as for the ESA/390 supports all of the standard ELF/SVR4
assembler directives that are documented in the main part of this
documentation. Several additional directives are supported in order
to implement the ESA/390 addressing model. The most important of these
These are the additional directives in
as for the ESA/390:
.usingdirective in the same section as the current section.
.stringetc. emit ascii strings by default.
asdirective .equ can be used to the same effect.
.usingmust have been previously specified in the same section.
This assembler allows two
.using directives to be simultaneously
outstanding, one in the
.text section, and one in another section
.data section). This feature allows
dynamically loaded objects to be implemented in a relatively
straightforward way. A
.using directive must always be specified
.text section; this will specify the base register that
will be used for branches in the
.text section. A second
.using may be specified in another section; this will specify
the base register that is used for non-label address literals.
When a second
.using is specified, then the subsequent
.ltorg must be put in the same section; otherwise an error will
Thus, for example, the following code uses
r3 to address branch
r4 to address the literal pool, which has been written
.data section. The is, the constants
=E'3.1416' will all appear in the
.data .using LITPOOL,r4 .text BASR r3,0 .using *,r3 B START .long LITPOOL START: L r4,4(,r3) L r15,=A(some_routine) LTR r15,r15 BNE LABEL AH r0,=H'42' LABEL: ME r6,=E'3.1416' .data LITPOOL: .ltorg
Note that this dual-
.using directive semantics extends
and is not compatible with HLASM semantics. Note that this assembler
directive does not support the full range of HLASM semantics.