LibC/gdtoa/ldtoa.c

/*  $NetBSD: ldtoa.c,v 1.4.2.1 2007/05/07 19:49:06 pavel 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  <LibConfig.h>
#include <sys/EfiCdefs.h>

#include <float.h>
#include <inttypes.h>
#include <limits.h>
#include <math.h>
#include <stdlib.h>
#include <machine/ieee.h>
#include "gdtoaimp.h"

#if defined(_MSC_VER)
  /*  Disable warnings about conversions to narrower data types,
      primarily for the fpclassify() macro.
  */
  #pragma warning ( disable : 4244 )
  // Squelch bogus warnings about uninitialized variable use.
  #pragma warning ( disable : 4700 )
#endif

/*
 * 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)
{
#ifdef EXT_EXPBITS
  static FPI fpi = {
    LDBL_MANT_DIG,      /* nbits */
    LDBL_MIN_EXP - LDBL_MANT_DIG, /* emin */
    LDBL_MAX_EXP - LDBL_MANT_DIG, /* emax */
    FPI_Round_near,           /* rounding */
#ifdef Sudden_Underflow /* unused, but correct anyway */
    1
#else
    0
#endif
  };
  int be, kind;
  char *ret;
  union ieee_ext_u u;
  uint32_t bits[(LDBL_MANT_DIG + 31) / 32];

  u.extu_ld = *ld;
  *sign = (int)(u.extu_ext.ext_sign);
  be = (int)(u.extu_ext.ext_exp - (LDBL_MAX_EXP - 1) - (LDBL_MANT_DIG - 1));
  EXT_TO_ARRAY32(u, bits);

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

  ret = gdtoa(&fpi, be, (ULong *)bits, &kind, mode, ndigits, decpt, rve);
  if (*decpt == -32768)
    *decpt = INT_MAX;
  return ret;
#else
  return dtoa((double)*ld, mode, ndigits, decpt, sign, rve);
#endif
}