stdio-common/printf_fphex.c

   1 /* Print floating point number in hexadecimal notation according to ISO C99.
   2    Copyright (C) 1997-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <ctype.h>
  21 #include <ieee754.h>
  22 #include <math.h>
  23 #include <printf.h>
  24 #include <stdlib.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <wchar.h>
  28 #include <_itoa.h>
  29 #include <_itowa.h>
  30 #include <locale/localeinfo.h>
  31 #include <stdbool.h>
  32 #include <rounding-mode.h>
  33
  34 /* #define NDEBUG 1*/           /* Undefine this for debugging assertions.  */
  35 #include <assert.h>
  36
  37 /* This defines make it possible to use the same code for GNU C library and
  38    the GNU I/O library.  */
  39 #include <libioP.h>
  40 #define PUT(f, s, n) _IO_sputn (f, s, n)
  41 #define PAD(f, c, n) (wide ? _IO_wpadn (f, c, n) : _IO_padn (f, c, n))
  42 /* We use this file GNU C library and GNU I/O library.  So make
  43    names equal.  */
  44 #undef putc
  45 #define putc(c, f) (wide \
  46                      ? (int)_IO_putwc_unlocked (c, f) : _IO_putc_unlocked (c, f))
  47 #define size_t     _IO_size_t
  48 #define FILE         _IO_FILE
  49 \f
  50 /* Macros for doing the actual output.  */
  51
  52 #define outchar(ch)                                                           \
  53   do                                                                          \
  54     {                                                                         \
  55       const int outc = (ch);                                                  \
  56       if (putc (outc, fp) == EOF)                                             \
  57         return -1;                                                            \
  58       ++done;                                                                 \
  59     } while (0)
  60
  61 #define PRINT(ptr, wptr, len)                                                 \
  62   do                                                                          \
  63     {                                                                         \
  64       size_t outlen = (len);                                                  \
  65       if (wide)                                                               \
  66         while (outlen-- > 0)                                                  \
  67           outchar (*wptr++);                                                  \
  68       else                                                                    \
  69         while (outlen-- > 0)                                                  \
  70           outchar (*ptr++);                                                   \
  71     } while (0)
  72
  73 #define PADN(ch, len)                                                         \
  74   do                                                                          \
  75     {                                                                         \
  76       if (PAD (fp, ch, len) != len)                                           \
  77         return -1;                                                            \
  78       done += len;                                                            \
  79     }                                                                         \
  80   while (0)
  81
  82 #ifndef MIN
  83 # define MIN(a,b) ((a)<(b)?(a):(b))
  84 #endif
  85 \f
  86
  87 int
  88 __printf_fphex (FILE *fp,
  89                 const struct printf_info *info,
  90                 const void *const *args)
  91 {
  92   /* The floating-point value to output.  */
  93   union
  94     {
  95       union ieee754_double dbl;
  96       long double ldbl;
  97     }
  98   fpnum;
  99
 100   /* Locale-dependent representation of decimal point.  */
 101   const char *decimal;
 102   wchar_t decimalwc;
 103
 104   /* "NaN" or "Inf" for the special cases.  */
 105   const char *special = NULL;
 106   const wchar_t *wspecial = NULL;
 107
 108   /* Buffer for the generated number string for the mantissa.  The
 109      maximal size for the mantissa is 128 bits.  */
 110   char numbuf[32];
 111   char *numstr;
 112   char *numend;
 113   wchar_t wnumbuf[32];
