This intrinsic enables FIQ interrupts.
To use this intrinsic, your source file must contain
#include <arm_compat.h>. This is only available
for targets in AArch32 state.
NoteTypically, this intrinsic enables FIQ interrupts by clearing the F-bit in the CPSR. However, for v7-M and v8-M.mainline, it clears the fault mask register (FAULTMASK). This intrinsic is not supported in v6-M and v8-M.baseline.
__enable_fiq intrinsic can only be executed in privileged modes, that is, in non-user modes. In User mode, this intrinsic does not change the interrupt flags in the