HP C A.06.05 Reference Manual

Compiling and Running HP C Programs

Pragmas

Chapter 9228

For example, the following command builds the name $CODE&MINE$:

#pragma locality “mine”

Code that is not headed by a LOCALITY pragma is associated with the name $CODE$. An empty

string

" causes the code name to revert to the default name of $CODE$.

VERSIONID Pragma

#pragma VERSIONID "

string

Speciﬁes a version string to be associated with a particular piece of code. The

string

is placed

into the object ﬁle produced when the code is compiled.

Data Alignment Pragmas

This section discusses the data alignment pragmas HP_ALIGN and PACK and their various

arguments available on the HP-UX systems, to control alignment across platforms. In the

following discussion, a word represents a 32-bit data structure. Refer to HP aC++/HP C

Programmer's Guide for detailed information on the HP_ALIGN and PACK pragmas.

ALIGN Pragma

#pragma align N

N is a number raised to the power of 2.

HP aC++ supports user speciﬁed alignment for global data. The pragma takes effect on next

declaration. If the align pragma declaration is not in the global scope or if it is not a data

declaration, the compiler displays a warning message. If the speciﬁed alignment is lesser than

the original alignment of data, a warning message is displayed, and the pragma is ignored.

#pragma align 2

char c; // "c" is at least aligned on 2 byte boundary

#pragma align 64

int i, a[10]; // "i" and array "a" are at least aligned 64 byte boundary.

// the size of "a" is still 10*sizeof(int)

PACK Pragma

#pragma PACK

The PACK pragma is a simple, intuitive way for users to specify alignment. In the syntax,

the byte boundary on which members of structs and unions should be aligned, and can be 1, 2,

4, 8, or 16.