 114   wchar_t *wnumstr;
 115   wchar_t *wnumend;
 116   int negative;
 117
 118   /* The maximal exponent of two in decimal notation has 5 digits.  */
 119   char expbuf[5];
 120   char *expstr;
 121   wchar_t wexpbuf[5];
 122   wchar_t *wexpstr;
 123   int expnegative;
 124   int exponent;
 125
 126   /* Non-zero is mantissa is zero.  */
 127   int zero_mantissa;
 128
 129   /* The leading digit before the decimal point.  */
 130   char leading;
 131
 132   /* Precision.  */
 133   int precision = info->prec;
 134
 135   /* Width.  */
 136   int width = info->width;
 137
 138   /* Number of characters written.  */
 139   int done = 0;
 140
 141   /* Nonzero if this is output on a wide character stream.  */
 142   int wide = info->wide;
 143
 144
 145   /* Figure out the decimal point character.  */
 146   if (info->extra == 0)
 147     {
 148       decimal = _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
 149       decimalwc = _NL_CURRENT_WORD (LC_NUMERIC, _NL_NUMERIC_DECIMAL_POINT_WC);
 150     }
 151   else
 152     {
 153       decimal = _NL_CURRENT (LC_MONETARY, MON_DECIMAL_POINT);
 154       decimalwc = _NL_CURRENT_WORD (LC_MONETARY,
 155                                     _NL_MONETARY_DECIMAL_POINT_WC);
 156     }
 157   /* The decimal point character must never be zero.  */
 158   assert (*decimal != '\0' && decimalwc != L'\0');
 159
 160
 161   /* Fetch the argument value.  */
 162 #ifndef __NO_LONG_DOUBLE_MATH
 163   if (info->is_long_double && sizeof (long double) > sizeof (double))
 164     {
 165       fpnum.ldbl = *(const long double *) args[0];
 166
 167       /* Check for special values: not a number or infinity.  */
 168       if (isnan (fpnum.ldbl))
 169         {
 170           if (isupper (info->spec))
 171             {
 172               special = "NAN";
 173               wspecial = L"NAN";
 174             }
 175           else
 176             {
 177               special = "nan";
 178               wspecial = L"nan";
 179             }
 180         }
 181       else
 182         {
 183           if (isinf (fpnum.ldbl))
 184             {
 185               if (isupper (info->spec))
 186                 {
 187                   special = "INF";
 188                   wspecial = L"INF";
 189                 }
 190               else
 191                 {
 192                   special = "inf";
 193                   wspecial = L"inf";
 194                 }
 195             }
 196         }
 197       negative = signbit (fpnum.ldbl);
 198     }
 199   else
 200 #endif  /* no long double */
 201     {
 202       fpnum.dbl.d = *(const double *) args[0];
 203
 204       /* Check for special values: not a number or infinity.  */
 205       if (isnan (fpnum.dbl.d))
 206         {
 207           if (isupper (info->spec))
 208             {
 209               special = "NAN";
 210               wspecial = L"NAN";
 211             }
 212           else
 213             {
 214               special = "nan";
 215               wspecial = L"nan";
 216             }
 217         }
 218       else
 219         {
 220           if (isinf (fpnum.dbl.d))
 221             {
 222               if (isupper (info->spec))
 223                 {
 224                   special = "INF";
 225                   wspecial = L"INF";
 226                 }
 227               else
 228                 {
 229                   special = "inf";
 230                   wspecial = L"inf";
 231                 }
 232             }
 233         }
 234       negative = signbit (fpnum.dbl.d);
 235     }
 236
 237   if (special)
 238     {
 239       int width = info->width;
 240
 241       if (negative || info->showsign || info->space)
 242         --width;
 243       width -= 3;
 244
 245       if (!info->left && width > 0)
 246         PADN (' ', width);
 247
 248       if (negative)
 249         outchar ('-');
 250       else if (info->showsign)
 251         outchar ('+');
 252       else if (info->space)
 253         outchar (' ');
 254
 255       PRINT (special, wspecial, 3);
 256
 257       if (info->left && width > 0)
 258         PADN (' ', width);
 259
 260       return done;
 261     }
 262
 263   if (info->is_long_double == 0 || sizeof (double) == sizeof (long double))
