root/src/system/libroot/posix/musl/math/arm/sqrtf.c 
#include <math.h>

#if (__ARM_PCS_VFP || (__VFP_FP__ && !__SOFTFP__)) && !BROKEN_VFP_ASM

float sqrtf(float x)
{
        __asm__ ("vsqrt.f32 %0, %1" : "=t"(x) : "t"(x));
        return x;
}

#else

#include "../sqrtf.c"

#endif