B69000 Asiliant Technologies, B69000 Datasheet - Page 291

• Manufacturer Part Number: B69000
• Manufacturer: Asiliant Technologies

Specifications of B69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

17-8
17
16-15
&+,36
Monochrome Pattern Write-Masking
Color Transparency Select
69000 Databook
16 15
Note: This bit applies only when the pattern data is monochrome (determined by bit 18 of
this register).
This bit enables a form of per-pixel write-masking in which monochrome pattern data is
used as a pixel mask that controls which pixels at the destination will be written to by the
BitBLT engine.
0: This disables the use of monochrome pattern data as a write mask, allowing normal
operation of the BitBLT engine with regard to the use of monochrome pattern data.
1: Wherever a bit in monochrome pattern data carries the value of 0 the byte(s) of the
corresponding pixel at the destination are NOT written, thereby preserving any data already
carried by those bytes.
These 2 bits are used to select the type of color transparency to be performed.
When color transparency is enabled by setting bit 14 of this register to 1, the color value
carried within bits 23-0 of either BR01 or BR09 is used as a key color to mask the writing
of pixel data to the destination on a per-pixel basis. Before each pixel at the destination is
written, a comparison is made between this key color and another color, and whether or not
that given pixel at the destination will actually be written depends upon the result of that
comparison.
Whether BR01 or BR09 is used to supply the key color depends on the setting of bit 27 of
BR03 since the same register that is used to supply the key color for color transparency
also happens to be used to supply the background color for monochrome-to-color
expansion. Also, depending on the type of color transparency selected, the other color
value to which the key color is compared may be the color value resulting from the bit-wise
operation selected via bits 7-0 of this register.
Note: Color transparency can be used only when the BitBLT engine is set to a color depth
of 8 or 16 bits per pixel, but not 24 bits per pixel. If the BitBLT engine has been set to a
color depth of 24 bits per pixel, then bit 14 of this register should always remain set to 0 to
disable color transparency.
0 0
0 1
1 0
1 1
Bit
The color value carried by bits 23-0 of either BR01 or BR09 is compared to the color value
resulting from the bit-wise operation being performed for the current pixel. If these two
color values are NOT the same, then the byte(s) for the current pixel at the destination will
be written with the color value resulting from the bit-wise operation.
The color value carried by bits 23-0 of either BR01 or BR09 is compared to the color value
already specified in the byte(s) for the current pixel at the destination. If these two color
values are NOT the same, then the byte(s) for the current pixel at the destination will be
written with the color value resulting from the bit-wise operation.
The color value carried by bits 23-0 of either BR01 or BR09 is compared to the color value
resulting from the bit-wise operation being performed for the current pixel. If these two
color values ARE the same, then the byte(s) for the current pixel at the destination will be
written with the color value resulting from the bit-wise operation.
The color value carried by bits 23-0 of either BR01 or BR09 is compared to the color value
already specified in the byte(s) for the current pixel at the destination. If these two color
values ARE the same, then the byte(s) for the current pixel at the destination will be written
with the color value resulting from the bit-wise operation.
Subject to Change Without Notice
Form of Per-Pixel Color Comparison Selected
BitBLT Registers
Revision 1.3 8/31/98