Lch; Lah - Xerox 550 Reference Manual

Condition code settings:
2 3 4 Result in R
0
0
Zero
0
Negative
0
Positive
LD
LOAD DOUBLEWORD
(Doubleword index alignment)
LOAD 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
settings are based on the effective doubleword, rather than
the final result in register R (see example 3, below).
Affected: (R), (Rul), CC3, CC4
ED32-63Ru1; ED
O _
3 1 R
Condition code settings:
2 3 4 Effecti ve doubl eword
o
0 Zero
o
Negative
o
Positive
Example 1, even R field value:
Before execution After execution
ED X'0123456789ABCDEF' X'0123456789ABCDEF'
(R) xxxxxxxx X'01234567'
(Rul)
=
xxxxxxxx X'89ABCDEF'
CC xxxx
xx10
Example 2, odd R field value:
Before execution After execution
ED X'0123456789ABCDEF' X'0123456789ABCDEF'
(R)
xxxxxxxx X'01234567'
CC xxxx xx10
50 Load/Store Instructions
Example 3, odd R field value:
Before execution After execution
ED X'0000000012345678'
X'0000000012345678'
(R) xxxxxxxx X' 00000000'
CC xxxx
xx10
LCH
LOAD COMPLEMENT HALFWORD
(Halfword index alignment)
LOAD COMPLEMENT HALFWORD extends the sign of the
effective halfword 16 bit positions to the left and then loads
the 32-bit two's complement of the result into register R.
(Overflow cannot occur. )
Affected: (R), CC3, CC4
_[EHSE]-R
Condition code settings:
2 3 4 Resu
I
tin R
LAH
o
0 Zero
o
Negative
o
Positive
LOAD ABSOLUTE HALFWORD
(Halfword index alignment)
If the effective halfword is positive, LOAD ABSOLUTE
HALFWORD extends the sign of the effective halfword
16 bit positions to the left and then loads the 32-bit result
in register R. If the effective halfword is negative, LAH
extends the sign of the effective halfword 16 bit positions
to the left and then loads the 32-bit two's complement of
the result into register R. (Overflow cannot occur.)
Affected: (R), CC3, CC4
EHSE - R
Condition code settings;
2 3 4 Result in R
o
0 Zero
o
Nonzero