HCS12 Assembly Programming - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 74

Example 2.18
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What are the values of accumulator A and the C flag after executing the asla instruction
assuming that originally A contains $95 and the C flag is 1?
Solution: The operation of this instruction is shown in Figure 2.11a.

C flag Accumulator A

1 00 1 0 1 0 1 0

00 1 0 1 0 1 0

1

Figure 2.11a ■ Operation of the asla instruction

The result is shown in Figure 2.11b.

Original Value New Value

[A] = 10010101
C = 1

[A] = 00101010
C = 1

Figure 2.11b ■ Execution result of the asla instruction

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Example 2.19
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What are the new values of the memory location at $1000 and the C flag after executing the
instruction asr $1000 ? Assume that the memory location $1000 originally contains the value of
$ED and the C flag is 0.
Solution: The operation of this instruction is shown in Figure 2.12a.

1 11 0 1 1 0 1

C flag

Memory location
$1000

11 1 1 0 1 1 0 1

Figure 2.12a ■ Operation of the asr $1000 instruction