stdio-common/_itowa.c

   1 /* Internal function for converting integers to ASCII.
   2    Copyright (C) 1994-2022 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 <gmp-mparam.h>
  20 #include <gmp.h>
  21 #include <limits.h>
  22 #include <stdlib/gmp-impl.h>
  23 #include <stdlib/longlong.h>
  24
  25 #include <_itowa.h>
  26
  27
  28 /* Canonize environment.  For some architectures not all values might
  29    be defined in the GMP header files.  */
  30 #ifndef UMUL_TIME
  31 # define UMUL_TIME 1
  32 #endif
  33 #ifndef UDIV_TIME
  34 # define UDIV_TIME 3
  35 #endif
  36
  37 /* Control memory layout.  */
  38 #ifdef PACK
  39 # undef PACK
  40 # define PACK __attribute__ ((packed))
  41 #else
  42 # define PACK
  43 #endif
  44
  45
  46 /* Declare local types.  */
  47 struct base_table_t
  48 {
  49 #if (UDIV_TIME > 2 * UMUL_TIME)
  50   mp_limb_t base_multiplier;
  51 #endif
  52   char flag;
  53   char post_shift;
  54 #if BITS_PER_MP_LIMB == 32
  55   struct
  56     {
  57       char normalization_steps;
  58       char ndigits;
  59       mp_limb_t base PACK;
  60 #if UDIV_TIME > 2 * UMUL_TIME
  61       mp_limb_t base_ninv PACK;
  62 #endif
  63     } big;
  64 #endif
  65 };
  66
  67 /* To reduce the memory needed we include some fields of the tables
  68    only conditionally.  */
  69 #if UDIV_TIME > 2 * UMUL_TIME
  70 # define SEL1(X) X,
  71 # define SEL2(X) ,X
  72 #else
  73 # define SEL1(X)
  74 # define SEL2(X)
  75 #endif
  76
  77 /* Factor table for the different bases.  */
  78 extern const struct base_table_t _itoa_base_table[] attribute_hidden;
  79
  80 /* Lower-case digits.  */
  81 extern const wchar_t _itowa_lower_digits[] attribute_hidden;
  82 /* Upper-case digits.  */
  83 extern const wchar_t _itowa_upper_digits[] attribute_hidden;
  84
  85
  86 #if _ITOA_NEEDED
  87 wchar_t *
  88 _itowa (unsigned long long int value, wchar_t *buflim, unsigned int base,
  89         int upper_case)
  90 {
  91   const wchar_t *digits = (upper_case
  92                            ? _itowa_upper_digits : _itowa_lower_digits);
  93   wchar_t *bp = buflim;
  94   const struct base_table_t *brec = &_itoa_base_table[base - 2];
  95
  96   switch (base)
  97     {
  98 # define RUN_2N(BITS) \
  99       do                                                                      \
 100         {                                                                     \
 101           /* `unsigned long long int' always has 64 bits.  */                 \
 102           mp_limb_t work_hi = value >> (64 - BITS_PER_MP_LIMB);               \
 103                                                                               \
 104           if (BITS_PER_MP_LIMB == 32)                                         \
 105             {                                                                 \
 106               if (work_hi != 0)                                               \
 107                 {                                                             \
 108                   mp_limb_t work_lo;                                          \
 109                   int cnt;                                                    \
 110                                                                               \
 111                   work_lo = value & 0xfffffffful;                             \
 112                   for (cnt = BITS_PER_MP_LIMB / BITS; cnt > 0; --cnt)         \
 113                     {                                                         \
 114                       *--bp = digits[work_lo & ((1ul << BITS) - 1)];          \
 115                       work_lo >>= BITS;                                       \
 116                     }                                                         \
 117                   if (BITS_PER_MP_LIMB % BITS != 0)                           \
 118                     {                                                         \
 119                       work_lo                                                 \
 120                         |= ((work_hi                                          \
 121                              & ((1 << (BITS - BITS_PER_MP_LIMB%BITS))         \
 122                                 - 1))                                         \
 123                             << BITS_PER_MP_LIMB % BITS);                      \
 124                       work_hi >>= BITS - BITS_PER_MP_LIMB % BITS;             \
 125                       if (work_hi == 0)                                       \
 126                         work_hi = work_lo;                                    \
