self-explanatory.
636 <tt/char GetNextChar (void)/
638 This function gets the next character from the keyboard queue. If the queue is empty it returns
639 <tt/NULL/, otherwise you receive the true ASCII code of a character or the value of a special (function)
640 key. See <tt/gsprite.h/ for the list of them.
644 This chapter covers rather low-level disk routines. You should use them with care, because
645 you may easily corrupt data on disks. Also remember that contemporary GEOS supports many various
646 devices and sticking to 1541 track layout (e.g. expecting the directory on track 18) might be
649 For some purposes you might consider using the <tt/dio.h/ interface to disk access. It is native.
651 All GEOS disk functions return an error code in the X register. In some cases this is returned by the
652 GEOSLib function (if its type is <tt/char/), but in all cases the last error is saved in the <tt/__oserror/
653 location. If it is nonzero - an error occured. See <tt/gdisk.h/ for the list of possible errorcodes.
654 You need to include <tt/errno.h/ to get <tt/__oserror/, together with the standard <tt/errno/. The
655 latter gives less verbose, but still usable information and can be used with <tt/strerror/.
656 Probably you will get more information using <tt/_stroserror/ in a similar way.
658 For passing parameters use almost always a pointer to your data e.g. <tt/ReadBuff (&myTrSe)/.
660 <sect2>Buffer functions
662 These functions take a single data sector (256 bytes) to read or write on the disk.
664 <sect3>ReadBuff and Writebuff
666 <tt/char ReadBuff (struct tr_se *myTrSe)/
668 <tt/char WriteBuff (struct tr_se *myTrSe)/
670 These functions read and write a sector placed at <tt/diskBlkBuf/.
672 <sect3>GetBlock and ReadBlock
674 <tt/char GetBlock (struct tr_se *myTrSe, char *buffer)/
676 <tt/char ReadBlock (struct tr_se *myTrSe, char *buffer)/
678 These two functions read a single block directly to the 256 byte array placed at <tt/buffer/.
679 The difference between them is that <tt/GetBlock/ initializes TurboDos in the drive if it was not
680 enabled. <tt/ReadBlock/ assumes that it is already enabled thus being slightly faster.
682 <sect3>PutBlock, WriteBlock, VerWriteBlock
684 <tt/char PutBlock (struct tr_se *myTrSe, char *buffer)/
686 <tt/char WriteBlock (struct tr_se *myTrSe, char *buffer)/
688 <tt/char VerWriteBlock (struct tr_se *myTrSe, char *buffer)/
690 Similar to previous but needed for writing the disk. <tt/VerWriteBlock/ verifies the data after
691 writing. In case of an error five tries are attempted before an error code is returned.
693 <sect2>Directory header
695 The functions described here operate on <tt/curDirHeader/ where the current disk header is stored.
696 On larger (than 1541) capacity drives the second part of the directory header is in <tt/dir2Head/.
700 <tt/void GetPtrCurDkNm (char *diskName)/
702 This function fills the given character string with the name of current disk. It is converted to C
703 standard - the string is terminated with <tt/NULL/ character instead of code 160 as in Commodore DOS.
704 Note that the passed pointer must point to an array of at least 17 bytes.
706 <sect3>GetDirHead and PutDirHead
708 <tt/char GetDirHead (void)/
710 <tt/char PutDirHead (void)/
712 These functions read and write the directory header. You should use <tt/GetDirHead/ before
713 using any functions described below, and you should use <tt/PutDirHead/ to save the changes on the
714 disk. Otherwise they will be lost. Operating area is the <tt/curDirHead/.
718 <tt/unsigned CalcBlksFree (void)/
720 This function returns the number of free blocks on the current disk. It is counted using data in
721 <tt/curDirHead/ so you must initialize the disk before calling it.
725 <tt/char ChkDskGEOS (void)/
727 This functions checks <tt/curDirHead/ for the GEOS Format identifier. It returns either true or false,
728 and also sets <tt/isGEOS/ properly. You must initialize the disk before using this.
732 <tt/char SetGEOSDisk (void)/
734 This function initializes disk for use with GEOS. It sets the indicator in directory header and
735 allocates a sector for the directory of border files. You don't need to initialize the disk before
740 <tt/char FindBAMBit (struct tr_se *myTrSe)/
742 This function returns the bit value from the BAM (Block Allocation Map) for the given sector. The bit is
743 set if the sector is free to use. The returned value is always zero if the sector is already allocated.
744 In fact, this function could be used in a following way:
746 #define BlockInUse FindBAMBit
748 if (!BlockInUse(&myTrSe)) {
749 ... block not allocated ...
753 Anyway, I feel that this function is too low-level.
755 <sect3>BlkAlloc and NxtBlkAlloc
757 <tt/char BlkAlloc (struct tr_se output[&rsqb, unsigned length)/
759 <tt/char NxtBlkAlloc (struct tr_se *myTrSe, struct tr_se output[&rsqb, unsigned length)/
761 Both functions allocate enough disk sectors to fit <tt/length/ bytes in them. You
762 find the output in <tt/output/ which is a table of <tt/struct tr_se/. The last entry will have the
763 track equal to 0 and sector equal to 255. The simplest way of using them is to use
764 predefined space in the GEOS data space and pass <tt/fileTrScTab/, which is a predefined table.
766 The difference between those two is that <tt/NextBlkAlloc/ starts allocating from the given sector,
767 and <tt/BlkAlloc/ starts from the first nonused sector.
