Both
byte
strings
are
C bytes in length. When the instruction
is
completed,
the
destination
and source addresses
are
each
incremented
by C, and C is
set
to
zero.
Case II, odd R
fi
e
Id
(Ru
1
=R)
Contents
of
register
R:
The source
byte
string begins with
the
byte
location
pointed
to by the address in register R plus the
displacement
in
MBS;
the
destination
byte string begins with
the
byte
location
pointed
to by the
destination
address in
register
R.
Both
byte
strings
are
C bytes in length. When the instruction
is
completed,
the
destination
address is
incremented
by C,
and C
is
set
to
zero.
Case III,
zero
R
field
(Rul=l)
Contents
of
register 1:
The source
byte
string consists
of
a
single
byte,
the
con-
tents
of
the
byte
location
pointed
to by the
displacement
in
MBS;
the
destination
byte
string begins
with
the
byte
loca-
tion
pointed
to by the
destination
address in
register
1 and
is
C bytes in length.
In
this
case,
the
source
byte
is
dupli-
cated
throughout
the
destination
byte
string. When
the
instruction is
completed,
the
destination
address is
incre-
mented by
C,
and C is
set
to
zero.
CBS
COMPARE
BYTE
STRING
{Immediate
displacement,
continue
after
interrupt}
COMPARE
BYTE
STRING compares, as magnitudes,
the
contents
of
the
source
byte
string
with
the
contents
of
the
destination
byte
string, byte by corresponding
byte,
beginning with the first
byte
of
each
string. The
com-
parison
continues
unti I the
specified
number
of
bytes
have
been compared
or
unti I an
inequality
is found. When
CBS
is
terminated,
CC3
and
CC4
are
set
to
indicate
the
resultof
the
last comparison. If the
CBS
instruction terminates
due
to
inequality,
the
count
in
register
Rul
is
one
greater
than
the
number
of
bytes remaining to be compared; the source
ad-
dress in register R and
the
destination
address in
register
Rul
indicate
the
locations
of
the unequal bytes.
Affected:
{R},
(Rul), CC3,
CC4
(SBS)
:
(DBS)
Condition
code
settings:
2 3 4 Result
of
CBS
- 0 0 Source
byte
string
equals
destination
byte
string
or
initial
byte
count
is equal to
zero.
- 0 Source byte string less than
destination
byte
string.
o Source
byte
string
greater
than
destination
byte
string.
If
CBS
is
indirectly
addressed,
it
is
treated
as a
nonexistent
instruction.
The
basic
processor
unconditionally
aborts
execution
of
the
instruction (at the time
of
operation
code
decoding)
and traps to
location
X'40'
with
the
contents
of
register
R and the
destination
byte
string
unchanged.
See
"Traps
By
Byte String Instructions" (in this
section)
for
other
trap
conditions.
Case I,
even,
nonzero R
field
{Rul=R+l}
Contents
of
register
R:
Contents
of
register
R+l:
Ihe source
byte
string begins
with
the
byte
iocatlon
pointed
to by the source address in
register
R plus
the
displacement
in
CBS;
the
destination
byte
string begins with the
byte
lo-
cation
pointed
to by the
destination
address in
register
R+l.
Both byte strings
are
C bytes in length.
Case II, odd R
field
(Ru
l=R)
Contents
of
register
R:
The source
byte
string begins
with
the
byte
location
pointed
to by
the
address in register R plus
the
displacement
in CBS;
the
destination
byte
string begins
with
the
byte
location
pointed
to by the
destination
address in register
R.
Both
byte
strings
are
C bytes in length.
Case III,
zero
R field
(Rul=l)
Contents
of
register 1:
The source
byte
string consists
of
a single
byte,
the
con-
tents
of
the
location
pointed
to by
the
displacement
in CBS;
Byte-String Instructions
89
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