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5.6
PIXEL STORE
pst.d fdest, #const (isrc2)
pst.d fdest, #const (isrc2)
+ +
CORE INSTRUCTIONS
Pixel Store
(Normal)
(Autolncrement)
Pixels enabled by PM in mem.d (isrc2
+
#const)
~
fdest
Shift PM right by 8/pixel size (in bytes) bits
IF autoincrement
THEN isrc2
~
#const
+
isrc2
FI
The pixel store instruction selectively updates the pixels in a 64-bit memory location. The
pixel size is determined by the PS field in the
psr.
The pixels to be updated are selected
by the low-order bits of the PM field in the
psr.
Each bit of PM corresponds to one pixel,
with bit 0 corresponding to the pixel at the lowest address.
This instruction is typically used in conjunction with the
fzchks
or
fzchkl
instructions to
implement Z-buffer hidden-surface elimination. When used this way, a pixel is updated
only when it represents a point that is closer to the viewer than the closest point painted
so far at that particular pixel location. Refer to Chapter 6 for more about
fzchks
and
fzchkl.
Traps
If
the operand is misaligned, a data-access trap results.
5-9
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