INSTRUCTION DESCRIPTIONS
A - 290 INSTRUCTION SET DETAILS MOTOROLA
Operation: Assembler Syntax:
S–0 (parallel move) TST S (parallel move)
Description: Compare the specified source accumulator S with zero and set the condi-
tion codes accordingly. No result is stored although the condition codes are updated.
Example: :
TST A #$345678,B ;set CCR bits for value in A, update B
:
Explanation of Example: Prior to execution, the 56-bit A accumulator contains the
value $01:020304:000000, and the 16-bit condition code register contains the value
$0300. The execution of the TST A instruction compares the value in the A register with
zero and updates the condition code register accordingly. The contents of the A accumu-
lator are not affected.
Condition Codes:
S — Computed according to the definition in A.5 CONDITION CODE COMPUTATION
L — Set if data limiting has occurred during parallel move
E — Set if the signed integer portion of A or B result is in use
U — Set if A or B result is unnormalized
N — Set if bit 55 of A or B result is set
Z — Set if A or B result equals zero
V — Always cleared
Note: The definitions of the E and U bits vary according to the scaling mode being used.
Refer to Section A.5 CONDITION CODE COMPUTATION for complete details.
TST Test Accumulator TST
Before Execution After Execution
A$01:020304:000000
CCR CCR
$0300 $0330
$01:020304:000000
A
MR CCR
1514131211109876543210
LF DM T ** S1 S0 I1 I0 SLEUNZVC