author Patrice Mandin <>
Thu, 19 Jan 2006 21:28:52 +0000
changeset 1257 448a9a64537b
parent 1237 a8068adf156b
child 1420 2405517b5eab
permissions -rw-r--r--
[PATCH] SDL_GetVideoMode() does not find best mode, part 2

Following commit 1.51, I come accross a problem when SDL must choose between
several video modes that could suit the one asked.

If I ask 320x240 with this list:
768x480 768x240 640x400 640x200 384x480 384x240 320x400 320x200

The smallest selectables modes are 384x240 and 320x400. And SDL choose the later
in this list, but 384x240 is more suitable. So I added a check to compare
the pixel count (surface) of modes, and select the one which has the smallest
pixel count.

In my example, 384x240 has 92160 pixels, and 320x400 has 128000 pixels. So now
SDL will choose 384x240 for the asked 320x240 mode.
     1 ==============================================================================
     2 Using the Simple DirectMedia Layer on Atari
     3 ==============================================================================
     6     If you want to build SDL from sources to create SDL programs on Atari:
     7         see sections I - II.
     9     If you want to create SDL programs on Atari using SDL binary build,
    10         download it from my web site (URL at end of this file).
    12     If you want to configure a program using SDL on Atari,
    13 	    see sections IV - VI.
    16 ==============================================================================
    17 I.  Building the Simple DirectMedia Layer libraries:
    18     (This step isn't necessary if you have the SDL binary distribution)
    20   Do the classic configure, with --disable-shared --enable-static and:
    22     Tos version (should run everywhere):
    23       --disable-threads
    24     Tos does not support threads.
    26     MiNT version (maybe Magic, only for multitasking OS):
    27       --disable-pthreads --enable-pth
    28     Mint and Magic may supports threads, so audio can be used with current
    29     devices, like Sun audio, or disk-writing support. Like Tos, interrupt
    30     audio without threads is more suited for Atari machines.
    32   Then you can make ; make install it.
    34 ==============================================================================
    35 II. Building the Simple DirectMedia Layer test programs:
    37   Do the classic configure, then make.
    39   Run them !
    41 ==============================================================================
    42 III.  Enjoy! :)
    44   If you have a project you'd like me to know about, or want to ask questions,
    45   go ahead and join the SDL developer's mailing list by sending e-mail to:
    49   and put "subscribe" into the subject of the message. Or alternatively you
    50   can use the web interface:
    54 ==============================================================================
    55 IV.  What is supported:
    57 Keyboard (GEMDOS, BIOS, GEM, Ikbd)
    58 Mouse (XBIOS, GEM, Ikbd)
    59 Video (XBIOS (Fullscreen), GEM (Windowed and Fullscreen))
    60 Timer (VBL vector, GNU pth library)
    61 Joysticks and joypads (Ikbd, Hardware)
    62 Audio (Hardware, XBIOS, GSXB, MCSN, STFA, /dev/audio if threads enabled)
    63 Threads (Multitasking OS only via GNU pth library)
    64 Shared object loader (using LDG library from
    65 Audio CD (MetaDOS)
    66 OpenGL (using Mesa offscreen rendering driver)
    68 - Dependent driver combinations:
    69 Video   Kbd     Mouse   Timer   Joysticks
    70 xbios   ikbd    ikbd    vbl(2)  ikbd
    71 xbios   gemdos  xbios   vbl(2)  xbios(3)
    72 xbios   bios    xbios   vbl(2)  xbios(3)
    73 gem     gem     gem(1)  vbl(2)  xbios(3)
    75 Audio   O/S     Misc
    76 dma8    All     Uses MFP Timer A interrupt
    77 xbios	TOS     Uses MFP Timer A interrupt
    78 xbios   MiNT    Uses MiNT thread
    79 xbios   Magic   Disabled
    80 stfa    All     Uses MFP interrupt
    81 mcsn	TOS     Uses MFP Timer A interrupt
    82 mcsn    MiNT    Uses MiNT thread
    83 mcsn    Magic   Disabled
    84 gsxb    All     Uses GSXB callback
    86 Joypad driver always uses hardware access.
    87 OpenGL driver always uses OSMesa.
    89 (1) GEM does not report relative mouse motion, so xbios mouse driver is used
    90 to report this type event. Under MiNT, using XBIOS mouse driver is not possible.
    92 (2) If you build SDL with threads using the GNU pth library, timers are
    93 supported via the pth library.
    95 (3) Redirecting XBIOS vectors does not work under MiNT, so it is disabled in
    96 this case.
    98 ==============================================================================
    99 V.  Environment variables:
   102 	Set to 'xbios' to force xbios video driver
   103 	Set to 'gem' to force gem video driver
   106 	Set to filename to load as OpenGL library, if you use SDL_GL_LoadLibrary()
   109 	Set to 'mint_gsxb' to force Atari GSXB audio driver
   110 	Set to 'mint_mcsn' to force Atari MCSN audio driver
   111 	Set to 'mint_stfa' to force Atari STFA audio driver
   112 	Set to 'mint_xbios' to force Atari Xbios audio driver
   113 	Set to 'mint_dma8' to force Atari 8 bits DMA audio driver
