TAL Reference Manual

Equivalenced Variables
TAL Reference Manual—526371-001
10-10
Usage Considerations
. (period)
is the standard indirection symbol and denotes a standard (16-bit) pointer.
.EXT
is the extended indirection symbol and denotes an extended (32-bit) pointer.
identifier
is the identifier of a structure pointer to be made equivalent to previous-identifier.
referral
is the identifier of a previously declared structure or structure pointer that provides
the structure layout for
identifier.
previous-identifier
is the identifier of a previously declared simple variable, direct array element,
simple pointer, structure, structure pointer, or equivalenced 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.
offset
is an INT constant that specifies a word offset from previous-identifier, which can
be a direct or indirect variable. If
previous-identifier is indirect, the offset is from the
location of the pointer, not from the location of the data pointed to.
Usage Considerations
The STRING or INT attribute and the addressing symbol determine the kind of
addresses a structure pointer can contain, as described in Table 9-3
on page 9-7.
You can declare a structure pointer equivalent to the following previous variables.
Also, the new structure pointer and the previous pointer must both contain byte
addresses or both contain word addresses; otherwise, the pointers point to different
locations.
New Structure Pointer Previous Variable
Standard Structure Pointer Standard Indirect Structure
Standard Indirect Array
Standard Structure Pointer
Extended structure pointer Extended Indirect Structure
Extended Indirect Array
Extended Structure Pointer