5.6 Directives that Reference Other Files
These directives supply information for or about other files that can be used in the assembly of the current file:
- The .copy and .include directives tell the assembler to begin reading source statements from another file. When the assembler finishes reading the source statements in the copy/include file, it resumes reading source statements from the current file. The statements read from a copied file are printed in the listing file; the statements read from an included file are not printed in the listing file.
- The .def directive identifies a symbol that is defined in the current module and that can be used in another module. The assembler includes the symbol in the symbol table.
- The .global directive declares a symbol external so that it is available to other modules at link time. (For more information about global symbols, see Section 2.6.1). The .global directive does double duty, acting as a .def for defined symbols and as a .ref for undefined symbols. The linker resolves an undefined global symbol reference only if the symbol is used in the program. The .global directive declares a 16-bit symbol.
- The .mlib directive supplies the assembler with the name of an archive library that contains macro definitions. When the assembler encounters a macro that is not defined in the current module, it searches for it in the macro library specified with .mlib.
- The .ref directive identifies a symbol that is used in the current module but is defined in another module. The assembler marks the symbol as an undefined external symbol and enters it in the object symbol table so the linker can resolve its definition. The .ref directive forces the linker to resolve a symbol reference.
- The .symdepend directive creates an artificial reference from the section defining the source symbol name to the destination symbol. The .symdepend directive prevents the linker from removing the section containing the destination symbol if the source symbol section is included in the output module.
- The .weak directive identifies a symbol that is used in the current module but is defined in another module. It is equivalent to the .ref directive, except that the reference has weak linkage.