printf_fp.c

绝对正真的stdio.h的实现

/* Floating point output for `printf'.
   Copyright (C) 1995-1999,2000,2001,2002,2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Written by Ulrich Drepper <[e-mail]>, 1995.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/* The gmp headers need some configuration frobs.  */
#define HAVE_ALLOCA 1

#include <libioP.h>
#include <alloca.h>
#include <ctype.h>
#include <float.h>
#include <gmp-mparam.h>
#include <gmp.h>
#include <stdlib/gmp-impl.h>
#include <stdlib/longlong.h>
#include <stdlib/fpioconst.h>
#include <locale/localeinfo.h>
#include <limits.h>
#include <math.h>
#include <printf.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <wchar.h>

#ifdef COMPILE_WPRINTF
# define CHAR_T        wchar_t
#else
# define CHAR_T        char
#endif

#include "_i18n_number.h"

#ifndef NDEBUG
# define NDEBUG			/* Undefine this for debugging assertions.  */
#endif
#include <assert.h>

/* This defines make it possible to use the same code for GNU C library and
   the GNU I/O library.	 */
#define PUT(f, s, n) _IO_sputn (f, s, n)
#define PAD(f, c, n) (wide ? _IO_wpadn (f, c, n) : INTUSE(_IO_padn) (f, c, n))
/* We use this file GNU C library and GNU I/O library.	So make
   names equal.	 */
#undef putc
#define putc(c, f) (wide \
		    ? (int)_IO_putwc_unlocked (c, f) : _IO_putc_unlocked (c, f))
#define size_t     _IO_size_t
#define FILE	     _IO_FILE

/* Macros for doing the actual output.  */

#define outchar(ch)							      \
  do									      \
    {									      \
      register const int outc = (ch);					      \
      if (putc (outc, fp) == EOF)					      \
	return -1;							      \
      ++done;								      \
    } while (0)

#define PRINT(ptr, wptr, len)						      \
  do									      \
    {									      \
      register size_t outlen = (len);					      \
      if (len > 20)							      \
	{								      \
	  if (PUT (fp, wide ? (const char *) wptr : ptr, outlen) != outlen)   \
	    return -1;							      \
	  ptr += outlen;						      \
	  done += outlen;						      \
	}								      \
      else								      \
	{								      \
	  if (wide)							      \
	    while (outlen-- > 0)					      \
	      outchar (*wptr++);					      \
	  else								      \
	    while (outlen-- > 0)					      \
	      outchar (*ptr++);						      \
	}								      \
    } while (0)

#define PADN(ch, len)							      \
  do									      \
    {									      \
      if (PAD (fp, ch, len) != len)					      \
	return -1;							      \
      done += len;							      \
    }									      \
  while (0)

/* We use the GNU MP library to handle large numbers.

   An MP variable occupies a varying number of entries in its array.  We keep
   track of this number for efficiency reasons.  Otherwise we would always
   have to process the whole array.  */
#define MPN_VAR(name) mp_limb_t *name; mp_size_t name##size

#define MPN_ASSIGN(dst,src)						      \
  memcpy (dst, src, (dst##size = src##size) * sizeof (mp_limb_t))
#define MPN_GE(u,v) \
  (u##size > v##size || (u##size == v##size && __mpn_cmp (u, v, u##size) >= 0))

extern int __isinfl_internal (long double) attribute_hidden;
extern int __isnanl_internal (long double) attribute_hidden;

extern mp_size_t __mpn_extract_double (mp_ptr res_ptr, mp_size_t size,
				       int *expt, int *is_neg,
				       double value);
extern mp_size_t __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
					    int *expt, int *is_neg,
					    long double value);
extern unsigned int __guess_grouping (unsigned int intdig_max,
				      const char *grouping);


static wchar_t *group_number (wchar_t *buf, wchar_t *bufend,
			      unsigned int intdig_no, const char *grouping,
			      wchar_t thousands_sep, int ngroups)
     internal_function;


int
__printf_fp (FILE *fp,
	     const struct printf_info *info,
	     const void *const *args)
{
  /* The floating-point value to output.  */
  union
    {
      double dbl;
      __long_double_t ldbl;
    }
  fpnum;