769 You need to use <tt/PutDirHead/ later to save any changes in BAM.
773 <tt/char FreeBlock (struct tr_se *myTrSe)/
775 Simply deallocates a block in the BAM. You need to update the BAM with <tt/PutDirHead/.
779 <tt/struct tr_se SetNextFree (struct tr_se *myTrSe)/
781 This function finds the first free sector starting from given track and sector and allocates it.
782 It might return the same argument if the given block is not allocated. I wanted it to be type
783 clean, but this made the usage a bit tricky. To assign a value to your own <tt/struct tr_se/ you have to
784 cast both variables to <tt/unsigned/. E.g.
788 (unsigned)myTrSe=(unsigned)SetNextFree(&otherTrSe);
791 In this example <tt/otherTrSe/ can be replaced by <tt/myTrSe/.
793 Note: you <em/must/ use casting to have the correct values.
795 <sect2>Low-level disk IO
797 Functions described here are more usable in Kernal or drivers code, less common in applications,
798 but who knows, maybe someone will need them.
800 <sect3>EnterTurbo, ExitTurbo, PurgeTurbo
802 <tt/void EnterTurbo (void)/
804 <tt/void ExitTurbo (void)/
806 <tt/void PurgeTurbo (void)/
808 These functions are the interface to the GEOS TurboDos feature which makes slow Commodore drives a bit
809 more usable. <tt/EnterTurbo/ enables TurboDos unless it is already enabled. If not, then you will
810 have to wait a bit to transfer the TurboDos code into disk drive RAM. <tt/ExitTurbo/ disables TurboDos.
811 This is useful for sending some DOS commands to a drive e.g. for formatting. Note that before any
812 interaction with the Kernal in ROM you have to call <tt/InitForIO/. You don't have to worry about speed.
813 <tt/EnterTurbo/ will only enable TurboDos (no code transfer) if TurboDos was disabled with
814 <tt/ExitTurbo/. <tt/PurgeTurbo/ acts differently from <tt/ExitTurbo/ - it not only disables TurboDos,
815 but also removes it from drive RAM (not quite true, but it works like that). After using
816 <tt/PurgeTurbo/ the next call to <tt/EnterTurbo/ will reload drive RAM.
818 <sect3>ChangeDiskDevice
820 <tt/char ChangeDiskDevice (char newDevice)/
822 This function changes the device number of the current device (in fact drives only) to the given one. It is
823 usable for swapping drives. There's no check if the given <tt/newDevice/ already exist, so if you want
824 to change the logical number of drive 8 to 9 and you already have a drive number 9 then GEOS will probably
825 hang on disk access. Use safe, large numbers. Note that the safe IEC range is 8-30.
827 <sect2>Disk Initialization
829 GEOS has two functions for initialization ('logging in' as they say on CP/M) of a disk.
832 <tt/char OpenDisk (void)/
834 This function initializes everything for a new disk. It loads and enables TurboDos if needed.
835 Then the disk is initialized with <tt/NewDisk/. Next, <tt/GetDirHead/ initializes <tt/curDirHead/.
836 Disk names are compared and if they differ then the disk cache on REU is cleared. Finally the format is
837 checked with <tt/ChkDkGEOS/ and the disk name is updated in the internal tables.
841 <tt/char NewDisk (void)/
843 This function is similar to the DOS command I. It clears the REU cache and enables TurboDos if needed.
847 This section covers the GEOS file interface.
849 <sect2>Directory handling
851 The functions described here are common for SEQ and VLIR structures.
853 <sect3>Get1stDirEntry and GetNxtDirEntry
855 <tt/struct filehandle *Get1stDirEntry (void)/
857 <tt/struct filehandle *GetNxtDirEntry (void)/
859 These two functions are best suited for scanning the whole directory for particular files. Note that
860 the returned filehandles describe all file slots in the directory - even those with deleted files.
861 The return value can be obtained by casting both sides to <tt/unsigned/ - as in the <tt/SetNextFree/
862 function or read directly after a call to those two functions from <tt/r5/. The current sector number
863 is in <tt/r1/ and the sector data itself is in <tt/diskBlkBuf/.
867 <tt/char FindFile (char *fName)/
869 This function scans the whole directory for the given filename. It returns either 0 (success) or 5
870 (FILE_NOT_FOUND, defined in <tt/gdisk.h/) or any other fatal disk read error. After a successful
871 <tt/FindFile/ you will have <tt/struct filehandle/ at <tt/dirEntryBuf/ filled with the file's data and
872 other registers set as described in <tt/GetNxtDirEntry/.
876 <tt/char FindFTypes (char *buffer, char fType, char fMaxNum, char *classTxt)/
878 This function scans the directory and fills a table at <tt/buffer/ with <tt/char [17]/ entries.
879 <tt/fType/ is the GEOS type of the searched files and <tt/classTxt/ is a string for the Class field in the file
880 header. Class matches if the given string is equal or shorter than that found in the file's header block.
881 If you want just to find all files with the given GEOS type you should pass an empty string or <tt/NULL/ as
882 <tt/classTxt/. Be warned that for searching <tt/NON_GEOS/ files you must pass <tt/NULL/ as <tt/classTxt/.
