Porting between HP C and Domain/C

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.

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 workstations and servers 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.