stdio-common/printf_fphex.c

   1 /* Print floating point number in hexadecimal notation according to ISO C99.
   2    Copyright (C) 1997-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <array_length.h>
  20 #include <assert.h>
  21 #include <ctype.h>
  22 #include <ieee754.h>
  23 #include <math.h>
  24 #include <printf.h>
  25 #include <libioP.h>
  26 #include <stdlib.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #include <wchar.h>
  30 #include <_itoa.h>
  31 #include <_itowa.h>
  32 #include <locale/localeinfo.h>
  33 #include <stdbool.h>
  34 #include <rounding-mode.h>
  35 #include <sys/param.h>
  36 #include <printf_buffer.h>
  37 #include <errno.h>
  38
  39 #if __HAVE_DISTINCT_FLOAT128
  40 # include "ieee754_float128.h"
  41 # include <ldbl-128/printf_fphex_macros.h>
  42 # define PRINT_FPHEX_FLOAT128 \
  43    PRINT_FPHEX (_Float128, fpnum.flt128, ieee854_float128, \
  44                 IEEE854_FLOAT128_BIAS)
  45 #endif
  46
  47 static void
  48 __printf_fphex_buffer (struct __printf_buffer *buf,
  49                        const char *decimal,
  50                        const struct printf_info *info,
  51                        const void *const *args)
  52 {
  53   /* The floating-point value to output.  */
  54   union
  55     {
  56       union ieee754_double dbl;
  57       long double ldbl;
  58 #if __HAVE_DISTINCT_FLOAT128
  59       _Float128 flt128;
  60 #endif
  61     }
  62   fpnum;
  63
  64   /* This function always uses LC_NUMERIC.  */
  65   assert (info->extra == 0);
  66
  67   /* "NaN" or "Inf" for the special cases.  */
  68   const char *special = NULL;
  69
  70   /* Buffer for the generated number string for the mantissa.  The
  71      maximal size for the mantissa is 128 bits.  */
  72   char numbuf[32];
  73   char *numstr;
  74   char *numend;
  75   int negative;
  76
  77   /* The maximal exponent of two in decimal notation has 5 digits.  */
  78   char expbuf[5];
  79   char *expstr;
  80   int expnegative;
  81   int exponent;
  82
  83   /* Non-zero is mantissa is zero.  */
  84   int zero_mantissa;
  85
  86   /* The leading digit before the decimal point.  */
  87   char leading;
  88
  89   /* Precision.  */
  90   int precision = info->prec;
  91
  92   /* Width.  */
  93   int width = info->width;
  94
  95 #define PRINTF_FPHEX_FETCH(FLOAT, VAR)                                  \
  96   {                                                                     \
  97     (VAR) = *(const FLOAT *) args[0];                                   \
  98                                                                         \
  99     /* Check for special values: not a number or infinity.  */          \
 100     if (isnan (VAR))                                                    \
 101       {                                                                 \
 102         if (isupper (info->spec))                                       \
 103           special = "NAN";                                              \
 104         else                                                            \
 105           special = "nan";                                              \
 106       }                                                                 \
 107     else                                                                \
 108       {                                                                 \
 109         if (isinf (VAR))                                                \
 110           {                                                             \
 111             if (isupper (info->spec))                                   \
 112               special = "INF";                                          \
 113             else                                                        \
 114               special = "inf";                                          \
 115           }                                                             \
 116       }                                                                 \
 117     negative = signbit (VAR);                                           \
 118   }
 119
 120   /* Fetch the argument value.  */
 121 #if __HAVE_DISTINCT_FLOAT128
 122   if (info->is_binary128)
 123     PRINTF_FPHEX_FETCH (_Float128, fpnum.flt128)
 124   else
 125 #endif
 126 #ifndef __NO_LONG_DOUBLE_MATH
 127   if (info->is_long_double && sizeof (long double) > sizeof (double))
 128     PRINTF_FPHEX_FETCH (long double, fpnum.ldbl)
 129   else
 130 #endif
 131     PRINTF_FPHEX_FETCH (double, fpnum.dbl.d)
 132
 133 #undef PRINTF_FPHEX_FETCH
 134
 135   if (special)
 136     {
 137       int width = info->width;
 138
 139       if (negative || info->showsign || info->space)
 140         --width;
 141       width -= 3;
 142
 143       if (!info->left)
 144         __printf_buffer_pad (buf, ' ', width);
 145
 146       if (negative)
 147         __printf_buffer_putc (buf, '-');
 148       else if (info->showsign)
 149         __printf_buffer_putc (buf, '+');
 150       else if (info->space)
 151         __printf_buffer_putc (buf, ' ');
 152
 153       __printf_buffer_puts (buf, special);
 154
 155       if (info->left)
 156         __printf_buffer_pad (buf, ' ', width);
 157
 158       return;
 159     }
 160
 161 #if __HAVE_DISTINCT_FLOAT128
 162   if (info->is_binary128)
 163     PRINT_FPHEX_FLOAT128;
 164   else
 165 #endif
 166   if (info->is_long_double == 0 || sizeof (double) == sizeof (long double))
 167     {
 168       /* We have 52 bits of mantissa plus one implicit digit.  Since
 169          52 bits are representable without rest using hexadecimal
 170          digits we use only the implicit digits for the number before
