Cirrus Logic CS485 Bedienungsanleitung PDF herunterladen (Seite 37)

CS485G Spring 2015 37

4. Global symbols: deﬁned in this module, may be referenced by other

modules. In C: functions (except static) and ﬁle-global variables

(except static).

5. External symbols: global symbols referenced by this module but de-

ﬁned in another module.

6. Local symbols: symbols deﬁned and referenced only within this

module. In C: functions and ﬁle-global variables deﬁned static.

The object ﬁle does not even name variables declared within func-

tions. extern.

39 Unix tools for object ﬁles

1. ar: creates static libraries

2. strings: lists printable strings in any ﬁle

3. strip: deletes symbol-table information from an object ﬁle, so it is

no longer linkable.

4. nm: list the symbol table of an object ﬁle

5. size: show the names and sizes of the sections of an object ﬁle

6. readelf: display the content of an object ﬁle

7. objdump: show the names and sizes of the sections of an object ﬁle

8. ldd: show the dynamically-linked libraries this object ﬁle needs

40 Resolving multiple deﬁnitions of the same sym-

bol

1. Strong symbols are procedures and initialized global variables.

2. Weak symbols are uninitialized global variables.

3. Multiple strong symbols are an error.

4. A single strong symbol is equated to all weak occurrences. This

choice can lead to errors if the variable is declared of different types

in different compilation units.

5. Multiple weak symbols are allowed; one is chosen. This choice is

also error-prone.

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Cirrus Logic CS485 Bedienungsanleitung Seite 37