__ldrexd intrinsic lets you load doubleword data from memory in your C or C++ code using an
NoteThe compiler does not guarantee that it will preserve the state of the exclusive monitor. It may generate load and store instructions between the
LDREXDinstruction generated for the
__ldrexdintrinsic and the
STREXDinstruction generated for the
__strexdintrinsic. Because memory accesses can clear the exclusive monitor, code using the
__strexdintrinsics can have unexpected behavior. Where
STREXDinstructions are needed, ARM recommends using embedded assembly.
unsigned long long __ldrexd(volatile void *ptr)
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 10-9 Access widths that the __ldrex intrinsic supports
Instruction Size of data loaded Pointer type
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.