Xerox 550 - 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 regi ster R; otherwise, the BP executes the next
instruction in sequence.
AW ADD WORD
0/Vord index alignment)
o 1 2
ADD WORD adds the effective word to the contents of reg-
ister R and loads the sum into register 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
0
Positive
o No fixed-point overflow
Fixed-point overflow
o
No carry from bi t posi tion 0
Carry from bit position 0
If CC2 is set to T 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.
60 Fixed-Point Arithmetic Instructions
AD ADD DOUBlEWORD
(Doub/eword index alignment)
ADD DOUBlEWORD adds the effective doubleword to the
contents of registers Rand Ru1 (treated as a single, 64-bit
register); loads the 32 low-order bits of the sum into reg-
i ster Ru 1 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), (Ru 1), CC Trap: Fixed-pointoverf/ow,
instruction exception
(R, Ru1) + ED - R, Ru1
Condition code settings:
2 3
4
Result in R, Ru1
-
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
(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 fie Id 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
l
ll 11 11 111
X 144444445
1
(Ru 1) X
'
33333333
1
X
'
22222221
'
CC xxxx
0010