lib/libm/__fpclassify.c


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#include <math.h>
#include <stdint.h>

int __fpclassify(double x)
{
	union {
		double f;
		uint64_t i;
	} u = { x };
	int e = u.i >> 52 & 0x7ff;
	if (!e)
		return u.i << 1 ? FP_SUBNORMAL : FP_ZERO;
	if (e == 0x7ff)
		return u.i << 12 ? FP_NAN : FP_INFINITE;
	return FP_NORMAL;
}