Graphic Orders
BLT2BB_XHD
13-20
MC68322 USER’S MANUAL
MOTOROLA
The SA parameter defines the unexpanded source bitmap bit address. It must point to the
upper left corner of the bitmap when the B2T flag is clear and to the lower left corner of the
bitmap when the B2T flag is set. The warp of the unexpanded bitmap is set by the SW
parameter. This value is added to SA to locate the beginning of each successive scanline.
Notice that the source warp set by the SET_SBMAP graphic order has no effect on this
graphic order.
The XOFF:XMUL operand is divided into two fields. The least-significant four bits contain
the XMUL field, which specifies the factor used to scale the unexpanded source bitmap in
the X dimension. XMUL must equal a specific value from 0–15, which represents a scaling
factor of 1–16. Only certain scaling factors are supported, as defined in Table 13-3. Values
other that those listed are ignored and no X scaling is performed. The XOFF field occupies
the four most-significant bits and indicates the number of bits to be clipped at the left edge
of the expanded source bitmap. XOFF ranges from 0–XMUL. If XOFF is zero, no clipping
occurs at the left extent, but if it is non-zero, XOFF number of bits in the left edge of the
expanded bitmap are skipped and the next bit is the first bit transferred to the destination
bitmap. The YOFF:YMUL operand is also divided into two fields. The least-significant four
bits contain the YMUL field, which specifies the factor used to scale the unexpanded source
bitmap in the Y dimension. YMUL can equal any value from 0–15, which represents a
scaling factor of 1–16.
The YOFF field occupies the four most-significant bits in the YOFF:YMUL operand. YOFF
indicates the number of scanlines to be clipped at the top or bottom edge of the expanded
source bitmap, depending on the value of the B2T flag. When B2T is clear, YOFF is defined
from the top edge of the source bitmap. When B2T is set, YOFF is defined from the bottom
edge. YOFF ranges from 0–YMUL. If YOFF is zero, no clipping occurs at the top or bottom
extent, but if it is non-zero, YOFF number of scanlines at the top or bottom edge of the
expanded bitmap are skipped and the next scanline is the first one transferred to the
destination bitmap.
Halftone tiled patterns are typically anchored to the page. Thus, a bitBLT may need to take
on the halftone pattern starting at various points in the halftone bitmap depending on where
it is positioned on the page. The halftone parameters HXR, HYR, and HA define the precise
halftone pixel that corresponds to the upper left (or lower left, when the B2T flag is set)
corners of the source and destination frames. HXR specifies the number of pixels remaining
to the right edge of the bitmap and HYR defines the number of scanlines remaining to the
bottom edge (or top edge, when the B2T flag is set).
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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