883 <tt/fMaxNum/ is the maximal number of files to find, thus the <tt/buffer/ must provide an area of size
884 equal to <tt/17 * fMaxNum/. This function returns the number of found files, ranging from 0 to number
885 passed as <tt/fMaxNum/. The return value can be also restored from <tt/r7H/.
889 <tt/char DeleteFile (char *fName)/
891 This function deletes a file by its name. It works for SEQ and VLIR files.
895 <tt/char RenameFile (char *oldName, char *newName)/
897 I think it is obvious...
901 <tt/char GetFHdrInfo (struct filehandle *myFile)/
903 This function loads the file header into the <tt/fileHeader/ buffer. Using after e.g. <tt/FindFile/
904 you can pass the address of <tt/dirEntryBuf/.
906 <sect2>Common and SEQ structure
908 Functions described here are common for SEQ and VLIR structures because the arguments passed are the
909 starting track and sector which may point either to the start of a chain for VLIR or the data for SEQ.
913 <tt/char __fastcall__ GetFile(char flag, const char *fname, const char *loadaddr, const char *datadname, const char *datafname)/
915 This routine loads and runs a given file <tt/fname/. The file must be one of following types:
916 <tt/SYSTEM, DESK_ACC, APPLICATION, APPL_DATA, PRINTER,/ or <tt/INPUT_DEVICE/. The execution
917 address is taken from the file header. If it is zero, then the file is only loaded. Only the first chain
918 from VLIR files is loaded. If <tt/flag/ has bit 0 set then the load address is taken from <tt/loadaddr/
919 and not from the file header. In this case <tt/APPLICATION/ files will be only loaded, not executed.
920 This does not apply to <tt/DESK_ACC/. If either bit 6 or 7 of <tt/flag/ are set, then 16 bytes from
921 <tt/datadname/ are copied to <tt/dataDiskName/ and 16 bytes from <tt/datafname/ go to <tt/dataFileName/
922 thus becoming parameters for the new application. Pass <tt/NULL/ for any unused parameter.
926 <tt/char ReadFile (struct tr_se *myTrSe, char *buffer, unsigned fLength)/
928 This function reads at most <tt/fLength/ bytes into <tt/buffer/ from chained sectors starting at
933 <tt/char ReadByte (void)/
935 This function returns the next byte from a file. Before the first call to it you must load <tt/r5/
936 with <tt/NULL/, <tt/r4/ with the sector buffer address and <tt/r1/ with the track and sector of the
937 first block of a file.
938 Remember to not modify <tt/r1/, <tt/r4/ and <tt/r5/. These registers must be preserved between
939 calls to <tt/ReadByte/.
941 The returned value is valid only if there was no error. The end of file is marked as <tt/BFR_OVERFLOW/
942 in <tt/__oserror/, this is set when trying to read one byte after the end of file, in this case the
943 returned value is invalid.
947 <tt/char SaveFile (char skip, struct fileheader *myHeader)/
949 <tt/SaveFile/ will take care of everything needed to create a GEOS file, no matter if VLIR of SEQ
950 structure. All you need to do is to place the data in the proper place and prepare a header which will
951 contain all information about a file. The <tt/skip/ parameter says how many directory pages you
952 want to skip before searching for a free slot for the directory entry. In most cases you will put
955 You have to declare a <tt/struct fileheader/ and fill it with proper values. There is only one
956 difference - the first two bytes which are a link to a nonexistent next sector are replaced by a
957 pointer to the DOS filename of the file.
959 When saving sequential files the two most important fields in <tt/struct fileheader/ are <tt/fileheader.load_address/
960 and <tt/fileheader.end_address/.
964 <tt/char FreeFile (struct tr_se myTable[])/
966 This function deallocates all sectors contained in the passed table.
970 <tt/char FollowChain(struct tr_se *myTrSe, char *buffer)/
972 This function fills a <tt/struct tr_se/ table at <tt/buffer/ with the sector numbers for a chain of
973 sectors starting with <tt/myTrSe/. You can pass such data (<tt/buffer/) to e.g. <tt/FreeFile/.
975 <sect2>VLIR structure
977 Here is information about VLIR files (later called RecordFiles) and functions.
979 A VLIR structure file consists of up to 127 SEQ-like files called records. Each record is like one
980 SEQ structure file. Records are grouped together, described by a common name - the VLIR file name and
981 an own number. Each record pointed to by its number is described by the starting track and sector numbers.
982 VLIR structures allow records to be empty (<tt/tr_se/ of such record is equal to <tt/{NULL,$ff}/),
983 or even non-exist (<tt/{NULL,NULL}/). Any other numbers represent the starting track and sector of
986 In GEOS there can be only one file opened at a time. Upon opening a VLIR file some information
987 about it is copied into memory. You can retrieve the records table at <tt/fileTrScTab/ (table of
988 128 <tt/struct tr_se/) and from <tt/VLIRInfo/ (<tt/struct VLIR_info/.
989 E.g. the size of whole VLIR file can be retrieved by reading <tt/VLIRInfo.fileSize/.
991 <sect3>OpenRecordFile
993 <tt/char OpenRecordFile (char *fName)/
995 This function finds and opens a given file. An error is returned if the file is not found or if it is not
996 in VLIR format. Information in <tt/VLIRInfo/ is initialized. VLIR track and sector table is
997 loaded at <tt/fileTrScTab/ and will be valid until a call to <tt/CloseRecordFile/ so don't modify it.
