Intel 815 Manuel D’Utilisation
Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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13.3.1. Motion Vector Format
The motion vectors provided in the GFXBLOCK instruction have the following format.
DWord Bits
Description
0 31:16
Horizontal Motion Vector Value: The value is signed 2’s complement fixed point
with the following formats, depending on the Motion Vector Precision bits. The
range defines the clamp boundaries for the values.
with the following formats, depending on the Motion Vector Precision bits. The
range defines the clamp boundaries for the values.
Precision Format
Range
1
/
2
pixel
S14.1
[-1024.0–1023.5]
1
/
4
pixel
S13.2
[-1024.0–1023.75]
1
/
8
pixel
S12.3
[-1024.0–1023.875]
15:0
Vertical Motion Vector Value: The value is signed 2’s complement fixed point with
the following formats, depending on the Motion Vector Precision bits. The range
defines the clamp boundaries for the values.
the following formats, depending on the Motion Vector Precision bits. The range
defines the clamp boundaries for the values.
Precision Format
Range
1
/
2
pixel
S14.1
[-1024.0–1023.5]
1
/
4
pixel
S13.2
[-1024.0–1023.75]
1
/
8
pixel
S12.3
[-1024.0–1023.875]
13.4.
Non-pipelined State Variables
The GMCH does not optimize on state variables that change infrequently. ISVs are asked to group
polygons for state changes for performance reasons. In the GMCH, the following state variables will not
be pipelined:
polygons for state changes for performance reasons. In the GMCH, the following state variables will not
be pipelined:
Z_BIAS[7:0], FOG_CLR[23:0], ALPHA_REF[7:0], ALPHA_FUNC[2:0], KILL_PIXEL,
COLOR_KEYH[15:0], COLOR_KEYL[15:0], COLOR_INDEX[7:0], DEST_BUFFER_VARIABLES,
DRAWING_RECTANGLE_INFO, SCISSOR_RECTANGLE_INFO.
COLOR_KEYH[15:0], COLOR_KEYL[15:0], COLOR_INDEX[7:0], DEST_BUFFER_VARIABLES,
DRAWING_RECTANGLE_INFO, SCISSOR_RECTANGLE_INFO.
These have been grouped appropriately into packets that tell the instruction parser that these are non-
pipelined state variables. The 3D pipeline will be flushed up to and including the Color Calculator stage
before these state variables are updated. The pixel cache or the streamers do not need to be flushed for
state change. It is important for the application to group these changes into one pipeline to minimize
performance impact. This optimization has no software impact other than a slight performance impact.
pipelined state variables. The 3D pipeline will be flushed up to and including the Color Calculator stage
before these state variables are updated. The pixel cache or the streamers do not need to be flushed for
state change. It is important for the application to group these changes into one pipeline to minimize
performance impact. This optimization has no software impact other than a slight performance impact.