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Compiler-specific Features
Where:
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 4-8 Access widths supported by the __ldrex intrinsic
Instruction Size of data loaded C cast
LDREXB unsigned byte (unsigned char *)
LDREXB signed byte (signed char *)
LDREXH unsigned halfword (unsigned short *)
LDREXH signed halfword (short *)
LDREX word (int *)
Return value
The __ldrex intrinsic returns the data loaded from the memory address pointed to by
ptr.
Errors
The compiler does not recognize the __ldrex intrinsic when compiling for a target that
does not support the LDREX instruction. The compiler generates either a warning or an
error in this case.
The __ldrex intrinsic does not support access to doubleword data. The compiler
generates an error if you specify an access width that is not supported.
Example
int foo(void)
{
int loc = 0xff;
return __ldrex((volatile char *)loc);
}
Compiling this code with the command-line option --cpu=6k produces
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