Xerox 560 - Page 67

Condition code settings:
2
3 4 Result in R
-
0 0 Zero
-
0
Negative
0 Positive
- 0 - No fixed-point overflow
- -
Fixed-point overflow
o - No carry from bit position 0
- - - Carry from bit position 0
If CC2 is set to 1 and the fixed-point arithmetic trap mask
is 1,
the BP traps to location X
'
43
1
after loading the
sum into register R; otherwise, the BP executes the next
instruction in sequence.
AW ADD WORD
0Nord
index alignment)
30
o 1 2
ADD WORD adds the effective word to the contents of reg-
ister R and loads the sum into reqister R.
Affected: (R), CC
Trap: Fixed-point overflow
(R) + EW-R
Condition code settings:
2 3 4 Result in R
- -
0 0 Zero
-
0 Negative
o Positive
- 0 - - No fixed-point overflow
-
Fixed-point overflow
o
No carry from bit position 0
Carry from bit position 0
If CC2 is set to 1 and the fixed-point arithmetic trap mask
(AM) is a 1, the BP traps to location X
'
43
1
after loading
the sum into register R; otherwise, the BP executes the
next instruction in sequence.
AD ADD DOUBLEWORD
(Doubleword index alignment)
ADD DOUBLEWORD adds the effective doubleword to the
contents of registers Rand Ru 1 (treated as a single, 64-bit
register); loads the 32 low-order bits of the sum into reg-
ister Rul and then loads the 32 high-order bits of the sum
into register R. R must be an even value; if R is an
odd value, the BP traps with the contents in register R
unchanged.
Affected: (R), (Rul), CC
(R, Ru 1) + ED - R, Ru 1
Condi tion
code settings:
2 3 4 Result in
R, Ru1
- 0 0 Zero
o Negative
o Positive
Trap: Fixed-point overflow,
instruction exception
- 0 -
No fixed-point overflow
-
Fixed-point overflow
o - - - No carry from bit position 0
- - - Carry from bit position 0
If CC2 is set to 1 and the fixed-point arithmetic trap mask
(AM) is a 1,
the BP traps to location X
'
43
1
after loading
the sum into registers Rand Ru1; otherwise, the BP exe-
cutes the next instruction in sequence.
The R field of the AD instruction must be an even value for
proper
operation of the instruction; if the R field of AD is
an odd value, the instruction traps to location X
'
4D
'
,
instruction exception trap.
Example 1, even R field value:
Before execution
After execution
ED
X
'
33333333EEEEEEEE
'
X
'
33333333EEEEEEEE
'
(R)
X
'
11111111
1
X
'
44444445
1
(Ru 1)
X 133333333 I
X 1222222211
CC
xxxx
0010
Fixed-Point Arithmetic Instructions 61