lib/libm/frexp.c


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#include <math.h>   // for frexp
#include <stdint.h> // for uint64_t

double frexp(double x, int *e)
{
	union {
		double d;
		uint64_t i;
	} y = { x };
	int ee = y.i >> 52 & 0x7ff;

	if (!ee) {
		if (x) {
			x = frexp(x * 0x1p64, e);
			*e -= 64;
		} else
			*e = 0;
		return x;
	}
	if (ee == 0x7ff) {
		return x;
	}

	*e = ee - 0x3fe;
	y.i &= 0x800fffffffffffffull;
	y.i |= 0x3fe0000000000000ull;
	return y.d;
}