15.25 ENTRY

The ENTRY directive declares an entry point to a program.

Syntax

ENTRY

Usage

A program must have an entry point. You can specify an entry point in the following ways:

  • Using the ENTRY directive in assembly language source code.

  • Providing a main() function in C or C++ source code.

  • Using the armlink --entry command-line option.

You can declare more than one entry point in a program, although a source file cannot contain more than one ENTRY directive. For example, a program could contain multiple assembly language source files, each with an ENTRY directive. Or it could contain a C or C++ file with a main() function and one or more assembly source files with an ENTRY directive.

If the program contains multiple entry points, then you must select one of them. You do this by exporting the symbol for the ENTRY directive that you want to use as the entry point, then using the armlink --entry option to select the exported symbol.

Example

        AREA   ARMex, CODE, READONLY
        ENTRY      ; Entry point for the application.
        EXPORT ep1 ; Export the symbol so the linker can find it
ep1                ; in the object file.
        ; code
        END

When you invoke armlink, if other entry points are declared in the program, then you must specify --entry=ep1, to select ep1.

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