Compaq ECQD2KCTE manual Instruction Operand Notation, Operand Name Notation

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3.2.2 Instruction Operand Notation

The notation used to describe instruction operands follows from the operand specifier notation used in the VAX Architecture Standard. Instruction operands are described as follows:

<name>.<access type><data type>

3.2.2.1 Operand Name Notation

Specifies the instruction field (Ra, Rb, Rc, or disp) and register type of the operand (integer or floating). It can be one of the following:

Table 3–4: Operand Name Notation

Name

Meaning

 

 

disp

The displacement field of the instruction

fnc

The PALcode function field of the instruction

Ra

An integer register operand in the Ra field of the instruction

Rb

An integer register operand in the Rb field of the instruction

#b

An integer literal operand in the Rb field of the instruction

Rc

An integer register operand in the Rc field of the instruction

Fa

A floating-point register operand in the Ra field of the instruction

Fb

A floating-point register operand in the Rb field of the instruction

Fc

A floating-point register operand in the Rc field of the instruction

 

 

3.2.2.2 Operand Access Type Notation

A letter that denotes the operand access type:

Table 3–5: Operand Access Type Notation

Access Type

Meaning

 

 

a

The operand is used in an address calculation to form an effective

 

address. The data type code that follows indicates the units of addressabil-

 

ity (or scale factor) applied to this operand when the instruction is

 

decoded.

 

For example:

 

".al" means scale by 4 (longwords) to get byte units (used in branch dis-

 

placements); ".ab" means the operand is already in byte units (used in

 

load/store instructions).

i

The operand is an immediate literal in the instruction.

 

 

Instruction Formats 3–5

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Compaq ECQD2KCTE manual Instruction Operand Notation, Operand Name Notation Meaning, Operand Access Type Notation