7.7.12. IMPORT

The IMPORT directive provides the assembler with a name that is not defined in the current assembly.

IMPORT is very similar to EXTERN, except that the name is imported whether or not it is referred to in the current assembly (see EXTERN, and EXPORT or GLOBAL).

Syntax

IMPORT symbol{[WEAK]}

where:

symbol

is a symbol name defined in a separately assembledsource file, object file, or library. The symbol name is case-sensitive.

WEAK

prevents the linker generating an error message if the symbol is not defined elsewhere. It also prevents the linker searching libraries that are not already included.

Usage

The name is resolved at link time to a symbol defined in a separate object file. The symbol is treated as a program address. If [WEAK] is not specified, the linker generates an error if no corresponding symbol is found at link time.

If [WEAK] is specified and no corresponding symbol is found at link time:

  • If the reference is the destination of a B or BL instruction, the value of the symbol is taken as the address of the following instruction. This makes the B or BL instruction effectively a NOP.

  • Otherwise, the value of the symbol is taken as zero.

To avoid trying to access symbols that are not found at link time, use code like the example in EXTERN.

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