998 You should call <tt/PointRecord/ before trying to do something with the file.
1000 <sect3>CloseRecordFile
1002 <tt/char CloseRecordFile (void)/
1004 This function calls <tt/UpdateRecordFile/ and clears internal GEOS variables.
1006 <sect3>UpdateRecordFile
1008 <tt/char UpdateRecordFile (void)/
1010 This function will check the <tt/VLIRInfo.fileWritten/ flag and if it is set, then <tt/curDirHead/ is
1011 updated along with size and date stamps in the directory entry.
1015 <tt/char PointRecord (char recordNumber)/
1017 This function will setup internal variables (and <tt/VLIRInfo.curRecord/) and return the track and
1018 sector of the given record in <tt/r1/. Note that the data may not be valid (if the record is non-existing
1019 you will get 0,0 and if it is empty - 255,0).
1021 <sect3>NextRecord and PreviousRecord
1023 <tt/char NextRecord (void)/
1025 <tt/char PreviousRecord (void)/
1027 These two work like <tt/PointRecord/. Names are self-explanatory.
1031 <tt/char AppendRecord (void)/
1033 This function will append an empty record (pair of 255,0) to the current VLIR track and sector
1034 table. It will also set <tt/VLIRInfo.curRecord/ to its number.
1038 <tt/char DeleteRecord (void)/
1040 This function will remove the current record from the table, and move all current+1 records one place
1041 back (in the table). Note that there's no BAM update and you must call <tt/UpdateRecordFile/ to
1046 <tt/char InsertRecord (void)/
1048 This function will insert an empty record in place of <tt/VLIRInfo.curRecord/ and move all following
1049 records in the table one place forward (contents of <tt/VLIRInfo.curRecord/ after a call to <tt/InsertRecord/
1050 can be found in <tt/VLIRInfo.curRecord + 1/).
1052 <sect3>ReadRecord and WriteRecord
1054 <tt/char ReadRecord (char *buffer, unsigned fLength)/
1056 <tt/char WriteRecord (char *buffer, unsigned fLength)/
1058 This function will load or save at most <tt/fLength/ bytes from the currently pointed record into or from
1061 <sect1>Memory and Strings
1063 The functions covered in this section are common for the whole C world - copying memory parts and
1064 strings is one of the main computer tasks. GEOS also has an interface to do this. These functions
1065 are replacements for those like <tt/memset, memcpy, strcpy/ etc. from standard libraries.
1066 If you are dealing with short strings (up to 255 characters) you should use these functions
1067 instead of standard ones, e.g. <tt/CopyString/ instead of <tt/strcpy/. It will work faster.
1069 However some of them have slightly different calling conventions (order of arguments to be specific),
1070 so please check their syntax here before a direct replacement.
1072 Please note that the memory areas described here as <em/strings/ are up to 255 characters (without
1073 counting the terminating <tt/NULL/), and <em/regions/ can cover the whole 64K of memory.
1077 <tt/void CopyString (char *dest, char *src)/
1079 This function copies the string from <tt/src/ to <tt/dest/, until it reaches <tt/NULL/. The <tt/NULL/
1084 <tt/char CmpString (char *s1, char *s2)/
1086 This function compares the strings <tt/s1/ to <tt/s2/ for equality - this is case sensitive, and both
1087 strings have to have the same length. It returns either <tt/true/ (non-zero) or <tt/false/ (zero).
1089 <sect2>CopyFString and CmpFString
1091 <tt/void CopyFString (char length, char *dest, char *src)/
1093 <tt/char CmpFString (char length, char *s1, char *s2)/
1095 These two are similar to <tt/CopyString/ and <tt/CmpString/ except the fact, that you provide
1096 the length of the copied or compared strings. The strings can also contain several <tt/NULL/
1097 characters - they are not treated as delimiters.
1101 <tt/unsigned CRC (char *src, unsigned length)/
1103 This function calculates the CRC checksum for the given memory range. I don't know if it is
1104 compatible with standard CRC routines.
1106 <sect2>FillRam and ClearRam
1108 <tt/void *FillRam (char *dest, char value, unsigned length)/
1110 <tt/void *ClearRam (char *dest, unsigned length)/
1112 Both functions are filling the given memory range. <tt/ClearRam/ fills with <tt/0s/, while
1113 <tt/FillRam/ uses the given <tt/value/. Be warned that these functions destroy <tt/r0, r1 and
1114 r2L/ registers. The functions are aliases for <tt/memset/ and <tt/bzero/, respectively.
1118 <tt/void *MoveData (char *dest, char *src, unsigned length)/
1120 This functions copies one memory region to another. There are checks for an overlap and the
1121 non-destructive method is chosen. Be warned that this function destroys contents of the
1122 <tt/r0, r1 and r2/ registers. This function is an alias for <tt/memcpy/.
1126 <tt/void InitRam (char *table)/
1128 This function allows to initialize multiple memory locations with single bytes or strings.
1129 This is done with a <tt/table/ where everything is defined. See the structures chapter for a description of
1130 <tt/InitRam's/ command string.
1132 <sect2>StashRAM, FetchRAM, SwapRAM, and VerifyRAM
1134 <tt/void StashRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1136 <tt/void FetchRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1138 <tt/void SwapRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1140 <tt/ char VerifyRAM (char bank, unsigned length, char *reuAddress, char *cpuAddress)/
1142 These functions are the interface to a REU - Ram Expansion Unit. I think that they are self-explanatory.
1143 You can check for REU presence by taking the value of <tt/ramExpSize/. You have to do it before
1144 using any of these functions.
