9.10.19 sfr
(address)
The sfr attribute tells the compiler that the variable
is an SFR and may also specify the run-time address of the variable, using the
address parameter.
extern volatile int __attribute__
((sfr(0x200)))u1mod;
The use of the extern specifier is required in order to
not produce an error.
Note: By convention, the
sfr attribute is used
only in processor header files. To define a general user variable at a specific address
use the address attribute in conjunction with near or
far to specify the correct addressing mode.