Motorola HC12 - Manual (Page 143)

Assembler Syntax
Source Line
MCUez HC12 Assembler User’s Manual
MOTOROLA Assembler Syntax 143
7.4.3.15 Indexed-Indirect, D Accumulator Offset
This addressing mode adds the value in D to the base index register. This forms
the memory address containing a pointer to the memory location referenced in
the instruction. The base index register may be X, Y, SP, or PC.
Example:
entry1: NOP
NOP
entry2: NOP
NOP
entry3: NOP
NOP
main:
LDD #2
JMP [D, PC]
goto1: DC.W entry1
goto2: DC.W entry2
goto3: DC.W entry3
This example represents a jump table. The values beginning at goto1 are
potential destinations for the jump instruction.
When JMP [D, PC] is executed, PC points to goto1 and D holds the
value 2.
The JMP instruction adds the value in D and PC to form the address of goto2 .
The CPU reads the address stored there (the address of label entry2) and jumps
to that location.