Open System Services Porting Guide (G06.24+, H06.03+)

Table Of Contents
Porting From Specific UNIX Systems
Open System Services Porting Guide520573-006
9-8
GNU C Compiler
Because applications that use strictly ISO/ANSI C semantics are the easiest to
port, your application should compile successfully with the -Xa flag before being
considered ready to port to the OSS environment.
GNU C Compiler
The GNU C compiler supports ISO/ANSI C language syntax and supports a “pedantic”
mode, which requires strict adherence ISO/ANSI C. It supports the following:
ISO/ANSI C and Common C.
Relevant compiler flags:
Because applications that use strictly ISO/ANSI C semantics are the easiest to
port, your application should compile successfully with the -pedantic flag before
being considered ready to port to the OSS environment.
Optional additional GNU utilities:
These additional utilities are not provided in the OSS environment. The proper
functioning of your application should not depend upon these tools after it is ported
to the OSS environment.
Resolving the Endian Problem
The term “endian” refers to the order in which a computer numbers and stores its
bytes. There are two kinds of byte-endian ordering:
Big endian, in which the most significant byte of a multiple-byte entity (of a word,
for example) is stored first (at the lowest memory byte address or word boundary,
represented as the leftmost byte)
Little endian, in which the least significant byte is stored first (represented as the
rightmost byte)
Systems such as NonStop servers, IBM 360 and later mainframes, the IBM RS 6000,
and Sun Solaris use big-endian byte ordering. Systems based on the Intel x86 platform
(such as Microsoft Windows systems), HP OpenVMS systems, and HP Tru64 UNIX®
on the Alpha architecture use little-endian byte ordering.
-ansi Supports ISO/ANSI C syntax.
-pedantic Supports strict ISO/ANSI C syntax.
-w Inhibits all warning messages.
-Wimplicit Warns you whenever a local variable is unused aside from its
declaration.
gmake Maintains groups of programs.
gdb The GNU debugger program.
gas The GNU assembler program.