Reference Guide

Chapter 1 17
Introduction to PA-RISC Assembly Language
Summary of Changes for PA-RISC 2.0
Summary of Changes for PA-RISC 2.0
The following features have changed in PA-RISC 2.0 architecture. These
changes are explained in more detail in the appropriate locations in this
manual.
• A new .DWORD directive reserves 64 bits (a double word) of storage
and initializes it to the given value.
• A .LEVEL 2.0 directive should be used as the first directive in the
source file to assemble it for a PA-RISC 2.0 system.
• New +DA2.0 option
• New and changed Assembler error messages
Summary of Changes for PA-RISC 2.0W
(Wide Mode, 64-bit)
The Assembler for PA-RISC 2.0W, the 64-bit version of PA-RISC 2.0,
maintains the same source syntax as that of PA1.x and PA2.0 32-bit
mode versions. However, PA2.0W features differ in the features listed
below.
• To assemble a source file for a PA-RISC 64-bit system, use a .LEVEL
2.0W directive as the first directive in the source file. See “.LEVEL
Directive” on page 93.
• The Assembler generates an Executable and Linking Format (ELF)
object file format with PA-RISC 2.0W. Refer to the ELF 64 Object File
Format, URL: http://www.software.hp.com/STK/ for details on ELF
format.
• PA-RISC 2.0W supports a flat virtual address space of 2**64 bytes,
and therefore does not support use of space registers. Use the
following syntax when memory operations are used:
ex: LDD disp(b), tgt