pTAL Reference Manual (H06.08+)

Equivalenced Variables

HP pTAL Reference Manual—523746-006

11-9

Equivalenced Simple Variables

VOLATILE

specifies that the value of this variable must be maintained in memory, not in a

or written to memory even when code is optimized. Based on the order of reads

and writes in the source code, VOLATILE also causes that precise order of

memory references to be preserved, again, when code is optimized.

type

If referral is present, type must be STRING or INT; otherwise, type is any

data type except UNSIGNED.

identifier

is the identifier of the simple equivalenced variable to be made equivalent to

previous-identifier.

previous-identifier

is the identifier of a previously declared simple variable.

index

is an INT constant that specifies an element offset from previous-identifier,

which must be a direct variable. The data type of previous-identifier

dictates the element size. The location represented by index must begin on a

word boundary.

is the word or byte offset, relative to the base of previous-ident, where the

equivalenced variable is placed. For example, if a and b are declared:

INT(32) a[0:9];

INT b = a+6

then b is placed in the first six bits of a.

offset

is an INT constant that specifies an element offset from previous-identifier,

which must be a direct variable. The data type of previous-identifier

dictates the element size. The location represented by index must begin on a

word boundary.

Equivalencing a simple variable to an indirect array or structure is not recommended. If

you do so, the simple variable is made equivalent to the location of the implicit pointer,

not the location of the data pointed to.

In Figure 11-2 on page 11-10, a STRING variable and an INT(32) variable are

equivalenced to an INT array.