MC68HC05JJ6 Datasheet, PDF (177/216 Pages) Freescale Semiconductor, Inc – General Release Specification Microcontrollers

Instruction Set
12.4.2 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.
Table 12-2. Read-Modify-Write Instructions
Instruction
Mnemonic
Arithmetic Shift Left (Same as LSL)
ASL
Arithmetic Shift Right
Bit Clear
Bit Set
ASR
BCLR⁽¹⁾
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
Test for Negative or Zero
ROR
TST⁽²⁾
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 be-
cause it does not write a replacement value.
MC68HC05JJ6/MC68HC05JP6 — Rev. 3.2
Freescale Semiconductor
Instruction Set
General Release Specification
177