Using the GNU Compiler Collection (GCC): Asm Labels

Next: Explicit Register Variables, Previous: Constraints, Up: Using Assembly Language with C [Contents][Index]

#### 6.44.4 Controlling Names Used in Assembler Code

You can specify the name to be used in the assembler code for a C function or variable by writing the `asm` (or `__asm__`) keyword after the declarator. It is up to you to make sure that the assembler names you choose do not conflict with any other assembler symbols, or reference registers.

#### Assembler names for data:

This sample shows how to specify the assembler name for data:

    int foo asm ("myfoo") = 2;

This specifies that the name to be used for the variable `foo` in the assembler code should be ‘`myfoo`’ rather than the usual ‘`_foo`’.

On systems where an underscore is normally prepended to the name of a C variable, this feature allows you to define names for the linker that do not start with an underscore.

GCC does not support using this feature with a non-static local variable since such variables do not have assembler names. If you are trying to put the variable in a particular register, see Explicit Register Variables.

#### Assembler names for functions:

To specify the assembler name for functions, write a declaration for the function before its definition and put `asm` there, like this:

    int func (int x, int y) asm ("MYFUNC");

    int func (int x, int y)
    {
       /* … */

This specifies that the name to be used for the function `func` in the assembler code should be `MYFUNC`.

Next: Explicit Register Variables, Previous: Constraints, Up: Using Assembly Language with C [Contents][Index]