  /* Locale-dependent representation of decimal point.	*/
  const char *decimal;
  wchar_t decimalwc;

  /* Locale-dependent thousands separator and grouping specification.  */
  const char *thousands_sep = NULL;
  wchar_t thousands_sepwc = 0;
  const char *grouping;

  /* "NaN" or "Inf" for the special cases.  */
  const char *special = NULL;
  const wchar_t *wspecial = NULL;

  /* We need just a few limbs for the input before shifting to the right
     position.	*/
  mp_limb_t fp_input[(LDBL_MANT_DIG + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB];
  /* We need to shift the contents of fp_input by this amount of bits.	*/
  int to_shift = 0;

  /* The fraction of the floting-point value in question  */
  MPN_VAR(frac);
  /* and the exponent.	*/
  int exponent;
  /* Sign of the exponent.  */
  int expsign = 0;
  /* Sign of float number.  */
  int is_neg = 0;

  /* Scaling factor.  */
  MPN_VAR(scale);

  /* Temporary bignum value.  */
  MPN_VAR(tmp);

  /* Digit which is result of last hack_digit() call.  */
  wchar_t digit;

  /* The type of output format that will be used: 'e'/'E' or 'f'.  */
  int type;

  /* Counter for number of written characters.	*/
  int done = 0;

  /* General helper (carry limb).  */
  mp_limb_t cy;

  /* Nonzero if this is output on a wide character stream.  */
  int wide = info->wide;

  auto wchar_t hack_digit (void);

  wchar_t hack_digit (void)
    {
      mp_limb_t hi;

      if (expsign != 0 && type == 'f' && exponent-- > 0)
	hi = 0;
      else if (scalesize == 0)
	{
	  hi = frac[fracsize - 1];
	  frac[fracsize - 1] = __mpn_mul_1 (frac, frac, fracsize - 1, 10);
	}
      else
	{
	  if (fracsize < scalesize)
	    hi = 0;
	  else
	    {
	      hi = mpn_divmod (tmp, frac, fracsize, scale, scalesize);
	      tmp[fracsize - scalesize] = hi;
	      hi = tmp[0];

	      fracsize = scalesize;
	      while (fracsize != 0 && frac[fracsize - 1] == 0)
		--fracsize;
	      if (fracsize == 0)
		{
		  /* We're not prepared for an mpn variable with zero
		     limbs.  */
		  fracsize = 1;
		  return L'0' + hi;
		}
	    }

	  mp_limb_t _cy = __mpn_mul_1 (frac, frac, fracsize, 10);
	  if (_cy != 0)
	    frac[fracsize++] = _cy;
	}

      return L'0' + hi;
    }


  /* Figure out the decimal point character.  */
  if (info->extra == 0)
    {
      decimal = _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
      decimalwc = _NL_CURRENT_WORD (LC_NUMERIC, _NL_NUMERIC_DECIMAL_POINT_WC);
    }
  else
    {
      decimal = _NL_CURRENT (LC_MONETARY, MON_DECIMAL_POINT);
      if (*decimal == '\0')
	decimal = _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
      decimalwc = _NL_CURRENT_WORD (LC_MONETARY,
				    _NL_MONETARY_DECIMAL_POINT_WC);
      if (decimalwc == L'\0')
	decimalwc = _NL_CURRENT_WORD (LC_NUMERIC,
				      _NL_NUMERIC_DECIMAL_POINT_WC);
    }
  /* The decimal point character must not be zero.  */
  assert (*decimal != '\0');
  assert (decimalwc != L'\0');

  if (info->group)
    {
      if (info->extra == 0)
	grouping = _NL_CURRENT (LC_NUMERIC, GROUPING);
      else
	grouping = _NL_CURRENT (LC_MONETARY, MON_GROUPING);

