Xerox 560 Reference Manual page 59

Example 2, odd R field value:
Before execution After execution
ED X'0123456789ABCDEP X'0123456789ABCDEF'
(R)
xxxxxxxx X'FEDCBA98'
CC xxxx x001
LAD
LOAD ABSOLUTE DOUBLEWORD
(Doubleword index alignment)
If the effective doubleword is positive, LOAD ABSOLUTE
DOUBLEWORD loads the 32 low-order bits of the effective
doubleword into register Ru1, and then loads the 32 high-
order bits of the effective doubleword into register R. If R is
an odd value, the result in register R is the 32 high-order
bits of the effective doubleword. The condition code set-
tings are based on the effective doubleword, rather than
the final result in register R.
If the effective doubleword is negative, LAD forms the
64-bit two's complement of the effective doubleword, loads
the 32 low-order bits of the two's complemented double-
word into register Ru 1, and then loads the 32 high-order
bits of the two's complemented doubleword into register R.
If R is an odd value, the result in register R is the 32 high-
order bits of the two's complemented doubleword. The con-
dition code settings are based on the two's complement of
.LL _ _ CC_ ... - _I I I I . 1 . 1 . 1 , . . . I I • •
11'1::
I::1II::~IIVl::
UUUUII::VVUIU, IUHH:::r IrIun rne nnol resulT In
register R.
Fixed-point overflow occurs if the effective doubleword is
-2 63 (X'8000000000000000'), in which case the result in
registers Rand Rul is -2 63 and CC2 is set to 1; otherwise,
CC2 is reset to O.
Affected: (R), (Ru 1),CC2,
CC3,CC4
Trap: Fixed-point overflow
IED1
32
_
63
-Ru1i IEDI
0
_
31
- R
Condition code settings:
2 3 4 Absolute value of effective doubleword
- 0 0 0 Zero
o
Nonzero
- 0 No fixed-point overflow
o
Fixed-point overflow (sign bit on)
If CC2 is set to 1 and the fixed-point arithmeti c trap mask
(AM) is a 1, the BP traps to location X'43' after execution
of LOAD ABSOLUTE DOUBLEWORDi otherwise, the BP
executes the next instruction in sequence.
Example 1, even R field value:
Before execution After execution
ED
X'0123456789ABCDEF'
X'0123456789ABCDEF'
(R) xxxxxxxx X'01234567'
(Ru1)
=
xxxxxxxx X'89ABCDEF'
CC
xxxx
xOlO
Example 2, even R field value:
Before execution After execution
ED X' FEDCBA9876543210' X' FEDCBA987654321 0'
(R) xxxxxxxx X'01234567'
(Rul) = xxxxxxxx X'89ABCDFO'
CC xxxx xOlO
Example 3, odd R field value:
Before execution After execution
ED - X'G.23456789ADCDEF X'G.23456789ADCDEF
(R)
xxxxxxxx X'01234567'
CC xxxx xOlO
LAS
LOAD AND SET
(Word index alignment)
LOAD AND SET loads the effective word into R. If
the effective address is equal to or greater than 16, a
one is stored in the sign position of the effective loca-
tion.
If
the effective address is equal to or less than 15
(effective location is a general register), the sign bit
remains unchanged. This instruction is used to interlock
multiple processors from the simultaneous execution of
certai n secti ons of code or from the si mu
I
taneous access
to certain tables.
Affected: (R), CC3, CC4
EW-R
1 -EW O ' if EA
~
16
Load/Store Instructions 53