 264     {
 265       /* We have 52 bits of mantissa plus one implicit digit.  Since
 266          52 bits are representable without rest using hexadecimal
 267          digits we use only the implicit digits for the number before
 268          the decimal point.  */
 269       unsigned long long int num;
 270
 271       num = (((unsigned long long int) fpnum.dbl.ieee.mantissa0) << 32
 272              | fpnum.dbl.ieee.mantissa1);
 273
 274       zero_mantissa = num == 0;
 275
 276       if (sizeof (unsigned long int) > 6)
 277         {
 278           wnumstr = _itowa_word (num, wnumbuf + (sizeof wnumbuf) / sizeof (wchar_t), 16,
 279                                  info->spec == 'A');
 280           numstr = _itoa_word (num, numbuf + sizeof numbuf, 16,
 281                                info->spec == 'A');
 282         }
 283       else
 284         {
 285           wnumstr = _itowa (num, wnumbuf + sizeof wnumbuf / sizeof (wchar_t), 16,
 286                             info->spec == 'A');
 287           numstr = _itoa (num, numbuf + sizeof numbuf, 16,
 288                           info->spec == 'A');
 289         }
 290
 291       /* Fill with zeroes.  */
 292       while (wnumstr > wnumbuf + (sizeof wnumbuf - 52) / sizeof (wchar_t))
 293         {
 294           *--wnumstr = L'0';
 295           *--numstr = '0';
 296         }
 297
 298       leading = fpnum.dbl.ieee.exponent == 0 ? '0' : '1';
 299
 300       exponent = fpnum.dbl.ieee.exponent;
 301
 302       if (exponent == 0)
 303         {
 304           if (zero_mantissa)
 305             expnegative = 0;
 306           else
 307             {
 308               /* This is a denormalized number.  */
 309               expnegative = 1;
 310               exponent = IEEE754_DOUBLE_BIAS - 1;
 311             }
 312         }
 313       else if (exponent >= IEEE754_DOUBLE_BIAS)
 314         {
 315           expnegative = 0;
 316           exponent -= IEEE754_DOUBLE_BIAS;
 317         }
 318       else
 319         {
 320           expnegative = 1;
 321           exponent = -(exponent - IEEE754_DOUBLE_BIAS);
 322         }
 323     }
 324 #ifdef PRINT_FPHEX_LONG_DOUBLE
 325   else
 326     PRINT_FPHEX_LONG_DOUBLE;
 327 #endif
 328
 329   /* Look for trailing zeroes.  */
 330   if (! zero_mantissa)
 331     {
 332       wnumend = &wnumbuf[sizeof wnumbuf / sizeof wnumbuf[0]];
 333       numend = &numbuf[sizeof numbuf / sizeof numbuf[0]];
 334       while (wnumend[-1] == L'0')
 335         {
 336           --wnumend;
 337           --numend;
 338         }
 339
 340       bool do_round_away = false;
 341
 342       if (precision != -1 && precision < numend - numstr)
 343         {
 344           char last_digit = precision > 0 ? numstr[precision - 1] : leading;
 345           char next_digit = numstr[precision];
 346           int last_digit_value = (last_digit >= 'A' && last_digit <= 'F'
 347                                   ? last_digit - 'A' + 10
 348                                   : (last_digit >= 'a' && last_digit <= 'f'
 349                                      ? last_digit - 'a' + 10
 350                                      : last_digit - '0'));
 351           int next_digit_value = (next_digit >= 'A' && next_digit <= 'F'
 352                                   ? next_digit - 'A' + 10
 353                                   : (next_digit >= 'a' && next_digit <= 'f'
 354                                      ? next_digit - 'a' + 10
 355                                      : next_digit - '0'));
 356           bool more_bits = ((next_digit_value & 7) != 0
 357                             || precision + 1 < numend - numstr);
 358           int rounding_mode = get_rounding_mode ();
 359           do_round_away = round_away (negative, last_digit_value & 1,
 360                                       next_digit_value >= 8, more_bits,
 361                                       rounding_mode);
 362         }
 363
 364       if (precision == -1)
 365         precision = numend - numstr;
 366       else if (do_round_away)
 367         {
 368           /* Round up.  */
 369           int cnt = precision;
 370           while (--cnt >= 0)
 371             {
 372               char ch = numstr[cnt];
