Intel 815 12.3.14. BR13-BLT Raster OP, Control, and Destination Pitch, Increment/Decrement Select

Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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12.3.14. BR13—BLT Raster OP, Control, and Destination Pitch

Memory Offset Address:						40034h
Default:						0000 xxxx
Attributes:						RO; DWord accessible
31	30		29	28	27	26	25	24	23	16
Sol		X	Mon	Mon	Src	Dyn	Dynamic
Pat		Dir	Src	Pat	Sel	Col	Color			Raster Operation Select
Sel			Trans	Trans	Mode	En	Depth
15	14		13							0
Reserved.							Destination Pitch (Offset)
Must be
	Zero
		Bit						Descriptions

31Solid Pattern Select. This bit applies only when the pattern data is monochrome. This bit determines whether or not the BLT Engine actually performs read operations from the frame buffer to load the pattern data. Use of this feature to prevent these read operations can increase BLT Engine performance, if use of the pattern data is indeed not necessary. The BLT Engine is configured to accept either monochrome or color pattern data via the opcode field.

0 = This causes normal operation with regard to the use of the pattern data. The BLT Engine proceeds with the process of reading the pattern data, and the pattern data is used as the pattern operand for all bit-wise operations.

1 = The BLT Engine forgoes the process of reading the pattern data, the presumption is made that all of the bits of the pattern data are set to 0, and the pattern operand for all bit-wise operations is forced to the background color specified in the Color Expansion Background Color Register.

30X Increment/Decrement Select.

0 = The bytes corresponding to the pixels within each scan line of data are written to the destination starting with the bytes corresponding to the left-most pixel of each scan line at the destination being the first to be written, and then proceeding in a rightward direction toward the right-most pixel.

1 = The bytes corresponding to the pixels within each scan line of data are written to the destination starting with the bytes corresponding to the right-most pixel of each scan line at the destination being the first to be written, and then proceeding in a leftward direction toward the left-most pixel.

29Monochrome Source Transparency Mode. This bit applies only when the source data is in monochrome. This bit determines whether or not the byte(s) at the destination corresponding to the pixel to which a given bit of the source data also corresponds will actually be written if that source data bit has the value of 0. This feature can make it possible to use the source as a transparency mask. The BLT Engine is configured to accepted either monochrome or color source data via the opcode field.

0 = This causes normal operation with regard to the use of the source data. Where a bit in the source data has the value of 0, the color specified in the background color register is used as the source operand in the bit-wise operation for the pixel corresponding to the source data bit, and the bytes at the destination corresponding to that pixel are written with the result.

1 = Where a bit in the source data has the value of 0, the byte(s) at the destination corresponding to the pixel to which the source data bit also corresponds are simply not written, and the data at those byte(s) at the destination are allowed to remain unchanged.

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