1146 <sect1>Processes and Multitasking
1148 Weird? Not at all. GEOS has some limited multitasking ability. You can set up a chain of functions
1149 called in specified intervals and you can put the main program to sleep without disturbing other
1150 tasks and making the user interface unresponsive.
1152 <sect2>InitProcesses
1154 <tt/void InitProcesses (char number, struct process *processTab)/
1156 This is the main initialization routine. After calling it processes are set up, but not
1157 enabled. The parameters for <tt/InitProcesses/ are:
1159 <item><tt/number/ - number of processes
1160 <item><tt/processTab/ - a table of <tt/struct process/, with size equal to <tt/number/
1163 A single task is described by an entry in <tt/processTab/, it contains two values - a <tt/pointer/ to
1164 the task function and a number of <tt/jiffies/ which describe the delay between calls to task. On PAL
1165 systems there are 50 jiffies per second, while on NTSC there are 60.
1167 The maximum number of tasks is 20. Be warned that GEOS doesn't check if parameters are valid and
1168 if <tt/processTab/ would be too large it would overwrite existing data in GEOS space.
1170 There's one important thing - the last entry in <tt/processTab/ has to be <tt/NULL,NULL/, so the
1171 maximum size of <tt/processTab/ is equal to 21.
1173 See the description of <tt/process/ structure for a more detailed discussion on this.
1175 <sect2>RestartProcess and EnableProcess
1177 <tt/void RestartProcess (char processNumber)/
1179 <tt/void EnableProcess (char processNumber)/
1181 These two functions start the task counter. <tt/RestartProcess/ should be called for each process
1182 after <tt/InitProcesses/, because it resets all flags and counters and it starts the counters.
1184 <tt/RestartProcess/ enables the counters and sets their initial value to that given in <tt/processTab/.
1186 <tt/EnableProcess/ forces the given process to execute by simulating the timer expiring.
1188 <sect2>BlockProcess and UnblockProcess
1190 <tt/void BlockProcess (char processNumber)/
1192 <tt/void UnblockProcess (char processNumber)/
1194 <tt/BlockProcess/ disables the execution of the given process, but this does not disable the timers.
1195 It means that if you call <tt/UnblockProcess/ before the timer runs out, the process will be executed.
1197 <tt/UnblockProcess/ does the opposite.
1199 <sect2>FreezeProcess and UnfreezeProcess
1201 <tt/void FreezeProcess (char processNumber)/
1203 <tt/void UnfreezeProcess (char processNumber)/
1205 <tt/FreezeProcess/ disables timer for given process. <tt/UnfreezeProcess/ does the opposite.
1206 This is not equal to <tt/RestartProcess/ as timers are not reloaded with initial value.
1210 <tt/void Sleep (unsigned jiffies)/
1212 This function is a multitasking sleep - the program is halted, but it doesn't block other functions
1213 e.g. callbacks from menus and icons.
1214 The only argument here is the number of jiffies to wait until the app will wake up. It depends on the
1215 video mode (PAL or NTSC) how many jiffies there are per second (50 or 60, respectively).
1216 If you don't want to worry about it and need only full second resolution, call the standard
1217 <tt/sleep/ function from <tt/unistd.h/.
1219 <sect1>System Functions
1223 <tt/void FirstInit (void)/
1225 This function initializes some GEOS variables and mouse parameters. This is called on GEOS boot
1226 up. You shouldn't use this unless you know what you are doing.
1228 <sect2>InitForIO and DoneWithIO
1230 <tt/void InitForIO (void)/
1232 <tt/void DoneWithIO (void)/
1234 These functions are called by some disk routines. You should call them only if you want to
1235 do something with IO registers or call one of the Kernal ROM routines. Note that this is rather an
1236 expensive way of turning off IRQs and enabling IO.
1240 <tt/void MainLoop (void)/
1242 Returns control to the system. Any code between call to <tt/MainLoop/ and the end of current
1243 function will never be executed. When in <tt/MainLoop/ the system waits for your action - using
1244 icons, keyboard or menus to force some specific action from the program. You have to define
1245 proper handlers before that.
1249 <tt/void EnterDeskTop (void)/
1251 This is an alias for <tt/exit(0)/ so you will never burn yourself. Anyway, you should not
1252 use it. Always use <tt/exit()/ instead. Library destructors and functions registered with
1253 <tt/atexit()/ are called.
1257 <tt/void ToBASIC (void)/
1259 This one is another way of terminating an application - forcing GEOS to shutdown and exit to BASIC.
1260 I was considering whether to include it or not, but maybe someone will need it - which I doubt.
1262 <em/WARNING:/ library destructors and functions registered with <tt/atexit()/ will not be called
1263 so it is quite unsafe way to terminate your program.
1267 <tt/void Panic (void)/
1269 This calls system's <tt/Panic/ handler - it shows a dialog box with the message
1271 System error at:xxxx
1273 where <tt/xxxx/ is last known execution address (caller). By default this is bound to the <tt/BRK/
1274 instruction, but it might be usable in debugging as kind of <tt/assert/. (Note that <tt/assert/
1275 is available as a separate function and will give you more information than that).
1277 The system is halted after a call to <tt/Panic/ which means that library destructors will not be
1278 called and some data may be lost (no wonder you're panicking).
