
Graphic Operations
MOTOROLA
MC68322 USER’S MANUAL
12-7
Figure 12-3. Bit String Specifier Formats
The ID field identifies the type of bit string specifier. The bit string specifiers are designed to
be recognizable no matter what direction the scanline table is read from memory. This is
required to properly handle scanline graphic orders in a duplex banding environment where
0
° and 180° pages are possible. Thus, the ID fields in the 32- and 48-bit bit string specifiers
are duplicated to allow parsing of the scanline table in either direction. The RL field indicates
the number of pixels to be drawn horizontally during the scanline run.
The displacement fields indicate the number of horizontal and vertical pixels to skip before
drawing a scanline. The DX field indicates the signed horizontal movement along the X
dimension of the bitmap. The DY field indicates the unsigned vertical movement along the
Y dimension of the bitmap. The DZ field is the signed aggregate displacement based on a
calculation of the preferred X and Y movements along with the destination warp. Thus, the
warp of the target bitmap must be known before building a scanline table containing 48-bit
bit string specifiers. This calculation is DZ = (DY x DW) + DX, where DW is the unsigned
warp of the target destination bitmap. Note that DY is signed for this calculation. Table 12-2
lists the definitions for each field of the three types of bit string specifiers.
16-BIT SPECIFIER
32-BIT SPECIFIER
48-BIT SPECIFIER
ID=0
ID = 102
ID = 112
+0
+2
+0
BYTE ADDRESS
OF WORD
+2
+4
DY
RL
DX
MSB
LSB
15
14
13
12
11
10
9
8
7
65432
1
0
15
14
13
12
11
10
9
8
7
65432
1
0
15
14
13
12
11
10
9
8
7
65432
1
0
NOTES:
RL = Run Length (unsigned)
DX = X Dimension Displacement—Horizontal (signed)
DY = Y Dimension Displacement—Vertical (unsigned)
DZ = X and Y Dimension Displacement—Horizontal and Vertical (signed)
DZ
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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