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/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*
* From: @(#)s_floor.c 5.1 93/09/24
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: s_truncl.c,v 1.4 2013/11/13 12:58:11 joerg Exp $");
#if 0
__FBSDID("$FreeBSD: head/lib/msun/src/s_truncl.c 176280 2008-02-14 15:10:34Z bde $");
#endif
/*
* truncl(x)
* Return x rounded toward 0 to integral value
* Method:
* Bit twiddling.
* Exception:
* Inexact flag raised if x not equal to truncl(x).
*/
#include "namespace.h"
#include <float.h>
#include <math.h>
#include <stdint.h>
#include <machine/ieee.h>
#ifdef __HAVE_LONG_DOUBLE
#ifdef __weak_alias
__weak_alias(truncl, _truncl)
#endif
#ifdef LDBL_IMPLICIT_NBIT
#define MANH_SIZE (EXT_FRACHBITS + 1)
#else
#define MANH_SIZE EXT_FRACHBITS
#endif
static const long double huge = 1.0e300;
static const float zero[] = { 0.0, -0.0 };
long double
truncl(long double x)
{
union ieee_ext_u ux = { .extu_ld = x, };
int e = ux.extu_exp - LDBL_MAX_EXP + 1;
if (e < MANH_SIZE - 1) {
if (e < 0) { /* raise inexact if x != 0 */
if (huge + x > 0.0)
ux.extu_ld = zero[ux.extu_sign];
} else {
uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
if (((ux.extu_frach & m) | ux.extu_fracl) == 0)
return (x); /* x is integral */
if (huge + x > 0.0) { /* raise inexact flag */
ux.extu_frach &= ~m;
ux.extu_fracl = 0;
}
}
} else if (e < LDBL_MANT_DIG - 1) {
uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
if ((ux.extu_fracl & m) == 0)
return (x); /* x is integral */
if (huge + x > 0.0) /* raise inexact flag */
ux.extu_fracl &= ~m;
}
return (ux.extu_ld);
}
#endif /* __HAVE_LONG_DOUBLE */
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