Graphics Status Register (Gsr) - Sun Microsystems UltraSPARC-I User Manual

13.3.2 Fixed Data Formats
The fixed 16-bit data format consists of four 16-bit signed fixed-point values con-
tained in a 64-bit word. The fixed 32-bit format consists of two 32-bit signed fixed
point-values contained in a 64-bit word. Fixed data values provide an intermedi-
ate format with enough precision and dynamic range for filtering and simple im-
age computations on pixel values. Conversion from pixel data to fixed data
occurs through pixel multiplication. Conversion from fixed data to pixel data is
done with the pack instructions, which clip and truncate to an 8-bit unsigned val-
ue. Conversion from 32-bit fixed to 16-bit fixed is also supported with the
FPACKFIX instruction. Rounding can be performed by adding 1 to the round bit
position. Complex calculations needing more dynamic range or precision should
be performed using floating-point data.
Figure 13-1 shows the graphics data formats.
Pixel
Fixed16
Fixed32
Figure 13-1
Note: Sun frame buffer pixel component ordering is: α, B, G, R.

13.4 Graphics Status Register (GSR)

The GSR is accessed with implementation-dependent RDASR and WRASR in-
structions using ASR 13
opcode
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
RDASR
31 24 23
int frac int
63 48 47
int
63
Graphics Data Formats
.
16
op3 reg field
10 1000
rs1 = 19
13. UltraSPARC Extended Instructions
16 15
frac int frac
32 31
frac int
32 31
operation
Read GSR
8 7 0
int frac
16 15 0
frac
0