 373               /* We assume that the digits and the letters are ordered
 374                  like in ASCII.  This is true for the rest of GNU, too.  */
 375               if (ch == '9')
 376                 {
 377                   wnumstr[cnt] = (wchar_t) info->spec;
 378                   numstr[cnt] = info->spec;     /* This is tricky,
 379                                                    think about it!  */
 380                   break;
 381                 }
 382               else if (tolower (ch) < 'f')
 383                 {
 384                   ++numstr[cnt];
 385                   ++wnumstr[cnt];
 386                   break;
 387                 }
 388               else
 389                 {
 390                   numstr[cnt] = '0';
 391                   wnumstr[cnt] = L'0';
 392                 }
 393             }
 394           if (cnt < 0)
 395             {
 396               /* The mantissa so far was fff...f  Now increment the
 397                  leading digit.  Here it is again possible that we
 398                  get an overflow.  */
 399               if (leading == '9')
 400                 leading = info->spec;
 401               else if (tolower (leading) < 'f')
 402                 ++leading;
 403               else
 404                 {
 405                   leading = '1';
 406                   if (expnegative)
 407                     {
 408                       exponent -= 4;
 409                       if (exponent <= 0)
 410                         {
 411                           exponent = -exponent;
 412                           expnegative = 0;
 413                         }
 414                     }
 415                   else
 416                     exponent += 4;
 417                 }
 418             }
 419         }
 420     }
 421   else
 422     {
 423       if (precision == -1)
 424         precision = 0;
 425       numend = numstr;
 426       wnumend = wnumstr;
 427     }
 428
 429   /* Now we can compute the exponent string.  */
 430   expstr = _itoa_word (exponent, expbuf + sizeof expbuf, 10, 0);
 431   wexpstr = _itowa_word (exponent,
 432                          wexpbuf + sizeof wexpbuf / sizeof (wchar_t), 10, 0);
 433
 434   /* Now we have all information to compute the size.  */
 435   width -= ((negative || info->showsign || info->space)
 436             /* Sign.  */
 437             + 2    + 1 + 0 + precision + 1 + 1
 438             /* 0x    h   .   hhh         P   ExpoSign.  */
 439             + ((expbuf + sizeof expbuf) - expstr));
 440             /* Exponent.  */
 441
 442   /* Count the decimal point.
 443      A special case when the mantissa or the precision is zero and the `#'
 444      is not given.  In this case we must not print the decimal point.  */
 445   if (precision > 0 || info->alt)
 446     width -= wide ? 1 : strlen (decimal);
 447
 448   if (!info->left && info->pad != '0' && width > 0)
 449     PADN (' ', width);
 450
 451   if (negative)
 452     outchar ('-');
 453   else if (info->showsign)
 454     outchar ('+');
 455   else if (info->space)
 456     outchar (' ');
 457
 458   outchar ('0');
 459   if ('X' - 'A' == 'x' - 'a')
 460     outchar (info->spec + ('x' - 'a'));
 461   else
 462     outchar (info->spec == 'A' ? 'X' : 'x');
 463
 464   if (!info->left && info->pad == '0' && width > 0)
 465     PADN ('0', width);
 466
 467   outchar (leading);
 468
 469   if (precision > 0 || info->alt)
 470     {
 471       const wchar_t *wtmp = &decimalwc;
 472       PRINT (decimal, wtmp, wide ? 1 : strlen (decimal));
 473     }
 474
 475   if (precision > 0)
 476     {
 477       ssize_t tofill = precision - (numend - numstr);
 478       PRINT (numstr, wnumstr, MIN (numend - numstr, precision));
 479       if (tofill > 0)
 480         PADN ('0', tofill);
 481     }
 482
 483   if ('P' - 'A' == 'p' - 'a')
 484     outchar (info->spec + ('p' - 'a'));
 485   else
 486     outchar (info->spec == 'A' ? 'P' : 'p');
 487
 488   outchar (expnegative ? '-' : '+');
 489
 490   PRINT (expstr, wexpstr, (expbuf + sizeof expbuf) - expstr);
 491
 492   if (info->left && info->pad != '0' && width > 0)
 493     PADN (info->pad, width);
 494
 495   return done;
 496 }