RealView Compilation Tools Assembler Guide: 7.8.8. EXPORT or GLOBAL

7.8.8. EXPORT or GLOBAL

The EXPORT directive declares a symbol that can be used by the linker to resolve symbol references in separate object and library files. GLOBAL is a synonym for EXPORT.

Syntax

EXPORT {[WEAK]}

EXPORT symbol {[type]}

EXPORT symbol [attr{,type}]

EXPORT symbol [WEAK{,attr}{,type}]

where:

symbol

is the symbol name to export. The symbol name is case-sensitive. If symbol is omitted, all symbols are exported.

WEAK

symbol is only imported into other sources if no other source exports an alternative symbol. If [WEAK] is used without symbol, all exported symbols are weak.

attr

can be any one of:

DYNAMIC: sets the ELF symbol visibility to STV_DEFAULT.
PROTECTED: sets the ELF symbol visibility to STV_PROTECTED.
HIDDEN: sets the ELF symbol visibility to STV_HIDDEN.
INTERNAL: sets the ELF symbol visibility to STV_INTERNAL.

type

specifies the symbol type:

DATA: symbol is treated as data when the source is assembled and linked.
CODE: symbol is treated as code when the source is assembled and linked.
ELFTYPE=n: symbol is treated as a particular ELF symbol, as specified by the value of n, where n can be any number from 0 to 15.

If unspecified, the assembler determines the most appropriate type.

Usage

Use EXPORT to give code in other files access to symbols in the current file.

Use the [WEAK] attribute to inform the linker that a different instance of symbol takes precedence over this one, if a different one is available from another source. You can use the [WEAK] attribute with any of the symbol visibility attributes.

Example

        AREA    Example,CODE,READONLY
        EXPORT  DoAdd           ; Export the function name
                                ; to be used by external
                                ; modules.
DoAdd   ADD     r0,r0,r1

Symbol visibility can be overridden for duplicate exports. In the following example, the last EXPORT takes precedence for both binding and visibility:

        EXPORT  SymA[WEAK]      ; Export as weak-hidden
        EXPORT  SymA[DYNAMIC]   ; SymA becomes non-weak dynamic.

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