 171          the decimal point.  */
 172       unsigned long long int num;
 173
 174       num = (((unsigned long long int) fpnum.dbl.ieee.mantissa0) << 32
 175              | fpnum.dbl.ieee.mantissa1);
 176
 177       zero_mantissa = num == 0;
 178
 179       if (sizeof (unsigned long int) > 6)
 180           numstr = _itoa_word (num, numbuf + sizeof numbuf, 16,
 181                                info->spec == 'A');
 182       else
 183           numstr = _itoa (num, numbuf + sizeof numbuf, 16,
 184                           info->spec == 'A');
 185
 186       /* Fill with zeroes.  */
 187       while (numstr > numbuf + (sizeof numbuf - 13))
 188         *--numstr = '0';
 189
 190       leading = fpnum.dbl.ieee.exponent == 0 ? '0' : '1';
 191
 192       exponent = fpnum.dbl.ieee.exponent;
 193
 194       if (exponent == 0)
 195         {
 196           if (zero_mantissa)
 197             expnegative = 0;
 198           else
 199             {
 200               /* This is a denormalized number.  */
 201               expnegative = 1;
 202               exponent = IEEE754_DOUBLE_BIAS - 1;
 203             }
 204         }
 205       else if (exponent >= IEEE754_DOUBLE_BIAS)
 206         {
 207           expnegative = 0;
 208           exponent -= IEEE754_DOUBLE_BIAS;
 209         }
 210       else
 211         {
 212           expnegative = 1;
 213           exponent = -(exponent - IEEE754_DOUBLE_BIAS);
 214         }
 215     }
 216 #ifdef PRINT_FPHEX_LONG_DOUBLE
 217   else
 218     PRINT_FPHEX_LONG_DOUBLE;
 219 #endif
 220
 221   /* Look for trailing zeroes.  */
 222   if (! zero_mantissa)
 223     {
 224       numend = array_end (numbuf);
 225       while (numend[-1] == '0')
 226           --numend;
 227
 228       bool do_round_away = false;
 229
 230       if (precision != -1 && precision < numend - numstr)
 231         {
 232           char last_digit = precision > 0 ? numstr[precision - 1] : leading;
 233           char next_digit = numstr[precision];
 234           int last_digit_value = (last_digit >= 'A' && last_digit <= 'F'
 235                                   ? last_digit - 'A' + 10
 236                                   : (last_digit >= 'a' && last_digit <= 'f'
 237                                      ? last_digit - 'a' + 10
 238                                      : last_digit - '0'));
 239           int next_digit_value = (next_digit >= 'A' && next_digit <= 'F'
 240                                   ? next_digit - 'A' + 10
 241                                   : (next_digit >= 'a' && next_digit <= 'f'
 242                                      ? next_digit - 'a' + 10
 243                                      : next_digit - '0'));
 244           bool more_bits = ((next_digit_value & 7) != 0
 245                             || precision + 1 < numend - numstr);
 246           int rounding_mode = get_rounding_mode ();
 247           do_round_away = round_away (negative, last_digit_value & 1,
 248                                       next_digit_value >= 8, more_bits,
 249                                       rounding_mode);
 250         }
 251
 252       if (precision == -1)
 253         precision = numend - numstr;
 254       else if (do_round_away)
 255         {
 256           /* Round up.  */
 257           int cnt = precision;
 258           while (--cnt >= 0)
 259             {
 260               char ch = numstr[cnt];
 261               /* We assume that the digits and the letters are ordered
 262                  like in ASCII.  This is true for the rest of GNU, too.  */
 263               if (ch == '9')
 264                 {
 265                   numstr[cnt] = info->spec;     /* This is tricky,
 266                                                    think about it!  */
 267                   break;
 268                 }
 269               else if (tolower (ch) < 'f')
 270                 {
 271                   ++numstr[cnt];
 272                   break;
 273                 }
 274               else
 275                 numstr[cnt] = '0';
 276             }
 277           if (cnt < 0)
 278             {
 279               /* The mantissa so far was fff...f  Now increment the
 280                  leading digit.  Here it is again possible that we
 281                  get an overflow.  */
 282               if (leading == '9')
 283                 leading = info->spec;
 284               else if (tolower (leading) < 'f')
 285                 ++leading;
 286               else
 287                 {
 288                   leading = '1';
 289                   if (expnegative)
 290                     {
 291                       exponent -= 4;
 292                       if (exponent <= 0)
 293                         {
 294                           exponent = -exponent;
 295                           expnegative = 0;
 296                         }
 297                     }
 298                   else
 299                     exponent += 4;
 300                 }
 301             }
 302         }
 303     }
 304   else
 305     {
 306       if (precision == -1)
 307         precision = 0;
 308       numend = numstr;
 309     }
 310
 311   /* Now we can compute the exponent string.  */
 312   expstr = _itoa_word (exponent, expbuf + sizeof expbuf, 10, 0);
 313
 314   /* Now we have all information to compute the size.  */
 315   width -= ((negative || info->showsign || info->space)
 316             /* Sign.  */
 317             + 2    + 1 + 0 + precision + 1 + 1
 318             /* 0x    h   .   hhh         P   ExpoSign.  */
 319             + ((expbuf + sizeof expbuf) - expstr));
 320             /* Exponent.  */
 321
 322   /* Count the decimal point.
