4Assembler Directives and Pseudo-Operations

Assembler directives and pseudo-operations allow you to take special programming actions during the assembly process. The directive and pseudo-operation names begin with a period (.) to distinguish them from machine instruction opcodes or extended opcodes.

Introduction

Table 4-1 lists the Assembler directives. Table 4-2 on page 55 lists the pseudo-operations. The directives include those that establish the procedure-calling convention, declare common, and define spaces and subspaces. The pseudo-operations reserve and initialize data areas.

The remainder of this chapter lists the Assembler directives and pseudo-operations in alphabetic order. Several of the descriptions include sample assembly code sequences. You can enter these short code sequences, assemble them using the -loption of the as command, then inspect the offsets and field values to see how that particular directive controls the assembly environment.

This chapter also includes Table 4-3 on page 116 under “Programming Aids” on page 116, which lists the predefined directives that establish standard spaces and subspaces.

Table 4-1

Assembler Directives

 

 

 

 

Directive

Function

 

 

 

 

.ALIGN

Forces location counter to the next largest

 

 

multiple of the supplied alignment value.

 

 

 

 

.ALLOW

Used with a .LEVEL directive, it temporarily

 

 

allows the use of features in the architecture

 

 

specified in the .LEVEL directive.

 

 

 

 

.CALL

Specifies that the next statement is a procedure

 

 

call.

 

 

 

53