Ubuntu Manpage: vga_getmodeinfo - returns pointer to mode information structure for a mode

Provided by: libsvga1-dev_1.4.3-33_amd64

NAME

       vga_getmodeinfo - returns pointer to mode information structure for a mode

SYNOPSIS

       #include <vga.h>

       vga_modeinfo *vga_getmodeinfo(int mode );

DESCRIPTION

The function returns a pointer to a statical allocated mode information structure which is
filled out with details for a video mode mode.

#include <vga.h> defines vga_modeinfo as

typedef struct {
int width;
int height;
int bytesperpixel;
int colors;
int linewidth;
int maxlogicalwidth;
int startaddressrange;
int maxpixels;
int haveblit;
int flags;
/* Extended fields, not always available: */
int chiptype;
int memory;
int linewidth_unit;
char *linear_aperture;
int aperture_size;
void (*set_aperture_page) (int page);
void *extensions;
} vga_modeinfo;

If the given mode is out of range, NULL is returned. Beware, even when vga_getmodeinfo()
returns details about a certain mode, you must check if it is currently available (may
depend on memory size and other details) with vga_hasmode (3).

The fields meaning in detail:

Basic mode details
width Width of mode in pixels.

height Height of mode in pixel lines.

bytesperpixel
Bytes per pixel. This is 1, 2, 3, or 4 (for 256, 32K & 64K, 16M, 16M$ modes) and 0
for planar VGA modes.

linewidth
Logical scanline width in bytes. This is the memory offset between two pixels above
each other in two adjacent screen lines. It is not valid to assume that linewidth
== width * bytesperpixel in general!

colors The number of colors which you can display simultaneously 2, 16, 256, 32768, 65536,
or 16777216. Generally 16 and 256 mean that a color lookup table is used. 2 means
that only black/white is used and the others use some high/true color mode.

Possible modifications of the memory layout
maxlogicalwidth
The maximum logical scanline width (in bytes) which you can set for this mode with
vga_setlogicalwidth(3) while still expecting a perfect screen image.

startaddressrange
Mask of changeable bits of start address (in pixels). All bits zero in
startaddressrange must also be zero in a call to vga_setdisplaystart(3) when you
want to avoid noisy video signals.

Memory size
maxpixels
Maximum number of pixels that will fit in a logical screen (depends on video
memory).

Further, advanced capabilities
haveblit
Indicates whether the following bitblit functions are available. It is a logical or
of the following predefined values (which each have only one bit set).

HAVE_BITBLIT
has vga_bitblt(3) old style accelerator function.

HAVE_FILLBLIT
has vga_fillblt(3) old style accelerator function.

HAVE_IMAGEBLIT
has vga_imageblt(3) old style accelerator function.

HAVE_HLINELISTBLIT
has vga_hlinelistblt(3) old style accelerator function.

HAVE_BLITWAIT
has vga_blitwait(3) old style accelerator function.

flags Miscellaneous flags. It is a logical or of the following predefined values (which
each have only one bit set).

HAVE_RWPAGE
vga_setreadpage(3) and vga_setwritepage(3) are available in this mode.

IS_INTERLACED
Mode is interlaced, which means it will tend to flicker and the user might
be happier if the application chooses another mode.

IS_MODEX
Mode user mode X like memory layout (planar 256 colors VGA mode). See
vga_setmodeX(3) for some explanations.

IS_DYNAMICMODE
Dynamically loaded mode. This mode was defined in /etc/vga/libvga.conf by
the user. He will probably prefer its usage. However, usually this should be
of no interest to the user.

CAPABLE_LINEAR
Mode can be set to linear addressing with vga_setlinearaddressing(3).

IS_LINEAR
Linear addressing is already enabled for this mode.

EXT_INFO_AVAILABLE
The extended fields in this information structure are set to sensible
information. If EXT_INFO_AVAILABLE is not set you should even not access
these fields as you might have encountered an old version of svgalib and the
fields migth actually not have been allocated at all.

RGB_MISORDERED
For 16M4 modes it means that the 4 bytes per pixel actually mean 0BGR rather
than BGR0 as per default. For 16M mode it means that the 3 bytes actually
mean RGB instead of BGR.

The first is a general limitation of Mach32, the latter one of Mach32 with a
ramdac of type 4. The vga_ drawing functions takes this into account.

HAVE_EXT_SET
A vga_ext_set(3) is available and can be called.

Extended mode information
You must check for EXT_INFO_AVAILABLE in flags before trying to access these values.

chiptype
the chiptype that was detected/set. This specifies a subtype of the current
vga_getchipset(3) setting whose value depends on the chipset. It should be only
used for debugging or internally.

memory memory available on the SVGA card in KB.

linewidth_unit
use only a multiple of this value for set_logicalwidth(3) or set_displaystart(3) to
ensure graceful alignment of lines onto the vga memory in this mode and for
noiseless video signals.

linear_aperture
ptr to a mmaped secondary linear framebuffer (not related to the use of
vga_setlinearaddressing(3)) (NULL if unavailable)

aperture_size
size of the secondary framebuffer in KB. 0 if unavailable.

set_aperture_page
a function taking an int as parameter to select a page in the framebuffer addressed
by read/writes to this memory arey (if aperture_size < memory.

extensions
pointer to additional, internal, chipset specific info (contents of the EEPROM for
Mach32 driver.)

The vgatest(6) demo displays most of this info for all supported modes.

AUTHOR

       This manual page was edited by Michael Weller  <eowmob@exp-math.uni-essen.de>.  The  exact
       source of the referenced function as well as of the original documentation is unknown.

       It  is  very  likely  that  both  are  at  least to some extent are due to Harm Hanemaayer
       <H.Hanemaayer@inter.nl.net>.

       Occasionally this might be wrong. I hereby asked to be excused by the original author  and
       will  happily  accept  any  additions  or corrections to this first version of the svgalib
       manual.

NAME

SYNOPSIS

DESCRIPTION

SEE ALSO

AUTHOR