NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
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Revision V1.30
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zeros are either expanded to a pixel of background color or transparent. Note that color/font expansion
can be performed using X/Y addressing only.
To transfer data quickly from display memory to system memory, the host may set up a host read BLT
to let the resultant destination data go to the system memory. Note that only source copy operation
(SRCCOPY) is available in a host read BLT.
HostBLT is executed through eight 32-bit MMIO data ports for bit block data transfer. The host must
perform 32-bit word-aligned accesses when writing data to, or reading data from the Graphics Engine.
Pattern BLT
5.28.5.3
The Pattern BLT is used to accelerate filling of an area of arbitrary size with a repeating pattern in
color or mono, and any raster operation may be involved if necessary. The pattern size is 8
8 pixels,
chosen for compatibility with Microsoft Windows. Note that all patterns are always aligned to the top-
left corner of display memory, but not to the destination area, and the pattern source must be aligned
on a boundary, which is equal to the size of the destination.
The 8
8 pattern may be color or monochrome. In the color case, the host first writes the desired
pattern to off-screen memory of the frame buffer in a linear fashion. When BitBLT involving pattern is
executed, the Graphics Engine will fetch the corresponding row pattern from the off-screen memory
and then repetitively copies it to the destination area.
In the monochrome case, the host first writes the desired mono pattern to the internal 8-byte pattern
register. The Graphics Engine then repetitively copies it to the destination area, with all ones in the
pattern being expanded to a pixel of foreground color and all zeros being either expanded to a pixel of
background color or transparent. Note that only X/Y addressing can be used for mono Pattern BLT.
Color/Font Expanding BLT
5.28.5.4
To further accelerate the color/font expanding operation, the host may first write the monochrome
bitmap to off-screen memory of the frame buffer, then sets up a Color/Font Expanding BLT. In this
kind of BitBLT, the Graphics Engine fetches the monochrome source data from off-screen memory of
the frame buffer, expands it to pixels, and then writes them to the desired destination area. All ones in
the source are expanded to a pixel of foreground color and all zeros are either expanded to a pixel of
background color or transparent. Note that X/Y addressing fashion is always used in Color/Font
Expanding BLT.
Transparent BLT
5.28.5.5
During a BitBLT operation, a certain area of destination may be transparent with the rest being
opaque. Monochrome and color transparency are all supported in this chip. In monochrome
transparency, either source or pattern data may control the transparency of BitBLT, with all ones being
expanded to a pixel of foreground color and all zeros being transparent.
In color transparency, source and destination transparency are both supported, with only one being in
effect at a time. Transparent source colors (a color, or color space) do not overwrite the background
destination, while only transparent destination colors may be overwritten by the source.
Color/Font Expansion
5.28.5.6
Color/Font Expansion is used to expand a monochrome data to a full depth color pixel (including
8/16/32 bit-per-pixel color) with transparency, which greatly accelerates the rendering of text, icons,
and other monochrome source objects.