INSTRUCTION DESCRIPTIONS
MOTOROLA
INSTRUCTION SET DETAILS A - 175
Note
:Due to instruction pipelining, if an AGU register (Mn, Nn, or Rn) is directly changed
with this instruction, the new contents may not be available for use until the second fol-
lowing instruction. See the restrictions discussed in A.9.6 - R, N, and M Register Restric-
tions on page A-page 310.
Example:
:
ASL A R2,X:–(R2) ;A
∗
2
➞
A, save updated R2 in X:(R2)
:
Explanation of Example:
Prior to execution, the 16-bit R2 address register contains the
value $1001, and the 24-bit X memory location X:$1000 contains the value $000000.
The execution of the parallel move portion of the instruction, R2,X:–(R2), predecrements
the R2 address register and then uses the R2 address register to move the updated con-
tents of the R2 address register into the 24-bit X memory location X:$1000.
Condition Codes:
S — Computed according to the definition in A.5 CONDITION CODE COMPUTATION.
L — Set if data limiting has occurred during parallel move.
Note:
The MOVE A,X:ea operation will result in a 24-bit positive or negative saturation
constant being stored in the specified 24-bit X memory location if the signed integer por-
tion of the A accumulator is in use.
X:$1000 X:$1000
$000000 $001000
Before Execution After Execution
R2 R2
$1001 $1000
X: X Memory Data Move X:
MR CCR
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
LF DM T ** S1 S0 I1 I0 SLEU N Z V C