 323      A special case when the mantissa or the precision is zero and the `#'
 324      is not given.  In this case we must not print the decimal point.  */
 325   if (precision > 0 || info->alt)
 326     --width;
 327
 328   if (!info->left && info->pad != '0')
 329     __printf_buffer_pad (buf, ' ', width);
 330
 331   if (negative)
 332     __printf_buffer_putc (buf, '-');
 333   else if (info->showsign)
 334     __printf_buffer_putc (buf, '+');
 335   else if (info->space)
 336     __printf_buffer_putc (buf, ' ');
 337
 338   __printf_buffer_putc (buf, '0');
 339   if ('X' - 'A' == 'x' - 'a')
 340     __printf_buffer_putc (buf, info->spec + ('x' - 'a'));
 341   else
 342     __printf_buffer_putc (buf, info->spec == 'A' ? 'X' : 'x');
 343
 344   if (!info->left && info->pad == '0')
 345     __printf_buffer_pad (buf, '0', width);
 346
 347   __printf_buffer_putc (buf, leading);
 348
 349   if (precision > 0 || info->alt)
 350     __printf_buffer_puts (buf, decimal);
 351
 352   if (precision > 0)
 353     {
 354       ssize_t tofill = precision - (numend - numstr);
 355       __printf_buffer_write (buf, numstr, MIN (numend - numstr, precision));
 356       __printf_buffer_pad (buf, '0', tofill);
 357     }
 358
 359   if ('P' - 'A' == 'p' - 'a')
 360     __printf_buffer_putc (buf, info->spec + ('p' - 'a'));
 361   else
 362     __printf_buffer_putc (buf, info->spec == 'A' ? 'P' : 'p');
 363
 364   __printf_buffer_putc (buf, expnegative ? '-' : '+');
 365
 366   __printf_buffer_write (buf, expstr, (expbuf + sizeof expbuf) - expstr);
 367
 368   if (info->left && info->pad != '0')
 369     __printf_buffer_pad (buf, info->pad, width);
 370 }
 371
 372 void
 373 __printf_fphex_l_buffer (struct __printf_buffer *buf, locale_t loc,
 374                          const struct printf_info *info,
 375                          const void *const *args)
 376 {
 377   __printf_fphex_buffer (buf, _nl_lookup (loc, LC_NUMERIC, DECIMAL_POINT),
 378                          info, args);
 379 }
 380
 381
 382 /* The wide buffer version is implemented by translating the output of
 383    the multibyte version.  */
 384
 385 struct __printf_buffer_fphex_to_wide
 386 {
 387   struct __printf_buffer base;
 388   wchar_t decimalwc;
 389   struct __wprintf_buffer *next;
 390   char untranslated[PRINTF_BUFFER_SIZE_DIGITS];
 391 };
 392
 393 /* Translate to wide characters, rewriting "." to the actual decimal
 394    point.  */
 395 void
 396 __printf_buffer_flush_fphex_to_wide (struct __printf_buffer_fphex_to_wide *buf)
 397 {
 398   /* No need to adjust buf->base.written, only buf->next->written matters.  */
 399   for (char *p = buf->untranslated; p < buf->base.write_ptr; ++p)
 400     {
 401       /* wchar_t overlaps with char in the ASCII range.  */
 402       wchar_t ch = *p;
 403       if (ch == L'.')
 404         ch = buf->decimalwc;
 405       __wprintf_buffer_putc (buf->next, ch);
 406     }
 407
 408   if (!__wprintf_buffer_has_failed (buf->next))
 409     buf->base.write_ptr = buf->untranslated;
 410   else
 411     __printf_buffer_mark_failed (&buf->base);
 412 }
 413
 414 void
 415 __wprintf_fphex_l_buffer (struct __wprintf_buffer *next, locale_t loc,
 416                           const struct printf_info *info,
 417                           const void *const *args)
 418 {
 419   struct __printf_buffer_fphex_to_wide buf;
 420   __printf_buffer_init (&buf.base, buf.untranslated, sizeof (buf.untranslated),
 421                         __printf_buffer_mode_fphex_to_wide);
 422   buf.decimalwc = _nl_lookup_word (loc, LC_NUMERIC,
 423                                    _NL_NUMERIC_DECIMAL_POINT_WC);
 424   buf.next = next;
 425   __printf_fphex_buffer (&buf.base, ".", info, args);
 426   if (__printf_buffer_has_failed (&buf.base))
 427     {
 428       __wprintf_buffer_mark_failed (buf.next);
 429       return;
 430     }
 431   __printf_buffer_flush_fphex_to_wide (&buf);
 432 }