/*
 * ====================================================
 * 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.
 * ====================================================
 */

/*
 * 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 <float.h>
#include <math.h>
#include <stdint.h>

#include "fpmath.h"

#ifdef LDBL_IMPLICIT_NBIT
#define MANH_SIZE       (LDBL_MANH_SIZE + 1)
#else
#define MANH_SIZE       LDBL_MANH_SIZE
#endif

static const long double huge = 1.0e300;
static const float zero[] = { 0.0, -0.0 };

long double
truncl(long double x)
{
        union IEEEl2bits u = { .e = x };
        int e = u.bits.exp - LDBL_MAX_EXP + 1;

        if (e < MANH_SIZE - 1) {
                if (e < 0) {                    /* raise inexact if x != 0 */
                        if (huge + x > 0.0)
                                u.e = zero[u.bits.sign];
                } else {
                        uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
                        if (((u.bits.manh & m) | u.bits.manl) == 0)
                                return (x);     /* x is integral */
                        if (huge + x > 0.0) {   /* raise inexact flag */
                                u.bits.manh &= ~m;
                                u.bits.manl = 0;
                        }
                }
        } else if (e < LDBL_MANT_DIG - 1) {
                uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
                if ((u.bits.manl & m) == 0)
                        return (x);     /* x is integral */
                if (huge + x > 0.0)             /* raise inexact flag */
                        u.bits.manl &= ~m;
        }
        return (u.e);
}

#if LDBL_MANT_DIG == 113
__weak_reference(truncl, truncf128);
#endif