Commodore PC - Page 277

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If a segment has a common combine type, the linker combines it
^*. automatically with any other segments that have the same name
' ' and belong to the same class. When link combines common seg
ments, however, it places the start of each segment at the same
address, creating a series of overlapping segments. The result
(***) is a single segment no larger than the largest of the combined
segments.
^^^ The linker treats segments with memory combine types exactly
(\ like segments with public combine types. The Microsoft Macro
Assembler (masm), provides combine type memory for compatibil
ity with linkers that support a separate combine type for memory
/^■^ segments.
A segment has a private combine type only if no explicit combine
type is defined for it in the source file. Link does not combine
f**} private segments.
Groups
Groups permit noncontiguous segments that do not belong to the
same class to be addressable relative to the same frame address.
When link encounters a group, it adjusts all memory references
to items in the group so that they are relative to the same frame
address.
Segments in a group do not have to be contiguous and do not
have to belong to the same class. Nor do they have to have the
same combine type. The only requirement is that all segments in
the group fit within 64K bytes.
Groups do not affect the order in which the segments are loaded.
Unless you use class names and enter object files in the right
order, there is no guarantee that the segments will be contiguous.
In fact, the linker may place segments that do not belong to the
group in the same 64K bytes of memory. Although link does not
explicitly check whether all segments in a group fit within this
f0**} 64K of memory, the linker is likely to encounter a fixup-overflow
error if this requirement is not met.
Groups, and how to define them, are discussed further in the
("**) Microsoft Macro Assembler Reference Manual.
Fixups
Once the starting address of each segment in a program is known,
and all segment combinations and groups have been established,
/0ms^ the linker can fix up any unresolved references to labels and vari-
' ^ ables. To fix up unresolved references, the linker computes an
appropriate offset and segment address and replaces the tem
porary values, generated by the assembler, with the new values.
Common combine
types
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Memory combine
types
Private combine types
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