 127                       else                                                    \
 128                         *--bp = digits[work_lo];                              \
 129                     }                                                         \
 130                 }                                                             \
 131               else                                                            \
 132                 work_hi = value & 0xfffffffful;                               \
 133             }                                                                 \
 134           do                                                                  \
 135             {                                                                 \
 136               *--bp = digits[work_hi & ((1 << BITS) - 1)];                    \
 137               work_hi >>= BITS;                                               \
 138             }                                                                 \
 139           while (work_hi != 0);                                               \
 140         }                                                                     \
 141       while (0)
 142     case 8:
 143       RUN_2N (3);
 144       break;
 145
 146     case 16:
 147       RUN_2N (4);
 148       break;
 149
 150     default:
 151       {
 152 # if BITS_PER_MP_LIMB == 64
 153         mp_limb_t base_multiplier = brec->base_multiplier;
 154         if (brec->flag)
 155           while (value != 0)
 156             {
 157               mp_limb_t quo, rem, x;
 158               mp_limb_t dummy __attribute__ ((unused));
 159
 160               umul_ppmm (x, dummy, value, base_multiplier);
 161               quo = (x + ((value - x) >> 1)) >> (brec->post_shift - 1);
 162               rem = value - quo * base;
 163               *--bp = digits[rem];
 164               value = quo;
 165             }
 166         else
 167           while (value != 0)
 168             {
 169               mp_limb_t quo, rem, x;
 170               mp_limb_t dummy __attribute__ ((unused));
 171
 172               umul_ppmm (x, dummy, value, base_multiplier);
 173               quo = x >> brec->post_shift;
 174               rem = value - quo * base;
 175               *--bp = digits[rem];
 176               value = quo;
 177             }
 178 # endif
 179 # if BITS_PER_MP_LIMB == 32
 180         mp_limb_t t[3];
 181         int n;
 182
 183         /* First convert x0 to 1-3 words in base s->big.base.
 184            Optimize for frequent cases of 32 bit numbers.  */
 185         if ((mp_limb_t) (value >> 32) >= 1)
 186           {
 187 # if UDIV_TIME > 2 * UMUL_TIME || UDIV_NEEDS_NORMALIZATION
 188             int big_normalization_steps = brec->big.normalization_steps;
 189             mp_limb_t big_base_norm
 190               = brec->big.base << big_normalization_steps;
 191 # endif
 192             if ((mp_limb_t) (value >> 32) >= brec->big.base)
 193               {
 194                 mp_limb_t x1hi, x1lo, r;
 195                 /* If you want to optimize this, take advantage of
 196                    that the quotient in the first udiv_qrnnd will
 197                    always be very small.  It might be faster just to
 198                    subtract in a tight loop.  */
 199
 200 # if UDIV_TIME > 2 * UMUL_TIME
 201                 mp_limb_t x, xh, xl;
 202
 203                 if (big_normalization_steps == 0)
 204                   xh = 0;
 205                 else
 206                   xh = (mp_limb_t) (value >> (64 - big_normalization_steps));
 207                 xl = (mp_limb_t) (value >> (32 - big_normalization_steps));
 208                 udiv_qrnnd_preinv (x1hi, r, xh, xl, big_base_norm,
 209                                    brec->big.base_ninv);
 210
 211                 xl = ((mp_limb_t) value) << big_normalization_steps;
 212                 udiv_qrnnd_preinv (x1lo, x, r, xl, big_base_norm,
 213                                    brec->big.base_ninv);
 214                 t[2] = x >> big_normalization_steps;
 215
 216                 if (big_normalization_steps == 0)
 217                   xh = x1hi;
 218                 else
 219                   xh = ((x1hi << big_normalization_steps)
 220                         | (x1lo >> (32 - big_normalization_steps)));
 221                 xl = x1lo << big_normalization_steps;
 222                 udiv_qrnnd_preinv (t[0], x, xh, xl, big_base_norm,
 223                                    brec->big.base_ninv);
 224                 t[1] = x >> big_normalization_steps;
 225 # elif UDIV_NEEDS_NORMALIZATION
