Intel® 945G/945GZ/945GC/ 945P/945PL Express Chipset Family ...

10.5.6 2D Engine
Functional Description
The GMCH contains BLT functionality, and an extensive set of 2D instructions. To take
advantage of the 3D drawing engine’s functionality, some BLT functions (such as, Alpha BLTs,
arithmetic (bilinear) stretch BLTs, rotations, transposing pixel maps, limited color space
conversion, and DIBs) make use of the 3D renderer.
10.5.6.1 GMCH VGA Registers
The 2D registers are a combination of registers defined by IBM when the Video Graphics Array
(VGA) was first introduced and others that Intel has added to support graphics modes that have
color depths, resolutions, and hardware acceleration features that go beyond the original VGA
standard.
10.5.6.2 Logical 128-bit Fixed BLT and 256 Fill Engine
Use of this BLT engine accelerates the Graphical User Interface (GUI) of Microsoft Windows*
operating systems. The 128-bit GMCH BLT engine provides hardware acceleration of block
transfers of pixel data for many common Windows operations. The term BLT refers to a block
transfer of pixel data between memory locations. The BLT engine can be used for the following:
� Move rectangular blocks of data between memory locations
� Data Alignment
� Perform logical operations (raster ops)
The rectangular block of data does not change as it is transferred between memory locations. The
allowable memory transfers are between: cacheable system memory and frame buffer memory,
frame buffer memory and frame buffer memory, and within system memory. Data to be
transferred can consist of regions of memory, patterns, or solid color fills. A pattern will always
be 8x8 pixels wide and may be 8, 16, or 32 bits per pixel.
The GMCH BLT engine has the ability to expand monochrome data into a color depth of 8, 16, or
32 bits. BLTs can be either opaque or transparent. Opaque transfers move the data specified to the
destination. Transparent transfers compare destination color to source color and write according
to the mode of transparency selected.
Data is horizontally and vertically aligned at the destination. If the destination for the BLT
overlaps with the source memory location, the GMCH can specify which area in memory to begin
the BLT transfer. Hardware is included for all 256 raster operations (Source, Pattern, and
Destination) defined by Microsoft, including transparent BLT.
The GMCH has instructions to invoke BLT and stretch BLT operations, permitting software to set
up instruction buffers and use batch processing. The GMCH can perform hardware clipping
during BLTs.
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