b9ca8e8378
allow the shadow framebuffer (softscreen) to be used with any vga driver, not just vesa. this removes the ugly scr->paddr = 0 hack employed by vesa driver to force softscreen and adds a softscreen vgactl message that can switch the feature on and off at runtime. softscreen can greatly improve graphics performance when bus reads are slow even tho it disables hardware acceleration.
271 lines
5.1 KiB
Plaintext
271 lines
5.1 KiB
Plaintext
.TH VGA 3
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.SH NAME
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vga \- VGA controller device
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.SH SYNOPSIS
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.nf
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.B bind #v /dev
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.B /dev/vgabios
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.B /dev/vgactl
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.B /dev/vgaovl
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.B /dev/vgaovlctl
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.fi
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.SH DESCRIPTION
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The VGA device allows configuration of a graphics controller
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on a PC.
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.B Vgactl
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allows control over higher-level settings such as display height, width, depth,
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controller and hardware-cursor type.
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Along with the I/O-port registers
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provided by
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.IR arch (3),
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it is used to implement configuration and setup of VGA controller cards.
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This is usually performed by
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.IR vga (8).
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.PP
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.B Vgabios
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provides read-only access to the low 640kB of memory,
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where the VGA and other BIOS ROMs are located.
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.PP
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Writing strings to
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.B vgactl
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configures the VGA device.
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The following are valid commands.
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.TP
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.BI size " X" x Y x "Z chan"
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Set the size of the screen image to be
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.I X
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pixels wide
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and
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.I Y
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pixels high.
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Each pixel is
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.I Z
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bits as specified by
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.IR chan ,
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whose format is described in
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.IR image (6).
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.TP
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.BI actualsize " X" x Y
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Set the physical size of the display to be
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.I X
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pixels wide by
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.I Y
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pixels high.
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This message is optional;
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it is used to implement panning and to accommodate
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displays that require the in-memory screen image
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to have certain alignment properties.
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For example, a 1400x1050 screen with a 1408x1050 in-memory image
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will use
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.B "size 1408x1050
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but
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.BR "actualsize 1400x1050" .
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.TP
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.BI panning " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable panning in a virtual screen.
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If panning is on and the screen's
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.B size
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is larger than its
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.BR actualsize ,
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the displayed portion of the screen will pan to follow the mouse.
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Setting the panning mode after the first attach of the
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.B #i
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driver has no effect.
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.TP
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.BI type " ctlr"
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Set the type of VGA controller being used.
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.I Ctlr
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is one of
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.BR ark200pv ,
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.BR clgd542x ,
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.BR clgd546x ,
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.BR ct65545 ,
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.BR cyber938x ,
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.BR hiqvideo ,
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.BR mach64xx ,
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.BR mga2164w ,
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.BR neomagic ,
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.BR nvidia ,
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.BR s3 ,
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and
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.BR t2r4 .
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.IP
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Note that this list does not indicate the full set of VGA chips
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supported. For example,
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.B s3
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includes the 86C801/5, 86C928, Vision864, and Vision964.
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It is the job of
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.IR vga (8)
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to recognize which particular chip is being used and to initialize it
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appropriately.
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.TP
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.BI hwgc " gc"
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Set the type of hardware graphics cursor being used.
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.I Gc
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is one of
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.BR ark200pvhwgc ,
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.BR bt485hwgc ,
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.BR clgd542xhwgc ,
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.BR clgd546xhwgc ,
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.BR ct65545hwgc ,
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.BR cyber938xhwgc ,
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.BR hiqvideohwgc ,
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.BR mach64xxhwgc ,
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.BR mga2164whwgc ,
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.BR neomagichwgc ,
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.BR nvidiahwgc ,
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.BR rgb524hwgc ,
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.BR s3hwgc ,
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.BR t2r4hwgc ,
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.BR tvp3020hwgc ,
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and
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.BR tvp3026hwgc .
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A value of
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.B off
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disables the cursor.
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There is no software cursor.
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.TP
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.BI palettedepth " d"
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Set the number of bits of precision used by the
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VGA palette to
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.IR d ,
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which must be either
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.B 6
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or
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.BR 8 .
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.TP
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.B blank
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Blank the screen.
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This consists of setting the hardware
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color map to all black as well as, on some controllers, setting the
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VGA hsync and vsync signals so as to turn off
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VESA DPMS-compliant monitors.
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The screen also blanks after 30 minutes of inactivity.
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The screen can be unblanked by moving the mouse.
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.TP
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.BI blanktime " minutes"
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Set the timeout before the
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screen blanks; the default is 30 minutes.
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If
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.I minutes
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is zero, blanking is disabled.
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.TP
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.BI hwaccel " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable whether hardware acceleration
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(currently for rectangle filling and moving)
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used by the graphics engine.
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The default setting is
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.BR on .
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.TP
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.BI softscreen " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable shadow framebuffer to reduce
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slow bus reads. Enabling
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.BI softscreen
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disables hardware acceleration. The default setting is
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.BR off
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except for the
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.BR vesa
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driver.
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.TP
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.BI hwblank " mode"
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Depending on whether
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.I mode
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is
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.B on
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or
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.BR off ,
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enable or disable the use of DPMS blanking
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(see
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.B blank
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above).
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.TP
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.BI linear " size align"
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Use a linear screen aperture of size
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.I size
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aligned on an
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.IR align -byte
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boundary.
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.TP
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.B drawinit
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Initialize the graphics hardware.
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This must be sent after setting the
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.BR type .
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.PP
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Reading
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.B vgactl
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returns the current settings, one per line.
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.PP
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Some VGA cards support overlay graphics.
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Writing strings to
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.B vgaovlctl
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configures such cards.
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The following are valid overlay control commands:
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.TP
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.BI openctl
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opens the overlay device.
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.TP
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.BI configure " w h format"
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allocates resources inside the driver to support an overlay area
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of width
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.I w
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and height
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.I h
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pixels. Currently, the only supported
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.I format
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is
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.B YUYV
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packed.
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In
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.B YUYV
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two pixels are encoded by their separate Y values
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and their combined U and V values.
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The size of the two pixels is 32 bits.
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.TP
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.BI enable " x y w h"
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enables drawing data on the display through the overlay mode. The data
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is drawn at position
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.IR x , y
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and has a width and height of
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.IR w , h
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respectively.
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.TP
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.BI closectl
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terminates overlay control.
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.PP
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Overlay data can be written to
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.BR vgaovl .
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.SH EXAMPLES
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The following disables hardware acceleration.
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.IP
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.EX
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echo hwaccel off > /dev/vgactl
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.EE
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.SH SOURCE
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.B /sys/src/9/pc/devvga.c
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.SH SEE ALSO
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.IR arch (3),
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.IR vga (8)
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.SH BUGS
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The hardware graphics cursor on the
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.B et4000
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does not work in 2x8-bit mode.
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