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Arm Compiler armclang Reference Guide : __vfp_status intrinsic

__vfp_status intrinsic

This intrinsic reads or modifies the FPSCR.

To use this intrinsic, your source file must contain #include <arm_compat.h>. This is only available for targets in AArch32 state.


unsigned int __vfp_status(unsigned int mask, unsigned int flags)


Use this intrinsic to read or modify the flags in FPSCR.

The intrinsic returns the value of FPSCR, unmodified, if mask and flags are 0.

You can clear, set, or toggle individual flags in FPSCR using the bits in mask and flags, as shown in the following table. The intrinsic returns the modified value of FPSCR if mask and flags are not both 0.

Table 4-1 Modifying the FPSCR flags

mask bit flags bit Effect on FPSCR flag
0 0 Does not modify the flag
0 1 Toggles the flag
1 1 Sets the flag
1 0 Clears the flag


If you want to read or modify only the exception flags in FPSCR, then Arm recommends that you use the standard C99 features in <fenv.h>.


The compiler generates an error if you attempt to use this intrinsic when compiling for a target that does not have VFP.