Intel 815 manual Setupblt

Models: 815

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Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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12.2.1.SETUP_BLT

The setup instruction supplies common setup information including clipping coordinates used exclusively with the following 3 instructions:

1.PIXEL_BLT (PB) - 1 pixel write with the coordinate and solid pattern supplied for each pixel to be written. No non-solid patterns nor source operands are allowed.

2.SCANLINE_BLT (SLB) - 1 scan line of color or mono pattern and destination are the only operands allowed.

3.TEXT_BLT (TB) - linear monochrome source either through the instruction stream or from graphics memory (not cacheable) and destination are the only operands allowed. Source copy is the only supported operation. The raster operation field must = CCh.

Clipping addresses and coordinates are inclusive. (The BLT Engine performs a trivial reject for all 3 BLT instructions listed above before performing any accesses. If any pixels are included within the clipping rectangle, then it performs every access, but deasserts the byte enables for the pixels that are clipped.)

The source operand (TEXT_BLT only) never overlaps with the destination. Therefore, X and Y direction is always positive (left to right and top to bottom). Only a positive destination pitch is allowed.

All fields above indicate which instructions require valid state. These are the only instructions that require that state be saved between instructions. There are 4 dedicated registers to contain the state for these 3 instructions. All other BLTs use a temporary version of these. The 4 double word registers are: DW1 (Control), DW5 (Foreground color), DW6 (Background color), and DW7 (Pattern address). The ClipRect registers do not need to be saved since they are never used by the interrupt ring buffer.

Note: The Mono source transparency mode flag is maintained (although it is always set to one in current driver operation).

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Page 164
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Intel 815 manual Setupblt