9.116 __ldrexd intrinsic
__ldrexd intrinsic lets you load doubleword data from memory in your C or C++ code using an
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.
unsigned long long __ldrexd(volatile void *
points to the address of the data to be loaded from memory. To specify the type of
the data to be loaded, cast the parameter to an appropriate pointer type.
Table 9-9 Access widths that the __ldrex intrinsic supports
||Size of data loaded
long long *
__ldrexd intrinsic returns the data loaded from the memory address
pointed to by
The compiler does not recognize the
__ldrexd intrinsic when compiling for a
target that does not support the
LDREXD 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 "__ldrexd" declared implicitly.
- In C++ code:
Error: #20: identifier "__ldrexd" is undefined.
__ldrexd intrinsic only supports access to doubleword data. The
compiler generates an error if you specify an access width that is not supported.