/*      $OpenBSD: ldtoa.c,v 1.4 2016/03/09 16:28:47 deraadt Exp $       */
/*-
 * Copyright (c) 2003 David Schultz <das@FreeBSD.ORG>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <machine/ieee.h>
#include <float.h>
#include <stdint.h>
#include <limits.h>
#include <math.h>
#include <stdlib.h>
#include "gdtoaimp.h"

#if (LDBL_MANT_DIG > DBL_MANT_DIG)

/*
 * ldtoa() is a wrapper for gdtoa() that makes it smell like dtoa(),
 * except that the floating point argument is passed by reference.
 * When dtoa() is passed a NaN or infinity, it sets expt to 9999.
 * However, a long double could have a valid exponent of 9999, so we
 * use INT_MAX in ldtoa() instead.
 */
char *
__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
    char **rve)
{
        FPI fpi = {
                LDBL_MANT_DIG,                  /* nbits */
                LDBL_MIN_EXP - LDBL_MANT_DIG,   /* emin */
                LDBL_MAX_EXP - LDBL_MANT_DIG,   /* emax */
                FLT_ROUNDS,                     /* rounding */
#ifdef Sudden_Underflow /* unused, but correct anyway */
                1
#else
                0
#endif
        };
        int be, kind;
        char *ret;
        struct ieee_ext *p = (struct ieee_ext *)ld;
        uint32_t bits[(LDBL_MANT_DIG + 31) / 32];
        void *vbits = bits;

        /*
         * gdtoa doesn't know anything about the sign of the number, so
         * if the number is negative, we need to swap rounding modes of
         * 2 (upwards) and 3 (downwards).
         */
        *sign = p->ext_sign;
        fpi.rounding ^= (fpi.rounding >> 1) & p->ext_sign;

        be = p->ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1);
        EXT_TO_ARRAY32(p, bits);

        switch (fpclassify(*ld)) {
        case FP_NORMAL:
                kind = STRTOG_Normal;
#ifdef EXT_IMPLICIT_NBIT
                bits[LDBL_MANT_DIG / 32] |= 1 << ((LDBL_MANT_DIG - 1) % 32);
#endif /* EXT_IMPLICIT_NBIT */
                break;
        case FP_ZERO:
                kind = STRTOG_Zero;
                break;
        case FP_SUBNORMAL:
                kind = STRTOG_Denormal;
                be++;
                break;
        case FP_INFINITE:
                kind = STRTOG_Infinite;
                break;
        case FP_NAN:
                kind = STRTOG_NaN;
                break;
        default:
                abort();
        }

        ret = gdtoa(&fpi, be, vbits, &kind, mode, ndigits, decpt, rve);
        if (*decpt == -32768)
                *decpt = INT_MAX;
        return ret;
}
DEF_STRONG(__ldtoa);

#else   /* (LDBL_MANT_DIG == DBL_MANT_DIG) */

char *
__ldtoa(long double *ld, int mode, int ndigits, int *decpt, int *sign,
    char **rve)
{
        char *ret;

        ret = dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
        if (*decpt == 9999)
                *decpt = INT_MAX;
        return ret;
}
DEF_STRONG(__ldtoa);

#endif  /* (LDBL_MANT_DIG == DBL_MANT_DIG) */