Provided by: libsvga1-dev_1.4.3-24_i386 bug

NAME

       vga_ext_set - set and query several extended features

SYNOPSIS

       #include <vga.h>

       int vga_ext_set(unsigned what, ...);

DESCRIPTION

       sets and several extended features. Before trying to call vga_ext_set()
       you  should  check  if  it  is  available  in  vga_getmodeinfo(3)   for
       compatibility  with old svgalib versions. In addition, the availability
       of certain features will depend on the current graphics mode.

       However, the VGA_EXT_PAGE_OFFSET  and  VGA_EXT_FONT_SIZE  features  are
       features of the base module of svgalib and are always available if your
       version  of   svgalib   supports   them.   Actually   the   result   of
       vga_getmodeinfo(3)   shows   the   availability   of   enhancements  of
       vga_ext_set() in the  given  SVGA  graphics  mode.  Hence,  these  base
       features  may  be  supported  even  if svgalib does not admit it. Since
       version 1.2.13 you can check  vga_getmodeinfo(TEXT)  to  see  if  basic
       vga_ext_set()  functionality  is available. The VGA_EXT_PAGE_OFFSET and
       VGA_EXT_FONT_SIZE  calls  are  then  available  in  any  mode  even  if
       vga_getmodeinfo(3)  states  that  you  should not call vga_ext_set() at
       all.

       As of now, the following calls are defined:

   Query availability of features
       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_SET)
              returns an int with the i-th bit  set  if  i  is  a  valid  what
              parameter for vga_ext_set().

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_ACCEL)
              returns  an  integer  with the i-th bit set if i is a valid what
              parameter for  vga_accel(3).   For  nicer  code,  the  following
              integers are predefined to have a bit set in the right position:

              ACCELFLAG_FILLBOX,   ACCELFLAG_SCREENCOPY,   ACCELFLAG_PUTIMAGE,
              ACCELFLAG_DRAWLINE,  ACCELFLAG_SETFGCOLOR, ACCELFLAG_SETBGCOLOR,
              ACCELFLAG_SETTRANSPARENCY,                ACCELFLAG_SETRASTEROP,
              ACCELFLAG_PUTBITMAP,                 ACCELFLAG_SCREENCOPYBITMAP,
              ACCELFLAG_DRAWHLINELIST, ACCELFLAG_SETMODE, and  ACCELFLAG_SYNC.

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_ROP)
              returns  an  integer  as  VGA_AVAIL_ACCEL  does,  but  this time
              listing   the   vga_accel(3)    operations    which    obey    a
              vga_accel(ACCEL_SETRASTEROP, ...)  setting.

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_TRANSPARENCY)
              returns  an  integer  as  VGA_AVAIL_ACCEL  does,  but  this time
              listing   the   vga_accel(3)    operations    which    obey    a
              vga_accel(ACCEL_SETTRANSPARENCY, ...)  setting.

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_ROPMODES)
              returns  an  integer  with the i-th bit set if i is a valid mode
              parameter for a  vga_accel(ACCEL_SETRASTEROP,  mode)  call.  For
              example:

              if  (vga_ext_set(VGA_EXT_AVAILABLE,  VGA_AVAIL_ROPMODES) & (1 <<
              ROP_XOR))
                   vga_accel(ACCEL_SETRASTEROP, ROP_XOR);
              else
                   /* do something else */

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_TRANSMODES)
              returns an integer with the i-th bit set if i is  a  valid  mode
              parameter  for  a  vga_accel(ACCEL_SETTRANSPARENCY,  mode,  ...)
              call. The function lists only  the  supported  enable  functions
              (currently             ENABLE_TRANSPARENCY_COLOR             and
              ENABLE_BITMAP_TRANSPARENCY).  It is  assumed  the  corresponding
              disable functions will then exist as well.

       vga_ext_set(VGA_EXT_AVAILABLE, VGA_AVAIL_FLAGS)
              returns  an int with one bit on/off flags. Bits that are set are
              supported refer to special features which can be enabled in  the
              current mode.

   Operations with one bit flags
       A  certain  mode might have a special feature which can be turned on or
       off by the applications. These functions allow to handle such features.

       You  can  always  set  flags,  and their settings are remembered if not
       supported in the current mode. This is to avoid problems when switching
       VC’s.

       vga_ext_set(VGA_EXT_SET, int bitflags)
              set  all  flags that are set in bitflags, do not touch any other
              flags. Returns previous setting of all flags.

       vga_ext_set(VGA_EXT_CLEAR, int bitflags)
              clear all flags that are set in bitflags, do not touch any other
              flags. Returns previous setting of all flags.

       vga_ext_set(VGA_EXT_RESET, int bitflags)
              set  all  flags  to the corresponding bits of bitflags.  Returns
              previous setting of all flags.

   One bit flags for special features
       As of now, we only support

       VGA_CLUT8
              which is set  by  calling  vga_ext_set(VGA_EXT_SET,  VGA_CLUT8).
              This  makes  the  color lookup table for 16 and 256 color lookup
              table modes work with 8 bit per red, green, blue part instead of
              the ordinary 6 bits.

              As  of  now  this feature is only availabl for Mach32 cards with
              type 2 DAC’s.  8 bit per red, green, blue wide in all (even VGA)
              256   color  modes.  This  mean,  however,  that  all  calls  to
              vga_setpalette(3)  and  vga_setpalvec(3)  need  to  be   adjuste
              accordingly  as  well  as  that the interpretation of the return
              values of vga_getpalette(3) and vga_getpalvec(3) changes.

              The testaccel(6) demos makes use of this to show  a  smooth  256
              blue shades scale.

   Miscanellous features
       vga_ext_set(VGA_EXT_PAGE_OFFSET, int offset)
              for  all  following vga_set*page(n) calls (even those implicitly
              done by svgalib drawing functions) do vga_set*page(n  +  offset)
              instead.   This  is  very nice for drawing in an offscreen area.
              However, it requires the mode being able to use  more  than  one
              page    at    all    as    well    as    not    having    called
              vga_setlinearaddressing(3).

              A better approach would be to just use higher y values  for  all
              draw  operations  to  have them end up in offscreen regions that
              may be displayed later (cf.  vga_setdisplaystart(3)).

              The previously set value for VGA_EXT_PAGE_OFFSET (which defaults
              to 0 at startup) is returned.

       vga_ext_set(VGA_EXT_FONT_SIZE, int size)
              sets  the  size  of  the  buffer which the application passes to
              vga_gettextfont(3)  and  vga_puttextfont(3).   Old  versions  of
              svgalib  used  a  fixed size of 8192 which is still the default.
              Newer versions of  svgalib  use  a  larger  size  internally  to
              properly   support  the  extended  font  capabilities  of  newer
              kernels.

              Calling vga_ext_set(VGA_EXT_FONT_SIZE, 0) returns  the  size  of
              the  internal  buffers of svgalib. It is recommended to use this
              (or a larger size) for any font (re)storing application. If this
              differs   from   the   size  of  the  applications  buffers  set
              vga_gettextfont(3) and vga_puttextfont(3) truncate and  zero-pad
              all buffers accordingly.

              Otherwise the previously set buffer size is returned.

SEE ALSO

       svgalib(7),   vgagl(7),   libvga.config(5),   accel(6),   testaccel(6),
       vga_setpalette(3),         vga_setpalvec(3),         vga_getpalette(3),
       vga_getpalvec(3),  vga_setlinearaddressing(3),  vga_setdisplaystart(3),
       vga_setpage(3),        vga_setreadpage(3),         vga_setwritepage(3),
       vga_gettextfont(3), vga_puttextfont(3).

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.