9.137 __strexd intrinsic
__strexd intrinsic lets you use an
STREXD instruction in your C or C++ code to perform an exclusive doubleword data store to memory.
NoteThe compiler does not guarantee to preserve the state of the exclusive
monitor. It might generate load and store instructions between the
LDREXD instruction generated for the
intrinsic and the
STREXD instruction generated for the
__strexd intrinsic. Because memory accesses can clear the
exclusive monitor, code using the
__strexd intrinsics can have unexpected behavior. Where
are needed, ARM recommends using embedded assembly.
int __strexd(unsigned long long
val, volatile void
is the value to be written to memory.
points to the address of the data to be written to in memory. To specify the size
of the data to be written, cast the parameter to an appropriate integral type.
Table 9-12 Access widths that the __strexd intrinsic supports
||Size of data stored
long long *
__strexd intrinsic returns:
STREXD instruction succeeds
STREXD instruction is locked out.
The compiler does not recognize the
__strexd intrinsic when compiling for a
target that does not support the
STREXD instruction. The compiler generates
either a warning or an error in this case, depending on the source language:
- In C code:
Warning: #223-D: function "__strexd" declared implicitly.
- In C++ code:
Error: #20: identifier "__strexd" is undefined.
__strexd intrinsic only supports access to doubleword data. The
compiler generates an error if you specify an access width that is not supported.