Table of Contents
Advertisement
FLOATING-POINT INSTRUCTIONS
Consider PM as an array of eight bits PM(0) .. PM(7),
where PM(O) is the least-significant bit.
fzchks fsrc1, fsrc2, fdest
(16-Blt Z-Buffer Check)
Consider fsrc1, fsrc2, and fdest as arrays of four 16-bit
fields fsrc1(0) .. fsrc1(3), fsrc2(0) .. fsrc2(3), and fdest(O) .. fdest(3)
where zero denotes the least-significant field.
PM
~
PM shifted right by 4 bits
FOR i
=
0 to
3
DO
PM [i
+
4]
~
fsrc2(i)
=:;
fsrc1 (i) (unsigned)
fdest(i)
~
smaller of fsrc2(i) and fsrc1 (i)
00
MERGE
~
0
pfzchks fsrc1, fsrc2, fdest
(Plpelined 16-Blt Z-Buffer Check)
Consider fsrc1, fsrc2, and fdest as arrays of four 16-bit
fields fsrc1 (0) .. fsrc1(3) , fsrc2 (0) .. fsrc2(3) , and fdest(0) .. fdest(3)
where zero denotes the least-significant field.
PM
~
PM shifted right by 4 bits
FOR i
=
0 to
3
DO
PM [i
+
4]
~
fsrc2(i)
=:;
fsrc1 (i) (unsigned)
fdest
~
last stage graphics result
last stage graphics result (i)
~
smaller of fsrc2(i) and fsrc1 (i)
00
MERGE
~
0
fzchkl fsrc1, fsrc2, fdest
(32-Blt Z-Buffer Check)
Consider fsrc1, fsrc2, and fdest as arrays of two 32-bit
fields fsrc1(0) .. fsrc1(1). fsrc2(0) .. fsrc2(1), and fdest(0) .. fdest(1)
where zero denotes the least-significant field.
PM
~
PM shifted right by 2 bits
FOR i
=
0 to
1
DO
PM [i
+
6]
~
fsrc2(i)
=:;
fsrc1 (i) (unsigned)
fdest(i)
~
smaller of fsrc2(i) and fsrc1 (i)
00
MERGE
~
0
pfzchkl fsrc1, tsrc2, tdest
(Pipeiined 32-Bit Z-Buffer Check)
Consider fsrc1, fsrc2, and fdest as arrays of two 32-bit
fields fsrc1(0) .. fsrc1(1), fsrc2(0) .. fsrc2(1), and fdest(0) .. fdest(1)
where zero denotes the least-significant field.
PM
~
PM shifted right by 2 bits
FOR i
=
0 to 1
DO
PM [i
+
6]
~
fsrc2(i)
=:;
fsrc1 (i) (unsigned)
fdest(i)
~
last stage graphics result
last stage graphics result
~
smaller of fsrc2(i) and fsrc1 (i)
00
MERGE
~
0
The instructions
fzchks
and
fzchkl
perform mUltiple unsigned-integer (ordinal) compar-
isons. The inputs to the instructions
fzchks
and
fzchkl
are normally taken from two
arrays of values, each of which typically represents the distance of a point from the
6-30
Advertisement
Table of Contents
