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Instruction Set
Instruction Types
MC68HC05RC16 — Rev. 3.0 General Release Specification
MOTOROLA Instruction Set 91
10.4.2 Read-Modify-Write Instructions
These instructions read a memory location or a register, modify its
contents, and write the modified value back to the memory location or to
the register.
NOTE: Do not use read-modify-write operations on write-only registers.
1. Unlike other read-modify-write instructions, BCLR and
BSET use only direct addressing.
2. TST is an exception to the read-modify-write sequence
because it does not write a replacement value.
Table 10-2. Read-Modify-Write Instructions
Instruction Mnemonic
Arithmetic Shift Left (Same as LSL) ASL
Arithmetic Shift Right ASR
Bit Clear BCLR
(1)
Bit Set BSET
(1)
Clear Register CLR
Complement (One’s Complement) COM
Decrement DEC
Increment INC
Logical Shift Left (Same as ASL) LSL
Logical Shift Right LSR
Negate (Two’s Complement) NEG
Rotate Left through Carry Bit ROL
Rotate Right through Carry Bit ROR
Test for Negative or Zero TST
(2)