1282 <tt/void CallRoutine (void *myFunct)/
1284 This is a system caller routine. You need to provide a pointer to a function and it will be immediately
1285 called, unless the pointer is equal to <tt/NULL/. This is the main functionality of this function -
1286 you don't need to check if the pointer is valid.
1288 <sect2>GetSerialNumber
1290 <tt/unsigned GetSerialNumber (void)/
1292 This function returns the serial number of the system. It might be used for copy-protection.
1293 However, please remember that Free Software is a true power and you are using it right now.
1297 <tt/char GetRandom (void)/
1299 This function returns a random number. It can be also read from <tt/random/ e.g.
1303 but by calling this function you are sure that the results will be always different.
1304 <tt/random/ is updated once a frame (50Hz PAL) and on every call to <tt/GetRandom/.
1306 Note that this is not the same as the <tt/rand/ function from the standard library. <tt/GetRandom/
1307 will give you unpredictable results (if IRQs occur between calls to it) while
1308 <tt/rand/ conforms to the standard and for a given seed (<tt/srand/) always returns with the
1309 same sequence of values.
1313 <tt/void SetDevice (char device)/
1315 This function sets the current device to the given. It might be used together with <tt/InitForIO/,
1316 <tt/DoneWithIO/ and some Kernal routines. Unless the new device is a disk drive this only sets
1317 new value in <tt/curDevice/, in the other case new disk driver is loaded from REU or internal RAM.
1321 <tt/char get_ostype (void)/
1323 This function returns the GEOS Kernal version combined (by logical OR) with the machine type. Read
1324 <tt/gsys.h/ for definitions of the returned values.
1328 <tt/char get_tv (void)/
1330 This function returns the PAL/NTSC flag combined (by logical OR) with the 40/80 columns flag. This is
1331 not the best way to check if the screen has 40 or 80 columns since a PAL/NTSC check is always
1332 performed and it can take as long as a full raster frame. If you just want to know if the
1333 screen has 40 or 80 columns use the expression <tt/graphMode & 0x80/ which returns <tt/0/ for
1334 40 columns and <tt/0x80/ for 80 columns. Remember that this value can be changed during
1335 runtime. It is unclear if this will work for GEOS 64 so you probably do not want to test
1336 anything if not running under GEOS128. Use <tt/get_ostype/ to check it. Read <tt/gsys.h/ for
1337 definitions of the returned values.
1339 <sect>Library Structures
1341 To simplify usage and optimize passing parameters to functions I have declared several structures
1342 which describe the most common objects. Some of these structures are bound to static addresses in
1343 the GEOS data space (<tt/$8000-$8fff/), so you can use their fields directly in an optimized way.
1344 Please see <tt/gsym.h/ to find them. All structures are defined in <tt/gstruct.h/ and you may
1345 find also some comments there.
1347 <sect1>Graphics Structures
1351 A simple structure describing a point on the screen.
1355 This structure describes a font in one pointsize. There is the current font - <tt/struct fontdesc/
1356 bound to <tt/curFontDesc/. You can also force GEOS to use your own fonts by calling
1357 <tt/LoadCharSet/. You just need to open a VLIR font file and load one record - one pointsize -
1358 somewhere. At the start of this area you already have all data for <tt/fontdesc/ so you can
1359 pass a pointer to the load address of that pointsize to <tt/LoadCharSet/. (Note that although
1360 it has 'Load' in the name, that function loads only GEOS internal data structures, not data
1365 This widely used structure holds the description of a region of the screen. It describes the top-left and
1366 bottom-right corners of a window.
1370 Maybe the name isn't the best - it has nothing with <tt/DoIcons/ but with bitmap functions -
1371 <tt/BitmapUp/ for example. This structure holds the parameters needed to properly decode and show
1372 a bitmap on the screen. The bitmap has to be encoded - if you have some non-GEOS bitmaps simply
1373 convert them to Photo Scraps - this is the format used by all GEOS bitmap functions - <tt/DoIcons/
1378 These structures describe click boxes (icons) that can be placed on screen or in a dialog box.
1382 This is the definition of a single click box. Please see <tt/gstruct.h/ for a description of its fields.
1386 This is the toplevel description of icons to be placed and enabled on the screen. This structure
1387 has the following fields:
1389 <item><tt/char number/ - total number of icons declared here
1390 <item><tt/struct pixel mousepos/ - after finishing <tt/DoIcons/ the mouse pointer will be placed in
1391 this point allowing you to have a hint for the user what the default action is
1392 <item><tt/struct icondef tab[&rsqb/ - this table of size equal to <tt/icontab.number/ contains
1393 descriptions for all icons
1396 <sect1>File and Disk
1400 This simple structure holds the track and sector number of something. Do not expect the track to be
1401 in range 1-35, as GEOS can support many various and weird devices. For example my C128 256K
1402 expansion is utilized as RAMDisk with a layout of 4 tracks of 128 sectors each. However assuming that
1403 a track number equal to 0 is illegal might be wise.
1407 This is a placeholder for a file datestamp. This structure is also present in <tt/struct filehandle/.
1408 GEOS is not Y2K compliant, so if the current file has in <tt/filehandle.date.year/ a value less than 86
1409 you can safely assume that it is e.g. 2004 and not 1904.
1413 This is the main file descriptor. It is either an entry in the directory (returned from file functions)
1414 or its copy in <tt/dirEntryBuf/. This is optimized so you can safely get to the file's year e.g.