      if (*grouping <= 0 || *grouping == CHAR_MAX)
	grouping = NULL;
      else
	{
	  /* Figure out the thousands separator character.  */
	  if (wide)
	    {
	      if (info->extra == 0)
		thousands_sepwc =
		  _NL_CURRENT_WORD (LC_NUMERIC, _NL_NUMERIC_THOUSANDS_SEP_WC);
	      else
		thousands_sepwc =
		  _NL_CURRENT_WORD (LC_MONETARY,
				    _NL_MONETARY_THOUSANDS_SEP_WC);
	    }
	  else
	    {
	      if (info->extra == 0)
		thousands_sep = _NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP);
	      else
		thousands_sep = _NL_CURRENT (LC_MONETARY, MON_THOUSANDS_SEP);
	    }

	  if ((wide && thousands_sepwc == L'\0')
	      || (! wide && *thousands_sep == '\0'))
	    grouping = NULL;
	  else if (thousands_sepwc == L'\0')
	    /* If we are printing multibyte characters and there is a
	       multibyte representation for the thousands separator,
	       we must ensure the wide character thousands separator
	       is available, even if it is fake.  */
	    thousands_sepwc = 0xfffffffe;
	}
    }
  else
    grouping = NULL;

  /* Fetch the argument value.	*/
#ifndef __NO_LONG_DOUBLE_MATH
  if (info->is_long_double && sizeof (long double) > sizeof (double))
    {
      fpnum.ldbl = *(const long double *) args[0];

      /* Check for special values: not a number or infinity.  */
      if (__isnanl (fpnum.ldbl))
	{
	  if (isupper (info->spec))
	    {
	      special = "NAN";
	      wspecial = L"NAN";
	    }
	    else
	      {
		special = "nan";
		wspecial = L"nan";
	      }
	  is_neg = 0;
	}
      else if (__isinfl (fpnum.ldbl))
	{
	  if (isupper (info->spec))
	    {
	      special = "INF";
	      wspecial = L"INF";
	    }
	  else
	    {
	      special = "inf";
	      wspecial = L"inf";
	    }
	  is_neg = fpnum.ldbl < 0;
	}
      else
	{
	  fracsize = __mpn_extract_long_double (fp_input,
						(sizeof (fp_input) /
						 sizeof (fp_input[0])),
						&exponent, &is_neg,
						fpnum.ldbl);
	  to_shift = 1 + fracsize * BITS_PER_MP_LIMB - LDBL_MANT_DIG;
	}
    }
  else
#endif	/* no long double */
    {
      fpnum.dbl = *(const double *) args[0];

      /* Check for special values: not a number or infinity.  */
      if (__isnan (fpnum.dbl))
	{
	  is_neg = 0;
	  if (isupper (info->spec))
	    {
	      special = "NAN";
	      wspecial = L"NAN";
	    }
	  else
	    {
	      special = "nan";
	      wspecial = L"nan";
	    }
	}
      else if (__isinf (fpnum.dbl))
	{
	  is_neg = fpnum.dbl < 0;
	  if (isupper (info->spec))
	    {
	      special = "INF";
	      wspecial = L"INF";
	    }
	  else
	    {
	      special = "inf";
	      wspecial = L"inf";
	    }
	}
      else
	{
	  fracsize = __mpn_extract_double (fp_input,
					   (sizeof (fp_input)
					    / sizeof (fp_input[0])),
					   &exponent, &is_neg, fpnum.dbl);
	  to_shift = 1 + fracsize * BITS_PER_MP_LIMB - DBL_MANT_DIG;
	}
    }

  if (special)
    {
      int width = info->width;

      if (is_neg || info->showsign || info->space)
	--width;
      width -= 3;

      if (!info->left && width > 0)
	PADN (' ', width);

      if (is_neg)
	outchar ('-');
      else if (info->showsign)
	outchar ('+');