Drivers can support the XFree86 Direct Graphics Architecture (DGA) by
filling out a structure of function pointers and a list of modes and
passing them to DGAInit.
Bool DGAInit(ScreenPtr pScreen, DGAFunctionPtr funcs,
DGAModePtr modes, int num)
/** The DGAModeRec **/
typedef struct {
int num;
DisplayModePtr mode;
int flags;
int imageWidth;
int imageHeight;
int pixmapWidth;
int pixmapHeight;
int bytesPerScanline;
int byteOrder;
int depth;
int bitsPerPixel;
unsigned long red_mask;
unsigned long green_mask;
unsigned long blue_mask;
int viewportWidth;
int viewportHeight;
int xViewportStep;
int yViewportStep;
int maxViewportX;
int maxViewportY;
int viewportFlags;
int offset;
unsigned char *address;
int reserved1;
int reserved2;
} DGAModeRec, *DGAModePtr;
num
Can be ignored. The DGA DDX will assign these numbers.
mode
A pointer to the DisplayModeRec for this mode.
flags
The following flags are defined and may be OR'd together:
DGA_CONCURRENT_ACCESS
Indicates that the driver supports concurrent graphics
accelerator and linear framebuffer access.
DGA_FILL_RECT
DGA_BLIT_RECT
DGA_BLIT_RECT_TRANS
Indicates that the driver supports the FillRect, BlitRect
or BlitTransRect functions in this mode.
DGA_PIXMAP_AVAILABLE
Indicates that Xlib may be used on the framebuffer.
This flag will usually be set unless the driver wishes
to prohibit this for some reason.
DGA_INTERLACED
DGA_DOUBLESCAN
Indicates that these are interlaced or double scan modes.
imageWidth
imageHeight
These are the dimensions of the linear framebuffer
accessible by the client.
pixmapWidth
pixmapHeight
These are the dimensions of the area of the
framebuffer accessible by the graphics accelerator.
bytesPerScanline
Pitch of the framebuffer in bytes.
byteOrder
Usually the same as
pScrn->imageByteOrder.
depth
The depth of the framebuffer in this mode.
bitsPerPixel
The number of bits per pixel in this mode.
red_mask
green_mask
blue_mask
The RGB masks for this mode, if applicable.
viewportWidth
viewportHeight
Dimensions of the visible part of the framebuffer.
Usually mode->HDisplay and
mode->VDisplay.
xViewportStep
yViewportStep
The granularity of x and y viewport positions that
the driver supports in this mode.
maxViewportX
maxViewportY
The maximum viewport position supported by the
driver in this mode.
viewportFlags
The following may be OR'd together:
DGA_FLIP_IMMEDIATE
The driver supports immediate viewport changes.
DGA_FLIP_RETRACE
The driver supports viewport changes at retrace.
offset
The offset into the linear framebuffer that corresponds to
pixel (0,0) for this mode.
address
The virtual address of the framebuffer as mapped by the driver.
This is needed when DGA_PIXMAP_AVAILABLE is set.
/** The DGAFunctionRec **/
typedef struct {
Bool (*OpenFramebuffer)(
ScrnInfoPtr pScrn,
char **name,
unsigned char **mem,
int *size,
int *offset,
int *extra
);
void (*CloseFramebuffer)(ScrnInfoPtr pScrn);
Bool (*SetMode)(ScrnInfoPtr pScrn, DGAModePtr pMode);
void (*SetViewport)(ScrnInfoPtr pScrn, int x, int y, int flags);
int (*GetViewport)(ScrnInfoPtr pScrn);
void (*Sync)(ScrnInfoPtr);
void (*FillRect)(
ScrnInfoPtr pScrn,
int x, int y, int w, int h,
unsigned long color
);
void (*BlitRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty
);
void (*BlitTransRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty,
unsigned long color
);
} DGAFunctionRec, *DGAFunctionPtr;
Bool OpenFramebuffer (pScrn, name, mem, size, offset, extra)
OpenFramebuffer() should pass the client everything
it needs to know to be able to open the framebuffer. These
parameters are OS specific and their meanings are to be interpreted
by an OS specific client library.
name
The name of the device to open or NULL if
there is no special device to open. A NULL
name tells the client that it should open whatever device
one would usually open to access physical memory.
mem
The physical address of the start of the framebuffer.
size
The size of the framebuffer in bytes.
offset
Any offset into the device, if applicable.
flags
Any additional information that the client may need.
Currently, only the DGA_NEED_ROOT flag is
defined.
void CloseFramebuffer (pScrn)
CloseFramebuffer() merely informs the driver (if it
even cares) that client no longer needs to access the framebuffer
directly. This function is optional.
Bool SetMode (pScrn, pMode)
SetMode() tells the driver to initialize the mode
passed to it. If pMode is NULL,
then the driver should restore the original pre-DGA mode.
void SetViewport (pScrn, x, y, flags)
SetViewport() tells the driver to make the upper
left-hand corner of the visible screen correspond to coordinate
(x,y) on the framebuffer. Flags
currently defined are:
DGA_FLIP_IMMEDIATE
The viewport change should occur immediately.
DGA_FLIP_RETRACE
The viewport change should occur at the
vertical retrace, but this function should
return sooner if possible.
The (x,y) locations will be passed as the client
specified them, however, the driver is expected to round these
locations down to the next supported location as specified by the
xViewportStep and yViewportStep
for the current mode.
int GetViewport (pScrn)
GetViewport() gets the current page flip status.
Set bits in the returned int correspond to viewport change requests
still pending. For instance, set bit zero if the last SetViewport
request is still pending, bit one if the one before that is still
pending, etc.
void Sync (pScrn)
This function should ensure that any graphics accelerator operations
have finished. This function should not return until the graphics
accelerator is idle.
void FillRect (pScrn, x, y, w, h, color)
This optional function should fill a rectangle
w × h located at
(x,y) in the given color.
void BlitRect (pScrn, srcx, srcy, w, h, dstx, dsty)
This optional function should copy an area
w × h located at
(srcx,srcy) to location (dstx,dsty).
This function will need to handle copy directions as appropriate.
void BlitTransRect (pScrn, srcx, srcy, w, h, dstx, dsty, color)
This optional function is the same as BlitRect except that pixels
in the source corresponding to the color key color
should be skipped.
