Chapter 26. M680x0 Dependent Features

155

26.3. Motorola Syntax

The standard Motorola syntax for this chip differs from the syntax already discussed (Section 26.2

Syntax).

as

can accept Motorola syntax for operands, even if mit syntax is used for other operands in

the same instruction. The two kinds of syntax are fully compatible.

In the following table

apc

stands for any of the address registers (

%a0

through

%a7

), the program

counter (

%pc

), the zero address relative to the program counter (

%zpc

), or a suppressed address reg 

ister (

%za0

through

%za7

). The use of

size

means one of

w

or

l

, and it may always be omitted along

with the leading dot. The use of

scale

means one of

1

,

2

,

4

, or

8

, and it may always be omitted along

with the leading asterisk.

The following additional addressing modes are understood:

Address Register Indirect

(%a0)

through

(%a7) %a7

is also known as

%sp

, i.e. the Stack Pointer.

%a6

is also known as

%fp

, the Frame Pointer.

Address Register Postincrement

(%a0)+

through

(%a7)+

Address Register Predecrement

 (%a0)

through

 (%a7)

Indirect Plus Offset

number(%a0)

through

number(%a7)

, or

number(%pc)

.

The

number

may also appear within the parentheses, as in

(number,%a0)

. When used with the

pc

, the

number

may be omitted (with an address register, omitting the

number

produces Address

Register Indirect mode).

Index

number(apc,register.size*scale)

The

number

may be omitted, or it may appear within the parentheses. The

apc

may be omitted.

The

register

and the

apc

may appear in either order. If both

apc

and

register

are address

registers, and the

size

and

scale

are omitted, then the first register is taken as the base register,

and the second as the index register.

Postindex

([number,apc],register.size*scale,onumber)

The

onumber

, or the

register

, or both, may be omitted. Either the

number

or the

apc

may be

omitted, but not both.

Preindex

([number,apc,register.size*scale],onumber)

The

number

, or the

apc

, or the

register

, or any two of them, may be omitted. The

onumber

may be omitted. The

register

and the

apc

may appear in either order. If both

apc

and

register

are address registers, and the

size

and

scale

are omitted, then the first register

is taken as the base register, and the second as the index register.