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OTHER SYSTEM FUNCTIONS
27.1 -- Register Functions
27.
1.
11
Sub trac
t
X
from
B, A - - . SUXBA
The
.SUXBA
function
subtracts
the
contents of the
X
register from the contents of the register pair
B,A.
ENTRY PARAMETERS:
EXIT
CONDITIONS:
None.
A
has been decremented by
XL.
B
has been decremented by
XH
and
C.
X
is unchanged.
CC has been set as in
a
normal
unsigned
subtraction.
27. 1. 12
Compare
B. A wi th X -- . CPBAX
The
. CPBAX
function
compares
the
contents
of
the
~egister
pair
B,A
to the contents
or
the
X
register.
ENTRY PARAMETERS:
None.
EXIT
CONDITIONS:
A
is unchanged.
B
is unc hang ed.
X
is unchanged.
CC has been set
as
in a
normal
unsigned
sub trac
t
ion.
27.1. 13 Shirt
x
right -- . ASRX
The. ASRX function shifts the contents of the
X
register
to the right
by
one bit position.
Bit
15
is
held
constant
and bit 0 is moved into C.
ENTRY PARAMETERS:
EXIT CONDITIONS:
None.
A
is unchanged.
B
is unchanged.
X
is shifted right one bit position.
The
sign bit
is
propagated into the lower
bits upon subsequent shifts.
C contains bit zero of the entry value of
X.
The
remainder
of
CC
is
indeterminate.
27. 1. 14 8h
i
ft X left -- . ASLX
The. ASLX function shifts the contents of the X register
to the" left
by
one bit position.
Bit 0 is filled with zero.
ENTRY PARAMETERS:
None.
Page
27-05
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