lib/libm/roundf.c


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#include "libm.h"

#if FLT_EVAL_METHOD == 0
#define EPS FLT_EPSILON
#elif FLT_EVAL_METHOD == 1
#define EPS DBL_EPSILON
#elif FLT_EVAL_METHOD == 2
#define EPS LDBL_EPSILON
#endif
static const float_t toint = 1 / EPS;

float roundf(float x)
{
	union {
		float f;
		uint32_t i;
	} u = { x };
	int e = u.i >> 23 & 0xff;
	float_t y;

	if (e >= 0x7f + 23)
		return x;
	if (u.i >> 31)
		x = -x;
	if (e < 0x7f - 1) {
		FORCE_EVAL(x + toint);
		return 0 * u.f;
	}
	y = x + toint - toint - x;
	if (y > 0.5f)
		y = y + x - 1;
	else if (y <= -0.5f)
		y = y + x + 1;
	else
		y = y + x;
	if (u.i >> 31)
		y = -y;
	return y;
}