1415 by testing <tt/dirEntryBuf.date.year/ - it will be compiled to simple <tt/LDA, STA/.
1419 This structure holds the fileheader description. You can load a file's header into the <tt/fileHeader/
1420 fixed area using <tt/GetFHdrInfo/. (note that <tt/fileHeader/ is a place in memory while
1421 <tt/fileheader/ is a structure).
1422 You will also need your own fileheader for <tt/SaveFile/.
1424 <sect1>System Structures
1428 This structure is defined only for <tt/system_date/. It is slightly different from <tt/f_date/
1429 so I prepared this one. You can e.g. get or set the current time using <tt/system_date.s_hour/ and
1430 <tt/system_date.s_minute/. Accesses to these will be optimized to simple <tt/LDA/ and <tt/STA/
1435 You should declare a table of that type to prepare data for <tt/InitProcesses/. The maximum number
1436 of processes is 20, and the last entry has to be equal to <tt/{NULL,NULL}/, so this table may hold
1437 only 21 entries. The first member of this structure (<tt/pointer/) holds the pointer to the called
1438 function (void returning void), you will probably have to cast that pointer into <tt/unsigned int/.
1439 The second field <tt/jiffies/ holds the amount of time between calls to that function.
1440 On PAL systems there are 50 jiffies per second, while NTSC have 60 of them.
1442 <sect1>A few things in detail...
1444 GEOSLib uses cc65 non-ANSI extensions to easily initialize data in memory. This is done with a
1445 kind of array of unspecified length and unspecified type. Here is how it works:
1447 void example = {
1448 (char)3, (unsigned)3, (char)0 };
1450 Which will be compiled to following string of bytes:
1457 As you see this way it is possible to define data of any type in any order. You must remember to
1458 cast each member to proper type.
1460 <sect2>DoMenu structure
1462 <tt/DoMenu/ is responsible for everything concerned with menu processing. Many, many GEOS programs
1463 are just initializing the screen and menu and returning to <tt/MainLoop/. In GEOSLib it is the same as
1464 returning from <tt/main/ function without using <tt/exit(0)/.
1466 A menu is described by two types of data - menu descriptors and menu items. A descriptor contains
1467 information about the following menu items, and items contain names of entries and either
1468 pointers to functions to execute or, in case of nested menus, pointers to submenu descriptors.
1469 Note that submenu descriptor can be top-level descriptor, there's no difference in structure,
1470 just in the content.
1472 Here is how a single descriptor looks like:
1474 void myMenu = {
1475 (char)top, (char)bottom, // this is the size of the menubox
1476 (unsigned)left, (unsigned)right, // counting all items in the current descriptor
1477 (char)number_of_items | type_of_menu, // number of following items ORed with
1478 // type of this menu, it can be either
1479 // HORIZONTAL or VERTICAL if you will have also bit 6 set then menu won't be closed
1480 // after moving mouse pointer outside the menubox. You can have at most 31 items.
1482 This is followed by <tt/number_of_items/ of following item description.
1485 "menuitemname", (char)item_type, (unsigned)pointer,
1486 "nextitemname", (char)item_type, (unsigned)pointer,
1488 "lastitemname", (char)item_type, (unsigned)pointer };
1489 // Note that there isn't ending <tt/NULL/ or something like that.
1491 <tt/pointer/ is a pointer to something, what it points for depends from <tt/item_type/. This one
1492 can have following values:
1494 <tt/MENU_ACTION/ - a function pointed by <tt/pointer/ will be called after clicking on the menu item
1496 <tt/SUB_MENU/ - <tt/pointer/ points to next menu descriptor - a submenu
1498 Both of them can be ORed with <tt/DYN_SUB_MENU/ and then the <tt/pointer/ points to a function
1499 which will return in <tt/r0/ the needed pointer (to function to execute or a submenu).
1501 For creating nested menus (you can have at most 8 levels of submenus) you need to declare such
1502 a structure for each submenu and top level menu.
1504 <sect2>DoDlgBox command string
1506 <tt/DoDlgBox/ is together with <tt/DoMenu/ one of the most powerful routines in GEOS. It is
1507 responsible for creating dialog boxes, that is windows which task is to interact with the user.
1508 The format of the command string is following:
1510 (window size and position)
1511 (commands and parameters)
1514 There is a custom type defined for the command string: <tt/dlgBoxStr/.
1516 <sect3>Size and position
1518 The first element can be specified in two ways - by using the default size and position or specifying
1519 your own. The first case results in
1521 const dlgBoxStr example = {
1522 DB_DEFPOS (pattern_of_shadow),
1526 And the own size and position would be:
1528 const dlgBoxStr example = {
1529 DB_SETPOS (pattern, top, bottom, left, right)
1536 The next element of the <tt/DoDlgBox/ command string are the commands themselves. The first six commands are
1537 default icons and the number of the selected icon will be returned from window processor. The icons are
1538 <tt/OK, CANCEL, YES, NO, OPEN/, and <tt/DISK/. You can use predefined macros for using them, e.g.:
1541 DB_ICON(OK, DBI_X_0, DBI_Y_0),
1544 Note that the position is counted from top left corner of window, not entire screen and that the 'x'
1545 position is counted in cards (8-pixel) and not in pixels. This is also true for all following commands.