 226                 mp_limb_t x, xh, xl;
 227
 228                 if (big_normalization_steps == 0)
 229                   xh = 0;
 230                 else
 231                   xh = (mp_limb_t) (value >> 64 - big_normalization_steps);
 232                 xl = (mp_limb_t) (value >> 32 - big_normalization_steps);
 233                 udiv_qrnnd (x1hi, r, xh, xl, big_base_norm);
 234
 235                 xl = ((mp_limb_t) value) << big_normalization_steps;
 236                 udiv_qrnnd (x1lo, x, r, xl, big_base_norm);
 237                 t[2] = x >> big_normalization_steps;
 238
 239                 if (big_normalization_steps == 0)
 240                   xh = x1hi;
 241                 else
 242                   xh = ((x1hi << big_normalization_steps)
 243                         | (x1lo >> 32 - big_normalization_steps));
 244                 xl = x1lo << big_normalization_steps;
 245                 udiv_qrnnd (t[0], x, xh, xl, big_base_norm);
 246                 t[1] = x >> big_normalization_steps;
 247 # else
 248                 udiv_qrnnd (x1hi, r, 0, (mp_limb_t) (value >> 32),
 249                             brec->big.base);
 250                 udiv_qrnnd (x1lo, t[2], r, (mp_limb_t) value, brec->big.base);
 251                 udiv_qrnnd (t[0], t[1], x1hi, x1lo, brec->big.base);
 252 # endif
 253                 n = 3;
 254               }
 255             else
 256               {
 257 # if UDIV_TIME > 2 * UMUL_TIME
 258                 mp_limb_t x;
 259
 260                 value <<= brec->big.normalization_steps;
 261                 udiv_qrnnd_preinv (t[0], x, (mp_limb_t) (value >> 32),
 262                                    (mp_limb_t) value, big_base_norm,
 263                                    brec->big.base_ninv);
 264                 t[1] = x >> brec->big.normalization_steps;
 265 # elif UDIV_NEEDS_NORMALIZATION
 266                 mp_limb_t x;
 267
 268                 value <<= big_normalization_steps;
 269                 udiv_qrnnd (t[0], x, (mp_limb_t) (value >> 32),
 270                             (mp_limb_t) value, big_base_norm);
 271                 t[1] = x >> big_normalization_steps;
 272 # else
 273                 udiv_qrnnd (t[0], t[1], (mp_limb_t) (value >> 32),
 274                             (mp_limb_t) value, brec->big.base);
 275 # endif
 276                 n = 2;
 277               }
 278           }
 279         else
 280           {
 281             t[0] = value;
 282             n = 1;
 283           }
 284
 285         /* Convert the 1-3 words in t[], word by word, to ASCII.  */
 286         do
 287           {
 288             mp_limb_t ti = t[--n];
 289             int ndig_for_this_limb = 0;
 290
 291 # if UDIV_TIME > 2 * UMUL_TIME
 292             mp_limb_t base_multiplier = brec->base_multiplier;
 293             if (brec->flag)
 294               while (ti != 0)
 295                 {
 296                   mp_limb_t quo, rem, x;
 297                   mp_limb_t dummy __attribute__ ((unused));
 298
 299                   umul_ppmm (x, dummy, ti, base_multiplier);
 300                   quo = (x + ((ti - x) >> 1)) >> (brec->post_shift - 1);
 301                   rem = ti - quo * base;
 302                   *--bp = digits[rem];
 303                   ti = quo;
 304                   ++ndig_for_this_limb;
 305                 }
 306             else
 307               while (ti != 0)
 308                 {
 309                   mp_limb_t quo, rem, x;
 310                   mp_limb_t dummy __attribute__ ((unused));
 311
 312                   umul_ppmm (x, dummy, ti, base_multiplier);
 313                   quo = x >> brec->post_shift;
 314                   rem = ti - quo * base;
 315                   *--bp = digits[rem];
 316                   ti = quo;
 317                   ++ndig_for_this_limb;
 318                 }
 319 # else
 320             while (ti != 0)
 321               {
 322                 mp_limb_t quo, rem;
 323
 324                 quo = ti / base;
 325                 rem = ti % base;
 326                 *--bp = digits[rem];
 327                 ti = quo;
 328                 ++ndig_for_this_limb;
 329               }
 330 # endif
 331             /* If this wasn't the most significant word, pad with zeros.  */
 332             if (n != 0)
 333               while (ndig_for_this_limb < brec->big.ndigits)
 334                 {
 335                   *--bp = '0';
 336                   ++ndig_for_this_limb;
 337                 }
 338           }
 339         while (n != 0);
 340 # endif
 341       }
 342       break;
 343     }
 344
 345   return bp;
 346 }
 347 #endif