   114 	Set to 'audio' to force Sun /dev/audio audio driver
   115 	Set to 'disk' to force disk-writing audio driver
   118 	Set to 'ikbd' to force IKBD 6301 keyboard driver
   119 	Set to 'gemdos' to force gemdos keyboard driver
   120 	Set to 'bios' to force bios keyboard driver
   123 	Use any of these strings in the environment variable to enable or
   124 	disable a joystick:
   126 	'ikbd-joy1-[on|off]' for IKBD joystick on port 1 (hardware access)
   127 	'xbios-joy1-[on|off]' for IKBD joystick on port 1 (xbios access)
   128 	'porta-pad-[on|off]' for joypad on port A
   129 	'porta-joy0-[on|off]' for joystick 0 on port A
   130 	'porta-joy1-[on|off]' for joystick 1 on port A
   131 	'porta-lp-[on|off]' for lightpen on port A
   132 	'porta-anpad-[on|off]' for analog paddle on port A
   133 	'portb-pad-[on|off]' for joypad on port B
   134 	'portb-joy0-[on|off]' for joystick 0 on port B
   135 	'portb-joy1-[on|off]' for joystick 1 on port B
   136 	'portb-anpad-[on|off]' for analog paddle on port B
   138 	Default configuration is:
   139 		'ikbd-joy1-on' (if IKBD events driver enabled)
   140 		'xbios-joy1-on' (if gemdos/bios/gem events driver enabled)
   141 		'porta-pad-on portb-pad-on' (if available on the machine)
   143 	port[a|b]-[pad|joy?|lp|anpad]-* strings are mutually exclusives.
   144 	On such a port, you can only use a joypad OR 1 or 2 joysticks OR
   145 	a lightpen OR an analog paddle. You must disable joypad before
   146 	setting another controller.
   148 	The second joystick port on IKBD is used by the mouse, so not usable.
   149 	Another problem with the IKBD: mouse buttons and joystick fire buttons
   150 	are wired together at the hardware level, it means:
   151 		port 0                port 0           port 1
   152 		mouse left button  = joystick fire 0 = joystick fire 1
   153 		mouse right button = joystick fire 1 = joystick fire 0
   155 	Descriptions of joysticks/joypads:
   156 	- Joypads: 1 hat, 17 buttons (Atari Jaguar console-like).
   157 	- Joysticks: 1 hat, 1 button.
   158 	- Lightpen, analog paddles: 2 axis, 2 buttons. The 2 buttons are those
   159 	  affected to 1 button joysticks on the same port.
   161 ==============================================================================
   162 VI.  More informations about drivers:
   164 OpenGL:
   165 	The default is to use the Mesa offscreen driver (osmesa.ldg). If you want
   166 	to use an older OpenGL implementation, like mesa_gl.ldg or tiny_gl.ldg,
   167 	your program must use SDL_GL_LoadLibrary() to do so, and retrieve the
   168 	needed function pointers with SDL_LoadFunction(). In all cases, the OpenGL
   169 	context is taken care of by SDL itself, you just have to use gl* functions.
   171 	However, there is one OpenGL call that has a different prototype in the old
   172 	implementations: glOrtho(). In the old implementations, it has 6 float as
   173 	parameters, in the standard one, it has 6 double parameters. If you want
   174 	to compile testdyngl, or any other SDL program that loads its OpenGL
   175 	library, you must change the glOrtho() prototype used in this program. In
   176 	osmesa.ldg, you can retrieve a glOrtho() with double parameters, by
   177 	searching for the function "glOrtho6d".
   179 Xbios video:
   180 	Video chip is detected using the _VDO cookie.
   181 	Screen enhancers are not supported, but could be if you know how to
   182 	use them.
   184 	ST, STE, Mega ST, Mega STE:
   185 		320x200x4 bits, shades of grey, available only for the purpose
   186 		of testing SDL.
   187 	TT:
   188 		320x480x8 and 320x240x8 (software double-lined mode).
   189 	Falcon:
   190 		All modes supported by the current monitor (RVB or VGA).
   191 		BlowUp and Centscreen extended modes, ScreenBlaster 3 current mode.
   192 	Clones and any machine with monochrome monitor:
   193 		Not supported.
   195 Gem video:
   196 	Automatically used if xbios not available.
   198 	All machines:
   199 		Only the current resolution, if 8 bits or higher depth.
   201 IKBD keyboard, mouse and joystick driver:
   202 	Available if _MCH cookie is ST, Mega ST, STE, Mega STE, TT or Falcon.
   204 	Hades has an IKBD, but xbios is not available for video, so IKBD
   205 	driver is disabled.
   207 Gemdos and bios keyboard driver:
   208 	Available on all machines.
   210 Mouse and joystick xbios driver:
   211 	Available on all machines (I think).
   213 Joypad driver:
   214 	Available if _MCH cookie is STE or Falcon.
   216 PTH timer driver:
   217 	Available with multitasking OS.
   219 VBL timer driver:
   220 	Available on all machines (I think).
   222 Audio drivers:
   223 	Cookies _SND, MCSN, STFA and GSXB used to detect supported audio
   224 	capabilities.
   226 	STE, Mega STE, TT:
   227 		8 bits DMA (hardware access)
   228 		STFA, MCSN or GSXB driver if installed
   229 	Falcon:
   230 		8 bits DMA (hardware access)
   231 		Xbios functions
   232 		STFA, MCSN or GSXB driver if installed
   233 	Other machines:
   234 		STFA, MCSN or GSXB driver if installed
   236 	STFA driver:
   238 	GSXB driver:
   240 	MacSound driver:
   242 	MagicSound driver (MCSN,GSXB compatible):
   244 	X-Sound driver (GSXB compatible):
   247 -- 
   248 Patrice Mandin <>