Reference Guide

Chapter 4 63

Assembler Directives and Pseudo-Operations

.CALL Directive

The .CALL directive marks the next branch statement as a procedure

call, and permits you to describe the location of arguments and the

function return result.

Syntax

.CALL [ argument_description[ argument_description] ...]

Parameters

argument_

description Allows you to communicate to the linker the types of

registers used to pass ﬂoating point arguments and

receive ﬂoating point return results in the succeeding

procedure call. Similarly, this information can be

communicated in the .EXPORT directive.

The linker requires this information because the

runtime architecture allows ﬂoating point arguments

and return values to reside in either general registers

or ﬂoating point registers, depending on source

language convention. At link time, the linker ensures

that both the caller and called procedure agree on

argument location. If not, the linker may insert code to

relocate the arguments (or return result) before control

is transferred to the called procedure or a procedure

return is completed.

You can use up to 5 argument-descriptions in the

.CALL directive; one for each of the four arguments

that may be passed in registers (arg0–arg3), and one

for a return value (ret0).

NOTE In PA-RISC 2.0W, (64-bit mode) the Assembler ignores the .CALL

directive. This means that the linker does not ensure that the caller and

called procedure agree on argument locations. If you do not know the

prototype of the called procedure, you must pass ﬂoating point