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vga_getmodeinfo(3)            Svgalib User Manual           vga_getmodeinfo(3)

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.

SEE ALSO
       svgalib(7), vgagl(7), libvga.config(5), vgatest(6), vga_hasmode(3),
       vga_init(3), vga_setmode(3), vga_getcurrentmode(3),
       vga_getdefaultmode(3), vga_lastmodenumber(3), vga_getmodename(3),
       vga_getmodenumber(3), vga_setlogicalwidth(3), vga_bitblt(3),
       vga_fillblt(3), vga_imageblt(3), vga_hlinelistblt(3), vga_blitwait(3),
       vga_setmodeX(3), vga_getchipset(3), vga_ext_set(3),
       vga_setlinearaddressing(3)

AUTHOR
       This manual page was edited by Michael Weller <[email protected]
       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 <[email protected]>.

       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.

Svgalib (>= 1.2.11)              27 July 1997               vga_getmodeinfo(3)
Command Section