Graphic Orders
SET_BBMAP
13-42
MC68322 USER’S MANUAL
MOTOROLA
SET_BBMAP
Set Banded Bitmap Parameters
The SET_BBMAP graphic order specifies the structure of a banded bitmap. The current
band number, render direction, and warp are provided in addition to a signed value for
mapping logical addresses to physical addresses and a physical address indicating the end
of the band buffer. These parameters are used in all subsequent graphic orders that only
operate on a banded bitmap. They do not, however, affect transfers to frames or unbanded
bit maps.
The SET_BBMAP graphic order specifies a current band number to be rendered from the
remainder of the display list. The current band number is used in comparison against the
band numbers found in subsequent bitBLT and scanline graphic orders that operate on the
banded bitmap. The result of each band number comparison determines whether a graphic
order is executed during the current pass of the display list. Note that a banded display list
is executed several times. One pass for each band of the page.
The B2T parameter contains a 1-bit flag to indicate render direction. When the
least-significant bit of the B2T byte is set, all subsequent bitBLT and scanline transfers to
banded bit maps are rendered in bottom-to-top order. In other words, bitBLTs begin at the
bottom-most scanline of each frame and proceed towards the top of the frame. Scanline line
tables are read starting with the last bit string specifier and executed in reverse order. When
the B2T flag is set, the MC68322 expects all starting pixel addresses and table addresses
to point to the bottom or end of their respective operands instead of the top. Graphic orders
that operate on frames or unbanded bit maps are unaffected by the B2T flag and are always
rendered in a forward direction. By rendering in a reverse direction, the bands of a 180
° page
can be created in opposite order and transmitted to the print engine to print the back side of
duplex pages. The DWB parameter specifies the destination warp of the banded bitmap.
Note that if the banded bitmap is destined to be printed by the print engine video controller,
the bitmap must adhere to page image requirements. In part, the warp of the bitmap must
equal to 0 mod 16 and the bitmap must not contain any pad words.
PARAMETERS
SIZE
DESCRIPTION
0x08
0x00
BAND
B2T
DWB
PSUBL
EOBPA
Byte
1 of 8 bits
Word
Long Word
SET_BBMAP Opcode.
Reserved.
Current band number.
Bottom to top duplex direction.
Destination banded bitmap warp in bits.
Signed difference between the physical and logical address spaces in bits.
End of band physical bit address.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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