HP 3000 Manuals HP 3000 Manuals
Porting between HP C and Domain/C
All HP-UX and Domain computers have ANSI C compilers. Strictly
standard-compliant programs are highly portable between all these
architectures.
The following Domain/C extensions are not supported on HP-UX in
compatibility mode and in most cases, are not supported in ANSI mode
either:
* Reference variables.
* The following preprocessor directives: #attribute, #options,
#section, #module, #debug, #eject, #list, #nolist, and #systype.
* std_$call.
* __attribute modifier and __options specifier.
* systype predefined macro.
* _BFMT__COFF predefined macro.
* _ISP__M68K predefined macro.
* _ISP__A88K predefined macro.
* _ISP__PA_RISC predefined macro.
* Partial specification of struct and union members.
Function prototypes, struct and union initialization, and the predefined
names __DATE__ and __TIME__, all of which are ANSI C features, are
supported on HP-UX in ANSI mode.
Compile line options are different between HP-UX C and Domain/C. Check
the respective cc(1) page for complete descriptions.
There are other differences between HP-UX C and Domain/C:
* Alignment: All Domain workstations have hardware or software
assists to handle misaligned data. Programs that rely on these
features will not run on the Series 800.
* Floating-point exceptions: All Domain workstations, by default,
enable invalid operation, divide by zero, and overflow exception
traps. Programs that rely on fault detection, for instance, to
enter a fault handler or to terminate execution on encountering a
fault, will ordinarily generate useless output on HP-UX. However,
the PA1.1 math library for the Series 700/800 provides a function
fpsetdefaults(3M), which enables these traps and therefore allows
such programs to run as expected. For more information, see the
HP-UX Floating-Point Guide.
* struct layout and alignment, especially bit-field, is different.
* float data type: Domain/C optimizes a statement all of whose
atoms are float or floating-point constants, to be evaluated in
float rather than double.
* register declarations: Domain/C completely ignores register
declarations, except to ensure that language constraints are not
violated.
* Include file search rules are different.
* Programs that rely on undefined behaviors, for instance, the order
of expression evaluation and the application of unsequenced
side-effects, will probably execute differently.