Intel XENIX 286 Programmers Guide (86) - Tenox.tc

Programming Commands XENIX Programming
CC (continued)
In middle, large, and huge model programs, function pointers are 32 bits long. In large
and huge model programs, data pointers are 32 bits long. Programs making use of such
pointers must be written carefully to avoid incorrect declaration and use of these types.
lint will help to check for correct use.
Keep the following in mind when programming in huge model.
Objects
No object can cross a segment boundary. Objects are defined as data structures
that can be elements of an array, scalar objects (integers and floating point
numbers), and composite obj ects (structures and unions). If the array requires
three or more segments (more than 128K bytes), then the size of the objects in
the array must be a power of two.
Address Space
When accessing a huge model array, the compiler simulates a linear address
space.
Array Align ment
Arrays of objects requiring more than one segment are aligned so that no object
crosses a 64K-byte boundary.
Pointer Size
Another item to be considered when programming in huge model is the value
produced by sizeof(huge item) and sizeof(huge ptrl - huge ptr2). To obtain the
correct value, sizeof must be type cast as a lon - -
g
(long)sizeof(huge item)
(long)sizeof(huge =ptrl - huge _ptr2)
where the value returned is a long instead of a normal integer.
The -NM, -NT, and -ND options may be used with middle, large, and huge model
programs to direct the text and data of specific object files to named physical
segments. All text having the same text segment name is placed in a single physical
segment. Similarly, all data having the same data segment name is placed in a single
physical segment.
Files
/bin/cc, /lib/pO, /lib/pl, /lib/p2, /lib/p3
See Also
as, ar, ld, lint, ranlib
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