1546 <tt/DBI_X_0/ and <tt/DBI_Y_0/ are predefined (see <tt/gdlgbox.h/ for more), the default positions
1547 which will cause icons to appear on a default window exactly where you would expect them.
1549 <tt/DB_TXTSTR (x, y, text)/ will cause to show the given text in the window.
1551 <tt/DB_VARSTR (x, y, ptr)/ works as above, but here you are passing a pointer to a zero page location
1552 where the address of the text is stored. This is useful for information windows where only the text content
1553 is variable. Consider following:
1557 r15=(unsigned)text; // in code just before call to DoDlgBox
1559 DB_VARSTR (TXT_LN_X, TXT_LN_1_Y, &r15),
1562 will cause the word ``foo'' to appear in the window, but you may store the pointer to any text in
1563 <tt/r15/ (in this case) before the call to DoDlgBox.
1565 <tt/DB_GETSTR(x, y, ptr, length)/ - will add a input-from-keyboard feature. <tt/ptr/ works as in the
1566 previous example and points to the location where the text is to be stored. Note that the contents of this
1567 location will be shown upon creating the window. <tt/length/ is the maximum number of characters to input.
1569 <tt/DB_SYSOPV(ptr)/ - this sets <tt/otherPressVec/ to the given pointer. It is called on every keypress.
1571 <tt/DB_GRPHSTR(ptr)/ - the data for this command is a pointer for <tt/GraphicsString/ commands.
1573 <tt/DB_GETFILES(x, y)/ - for a standard window you should pass 4 for both x and y. This function
1574 draws a file selection box and searches the current drive for files. Before the call to <tt/DoDlgBox/ you
1575 must load <tt/r7L/ with the GEOS filetype of searched files and <tt/r10/ with the class text. In <tt/r5/
1576 you have to load a pointer to a <tt/char[17]/ where the selected filename will be copied. It works
1577 like <tt/FindFTypes/ but is limited to first 16 files.
1579 <tt/DB_OPVEC(ptr)/ - this sets a new pointer for the button press function, if you pass
1580 <tt/RstrFrmDialogue/ here you will cause the window to close after pressing mouse button.
1582 <tt/DB_USRICON(x, y, ptr)/ - places a single user icon (click box) on the window, <tt/ptr/ points at a
1583 <tt/struct icondef/ but fields <tt/x/ and <tt/y/ are not used here. You can have at most 8 click
1584 boxes in a window, this is an internal limit of the GEOS Kernal.
1586 <tt/DB_USRROUT(ptr)/ - this command causes to immediately call the user routine pointed by <tt/ptr/.
1588 <sect2>GraphicsString command string
1590 <tt/GraphicsString/ is a very powerful routine to initialize the whole screen at once. There are
1591 predefined macros for all commands, names are self-explanatory, see them in <tt/ggraph.h/. The last
1592 command has to be <tt/GSTR_END/. There is a custom type defined for the command string: <tt/graphicStr/.
1594 Here is an example for clearing the screen:
1596 const graphicStr example = {
1599 RECTANGLETO(319,199)
1603 <sect2>InitRam table
1605 This type of data is used to initialize one or more bytes in different locations at once. The format is
1608 void example = {
1609 (unsigned)address_to_store_values_at,
1610 (char)number_of_bytes_that_follow,
1611 (char)data,(char)data (...)
1612 // more such definitions
1613 (unsigned)NULL // address of 0 ends the table
1617 <sect2>Intercepting system vectors
1619 It is possible to intercept events and hook into the GEOS Kernal using vectors. Here is a little example:
1621 void_func oldVector;
1623 void NewVectorHandler(void) {
1624 // do something and at the end call the old vector routine
1628 void hook_into_system(void) {
1629 oldVector = mouseVector;
1630 mouseVector = NewVectorHandler;
1633 void remove_hook(void) {
1634 mouseVector = oldVector;
1638 In your <tt/main/ function you should call <tt/hook_into_system()/ but <em/after/ all calls to the GEOS
1639 Kernal (like <tt/DoMenu/, <tt/DoIcons/, etc.) - right before passing control to the <tt/MainLoop()/.
1640 Be warned that vectors are most likely to be changed by the GEOS Kernal also via other functions (like
1641 <tt/GotoFirstMenu/, <tt/DoDlgBox/ and its derivatives etc.). It depends on what Kernal functions
1642 you use and which vectors you altered. Unfortunately there is no exact list for GEOS 2.0, a complete
1643 list for GEOS 1.x can be found in A. Boyce's Programmers' Reference Guide mentioned before. Most of the
1644 information contained there should be still valid for GEOS 2.0. When calling a function that restores
1645 the vector you should add a <tt/hook_into_system()/ call right after it.
1647 It is critical to restore old vector values before exiting the program. If you have more than one
1648 place where you call <tt/exit()/ then it might be worth to register <tt/remove_hook/ function to
1649 be called upon exiting with <tt/atexit(&remove_hook);/ call. This way you will ensure that
1650 such destructor will be always called.
1652 That little example above intercepts <tt/mouseVector/. The <tt/NewVectorHandler/ function will be
1653 called every time the mouse button changes status. Other important vectors you should know about
1656 <item><tt/appMain/ - this is called from within the <tt/MainLoop/ system loop
1657 <item><tt/keyVector/ - called whenever a keypress occurs
1658 <item><tt/intTopVector/ - called at the start of the IRQ routine
1659 <item><tt/intBotVector/ - called at the end of the IRQ routine