Reference Guide

53
4 Assembler 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 -l option 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.