2.
two hexadecimal digits
by specifying a zero in the
both operands.
3. To remove the zone bits of all
bytes of a field, including the
rightmost byte, both operands must
be extended on the right with a
dummy
ignored
4. The storage-operand references for
ences.
o 8 12 15
The first operand
condition code and the program mask of
the current
ignored.
of the instruction are
Bits 2 and 3 of general register
replace the program mask. Bits
and 8-31 of general register
ignored.
Condition Code:
specified by bits
register
2 and 3 of
set as
general
1. Bits 2-7 of the general register
may have been loaded from the
2.
the condition code and the mask
bits in either the problem state or
the supervisor state.
3. The program should take into
consideration that the setting of
the program mask can have a signif-
icant effect on subsequent
execution of the program. Hot only
do the four mask bits control
whether the corresponding inter
ruptions occur, but the exponent
underflow and significance masks
also determine the result which is
obtained.
SHIFT LEFT DOUBLE
o 8 12 16
The 63-bit numeric part of the signed
first operand is shifted left the number
of bits specified by the second-operand
address, and the result is placed at the
first-operand location.
Bits 12-15
ignored.
of the instruction are
The
of general registers and must designate
specification exception is recognized.
The second-operand address
to address data; its rightmost six bits
indicate the number of bit positions to
be shifted. The remainder of the
address
The first operand is treated
signed binary integer. The sign posi
tion of the even-numbered register
remains unchanged. The leftmost bit
position of the odd-numbered register
contains a numeric
ipates in the shift in the same manner
the right.
If one or more bits unlike the sign bit
are shifted out of bit position 1 of the
even-numbered register, an overflow
occurs, and condition code 3 is set. If
the fixed-point-overflow mask bit is
one,
point overflow occurs.
Resulting Condition Code:
o
1
2
3
Result zero; no overflow
Result less than zero; no over
flow
Result greater than zero; no
overflow
Overflow
Fixed-point overflow
Specification
Chapter 7. General Instructions 7-31