outfloat.c

vxworks源码源码解读是学习vxworks的最佳途径

/* This has been copied from the gnu source tree */
/* Make all changes there, not here! */
#ifdef __cplusplus
extern "C" {
#endif
#ifndef _N_
char __outfloat_o = 0;
#else
char _N_ = 0;
#endif
#ifdef __cplusplus
}
#endif
#include "vxWorks.h"
/* 
Copyright (C) 1993 Free Software Foundation

This file is part of the GNU IO Library.  This library is free
software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option)
any later version.

This 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this library; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

As a special exception, if you link this library with files
compiled with a GNU compiler to produce an executable, this does not cause
the resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why
the executable file might be covered by the GNU General Public License. */

#include "libioP.h"

#ifdef _IO_USE_DTOA
/* Format floating-point number and print them.
   Return number of chars printed, or EOF on error.

   sign_mode == '+' : print "-" or "+"
   sign_mode == ' ' : print "-" or " "
   sign_mode == '\0' : print "-' or ""
*/

int
_IO_outfloat (value, sb, type, width, precision, flags, sign_mode, fill)
     double value;
     _IO_FILE *sb;
     int type;
     int width;
     int precision;
     int flags;
     int sign_mode;
     int fill;
{
  int count = 0;
#define PUT(x) do {if (_IO_putc(x, sb) < 0) goto error; count++;} while (0)
#define PUTN(p, n) \
  do {int _n=n; count+=_n; if (_IO_sputn(sb, p,_n) != _n) goto error;} while(0)
#define PADN(fill, n) \
  do {int _n = n; count+=_n; if (_IO_padn(sb, fill, _n) != _n) goto error;} while (0)
  int pad_kind = flags & (_IO_LEFT|_IO_RIGHT|_IO_INTERNAL);
  int skip_zeroes = 0;
  int show_dot = (flags & _IO_SHOWPOINT) != 0;
  int decpt;
  int sign;
  int mode;
  int exponent_size;
  int print_sign;
  int trailing_zeroes, useful_digits;
  int padding, unpadded_width;
  char *p;
  char *exponent_start;
  register int i;
#define EBUF_SIZE 12
#define EBUF_END &ebuf[EBUF_SIZE]
  char ebuf[EBUF_SIZE];
  char *end;
  int exp = 0;
  switch (type)
    {
    case 'f':
      mode = 3;
      break;
    case 'e':
    case 'E':
      exp = type;
      mode = 2;
      if (precision != 999)
	precision++;  /* Add one to include digit before decimal point. */
      break;
    case 'g':
    case 'G':
      exp = type == 'g' ? 'e' : 'E';
      if (precision == 0) precision = 1;
      if (!(flags & _IO_SHOWPOINT))
	skip_zeroes = 1;
      type = 'g';
      mode = 2;
      break;
    }
  /* Do the actual convension */
  if (precision == 999 && mode != 3)
    mode = 0;
  p = _IO_dtoa(value, mode, precision, &decpt, &sign, &end);
  useful_digits = end-p;
  exponent_start = EBUF_END;
  if (mode == 0)
    precision = useful_digits;
  /* Check if we need to emit an exponent. */
  if (mode != 3 && decpt != 9999)
    {
      i = decpt - 1;
      if ((type != 'g' && type != 'F') || i < -4 || i >= precision)
	{
	  /* Print the exponent into ebuf.
	     We write ebuf in reverse order (right-to-left). */
	  char sign;
	  if (i >= 0)
	    sign = '+';
	  else
	    sign = '-', i = -i;
	  /* Note: ANSI requires at least 2 exponent digits. */
	  do {
	    *--exponent_start = (i % 10) + '0';
	    i /= 10;
	  } while (i >= 10);
	  *--exponent_start = i + '0';
	  *--exponent_start = sign;
	  *--exponent_start = exp;
	}
    }
  exponent_size = EBUF_END - exponent_start;
  if (mode == 1)
    precision = 1;
  /* If we print an exponent, always show just one digit before point. */
  if (exponent_size)
    decpt = 1;
  if (decpt == 9999)
    { /* Infinity or NaN */
      decpt = useful_digits;
      precision = 0;
      show_dot = 0;
    }
  
  /* dtoa truncates trailing zeroes.  Set the variable trailing_zeroes to
     the number of 0's we have to add (after the decimal point). */
  if (skip_zeroes)
    trailing_zeroes = 0;
  else if (type == 'f')
    trailing_zeroes = useful_digits <= decpt ? precision
      : precision-(useful_digits-decpt);
  else if (exponent_size) /* 'e' 'E' or 'g' format using exponential notation*/
    trailing_zeroes = precision - useful_digits;
  else /* 'g' format not using exponential notation. */
    trailing_zeroes = useful_digits <= decpt ? precision - decpt
      : precision-useful_digits;
  if (trailing_zeroes < 0) trailing_zeroes = 0;
  
  if (trailing_zeroes != 0 || useful_digits > decpt)
    show_dot = 1;
  if (sign_mode == 0)
    print_sign = sign ? '-' : 0;
  else if (sign_mode == '+')
    print_sign = sign ? '-' : '+';
  else /* if (sign_mode == ' ') */
    print_sign = sign ? '-' : ' ';
  
  /* Calculate the width (before padding). */
  unpadded_width =
    (print_sign != 0) + trailing_zeroes + exponent_size + show_dot
      + useful_digits
	+ (decpt > useful_digits ? decpt - useful_digits
	   : decpt > 0 ? 0 : 1 - decpt);
  
  padding = width > unpadded_width ? width - unpadded_width : 0;
  if (padding > 0 && pad_kind != _IO_LEFT && pad_kind != _IO_INTERNAL)
    PADN(fill, padding); /* Default (right) adjust */
  if (print_sign)
    PUT(print_sign);
  if (pad_kind == _IO_INTERNAL && padding > 0)
    PADN(fill, padding);
  if (decpt > 0)
    {
      if (useful_digits >= decpt)
	PUTN(p, decpt);
      else
	{
	  PUTN(p, useful_digits);
	  PADN('0', decpt-useful_digits);
	}
      if (show_dot)
	{
	  PUT('.');
	  /* Print digits after the decimal point. */
	  if (useful_digits > decpt)
	    PUTN(p + decpt, useful_digits-decpt);
	}
    }
  else
    {
      PUT('0');
      if (show_dot)
	{
	  PUT('.');
	  PADN('0', -decpt);
	  /* Print digits after the decimal point. */
	  PUTN(p, useful_digits);
	}
    }
  PADN('0', trailing_zeroes);
  if (exponent_size)
    PUTN(exponent_start, exponent_size);
  if (pad_kind == _IO_LEFT && padding > 0) /* Left adjustment*/
    PADN(fill, padding);
  return count;
 error:
  return EOF;
}
#endif