This intrinsic inserts a VABS instruction or an equivalent code sequence into the instruction stream generated by the compiler. It enables you to obtain the absolute value of a double‑precision floating‑point value from within your C or C++ code.
Note
The __fabs intrinsic is an analogue of the standard C library function fabs. It differs from the standard library function in that a call to __fabs is guaranteed to be compiled into a single, inline, machine instruction on an ARM architecture‑based processor equipped with a VFP coprocessor.
double __fabs(double val)
Where:
valis a double‑precision floating‑point value.
The __fabs intrinsic returns the absolute value of val as a double.