M69000 Asiliant Technologies, M69000 Datasheet - Page 352

• Manufacturer Part Number: M69000
• Manufacturer: Asiliant Technologies

Specifications of M69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

BitBLT Operation
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and Pattern/Source Expansion Background Color Register (BR01). Depending upon the setting of bit 27 in
the Monochrome Source Control Register (BR03), these same two registers may also specify the
foreground and background colors to be used in the color expansion of the source data.
Destination Data
If the destination is within the frame buffer, then there are actually two different types of “destination data”:
the graphics data already residing at the location that is designated as the destination, and the data that is
to be written into that very same location as a result of a BitBLT operation. If, however, the destination is
selected so that the BitBLT engine is to provide its output to the host CPU, then the destination data
provided to the host CPU is the only kind there is.
Blocks of destination data to be read from and written to the destination may be either contiguous or
discontiguous. All data written to the destination will have the color depth to which the BitBLT engine has
been set. It is presumed that any data already existing at the destination which will be read by the BitBLT
engine will also be of this same color depth — the BitBLT engine neither reads nor writes monochrome
destination data.
Bit 11 of the BitBLT Control Register (BR04) is used to specify whether the destination data is to be written
to a location within the frame buffer, or is to be provided to the host CPU. If the destination is within the
frame buffer, the Destination Address Register (BR07) is used to specify the address of the destination as
an offset from the beginning of the frame buffer at which the destination location begins. Otherwise, only
bits 2-0 of the Destination Address Register (BR07) are used, and there purpose is to specify which byte in
the first quadword of destination data provided to the host CPU is the first byte of actual destination data.
To accommodate discontiguous destination data, the Source and Destination Offset Register (BR00) can
be used to specify the offset in bytes from the beginning of one scan line’s worth of destination data to the
next. Otherwise, if the destination data is contiguous, then an offset equal to the length of a scan line’s worth
of destination data should be specified.
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69000 Databook
Subject to Change Without Notice
Revision 1.3 8/31/98