Mode Summary - Motorola HC12 Refrence Manual

Addressing modes determine how the CPU accesses memory locations to be operat-
ed upon. This section discusses the various modes and how they are used.

3.1 Mode Summary

Addressing modes are an implicit part of CPU12 instructions.
STRUCTION REFERENCE
addressing modes are shown in
Table 3-1 M68HC12 Addressing Mode Summary
Addressing Mode
Inherent (no externally supplied
Immediate
Direct
Extended
Relative
Indexed
(5-bit offset)
Indexed
(pre-decrement)
Indexed
(pre-increment)
Indexed
(post-decrement)
Indexed
(post-increment)
Indexed
(accumulator offset)
Indexed
(9-bit offset)
Indexed
(16-bit offset)
Indexed-Indirect
(16-bit offset)
Indexed-Indirect
(D accumulator
offset)
CPU12
REFERENCE MANUAL
SECTION 3
ADDRESSING MODES
shows the modes used by each instruction. All CPU12
Table
Source Format Abbreviation
INST
operands)
INST # opr8i
or
INST # opr16i
INST opr8a
INST opr16a
INST rel8
or
INST rel16
INST oprx5 , xysp
INST oprx3 ,– xys
INST oprx3 ,+ xys
INST oprx3 , xys –
INST oprx3 , xys +
INST abd , xysp
INST oprx9 , xysp
INST oprx16 , xysp
INST [ oprx16 , xysp ]
INST [D, xysp ]
ADDRESSING MODES
3-1.
INH Operands (if any) are in CPU registers
Operand is included in instruction stream
IMM
8- or 16-bit size implied by context
Operand is the lower 8-bits of an address
DIR
in the range $0000 – $00FF
EXT Operand is a 16-bit address
An 8-bit or 16-bit relative offset from the current
REL
pc is supplied in the instruction
IDX 5-bit signed constant offset from x, y, sp, or pc
IDX Auto pre-decrement x, y, or sp by 1 ~ 8
IDX Auto pre-increment x, y, or sp by 1 ~ 8
IDX Auto post-decrement x, y, or sp by 1 ~ 8
IDX Auto post-increment x, y, or sp by 1 ~ 8
Indexed with 8-bit (A or B) or 16-bit (D)
IDX
accumulator offset from x, y, sp, or pc
9-bit signed constant offset from x, y, sp, or pc
IDX1
(lower 8-bits of offset in one extension byte)
16-bit constant offset from x, y, sp, or pc
IDX2
(16-bit offset in two extension bytes)
Pointer to operand is found at...
[IDX2] 16-bit constant offset from x, y, sp, or pc
(16-bit offset in two extension bytes)
Pointer to operand is found at...
[D,IDX]
x, y, sp, or pc plus the value in D
APPENDIX A IN-
Description
MOTOROLA
3-1