stdio-common/_itowa.c

   1 /* Internal function for converting integers to ASCII.
   2    Copyright (C) 1994-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Torbjorn Granlund <tege@matematik.su.se>
   5    and Ulrich Drepper <drepper@gnu.org>.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <gmp-mparam.h>
  22 #include <gmp.h>
  23 #include <limits.h>
  24 #include <stdlib/gmp-impl.h>
  25 #include <stdlib/longlong.h>
  26
  27 #include <_itowa.h>
  28
  29
  30 /* Canonize environment.  For some architectures not all values might
  31    be defined in the GMP header files.  */
  32 #ifndef UMUL_TIME
  33 # define UMUL_TIME 1
  34 #endif
  35 #ifndef UDIV_TIME
  36 # define UDIV_TIME 3
  37 #endif
  38
  39 /* Control memory layout.  */
  40 #ifdef PACK
  41 # undef PACK
  42 # define PACK __attribute__ ((packed))
  43 #else
  44 # define PACK
  45 #endif
  46
  47
  48 /* Declare local types.  */
  49 struct base_table_t
  50 {
  51 #if (UDIV_TIME > 2 * UMUL_TIME)
  52   mp_limb_t base_multiplier;
  53 #endif
  54   char flag;
  55   char post_shift;
  56 #if BITS_PER_MP_LIMB == 32
  57   struct
  58     {
  59       char normalization_steps;
  60       char ndigits;
  61       mp_limb_t base PACK;
  62 #if UDIV_TIME > 2 * UMUL_TIME
  63       mp_limb_t base_ninv PACK;
  64 #endif
  65     } big;
  66 #endif
  67 };
  68
  69 /* To reduce the memory needed we include some fields of the tables
  70    only conditionally.  */
  71 #if UDIV_TIME > 2 * UMUL_TIME
  72 # define SEL1(X) X,
  73 # define SEL2(X) ,X
  74 #else
  75 # define SEL1(X)
  76 # define SEL2(X)
  77 #endif
  78
  79 /* Factor table for the different bases.  */
  80 extern const struct base_table_t _itoa_base_table[] attribute_hidden;
  81
  82 /* Lower-case digits.  */
  83 extern const wchar_t _itowa_lower_digits[] attribute_hidden;
  84 /* Upper-case digits.  */
  85 extern const wchar_t _itowa_upper_digits[] attribute_hidden;
  86
  87
  88 #if _ITOA_NEEDED
  89 wchar_t *
  90 _itowa (unsigned long long int value, wchar_t *buflim, unsigned int base,
  91         int upper_case)
  92 {
  93   const wchar_t *digits = (upper_case
  94                            ? _itowa_upper_digits : _itowa_lower_digits);
  95   wchar_t *bp = buflim;
  96   const struct base_table_t *brec = &_itoa_base_table[base - 2];
  97
  98   switch (base)
  99     {
 100 # define RUN_2N(BITS) \
 101       do                                                                      \
 102         {                                                                     \
 103           /* `unsigned long long int' always has 64 bits.  */                 \
 104           mp_limb_t work_hi = value >> (64 - BITS_PER_MP_LIMB);               \
 105                                                                               \
 106           if (BITS_PER_MP_LIMB == 32)                                         \
 107             {                                                                 \
 108               if (work_hi != 0)                                               \
 109                 {                                                             \
 110                   mp_limb_t work_lo;                                          \
 111                   int cnt;                                                    \
 112                                                                               \
 113                   work_lo = value & 0xfffffffful;                             \
 114                   for (cnt = BITS_PER_MP_LIMB / BITS; cnt > 0; --cnt)         \
 115                     {                                                         \
 116                       *--bp = digits[work_lo & ((1ul << BITS) - 1)];          \
 117                       work_lo >>= BITS;                                       \
 118                     }                                                         \
 119                   if (BITS_PER_MP_LIMB % BITS != 0)                           \
 120                     {                                                         \
 121                       work_lo                                                 \
 122                         |= ((work_hi                                          \
 123                              & ((1 << (BITS - BITS_PER_MP_LIMB%BITS))         \
 124                                 - 1))                                         \
 125                             << BITS_PER_MP_LIMB % BITS);                      \
 126                       work_hi >>= BITS - BITS_PER_MP_LIMB % BITS;             \
 127                       if (work_hi == 0)                                       \
 128                         work_hi = work_lo;                                    \
 129                       else                                                    \
 130                         *--bp = digits[work_lo];                              \
 131                     }                                                         \
 132                 }                                                             \
 133               else                                                            \
 134                 work_hi = value & 0xfffffffful;                               \
 135             }                                                                 \
 136           do                                                                  \
 137             {                                                                 \
 138               *--bp = digits[work_hi & ((1 << BITS) - 1)];                    \
 139               work_hi >>= BITS;                                               \
 140             }                                                                 \
 141           while (work_hi != 0);                                               \
 142         }                                                                     \
 143       while (0)
 144     case 8:
 145       RUN_2N (3);
 146       break;
 147
 148     case 16:
 149       RUN_2N (4);
 150       break;
 151
 152     default:
 153       {
 154 # if BITS_PER_MP_LIMB == 64
 155         mp_limb_t base_multiplier = brec->base_multiplier;
 156         if (brec->flag)
 157           while (value != 0)
 158             {
 159               mp_limb_t quo, rem, x;
 160               mp_limb_t dummy __attribute__ ((unused));
 161
 162               umul_ppmm (x, dummy, value, base_multiplier);
 163               quo = (x + ((value - x) >> 1)) >> (brec->post_shift - 1);
 164               rem = value - quo * base;
 165               *--bp = digits[rem];
 166               value = quo;
 167             }
 168         else
 169           while (value != 0)
 170             {
 171               mp_limb_t quo, rem, x;
 172               mp_limb_t dummy __attribute__ ((unused));
 173
 174               umul_ppmm (x, dummy, value, base_multiplier);
 175               quo = x >> brec->post_shift;
 176               rem = value - quo * base;
 177               *--bp = digits[rem];
 178               value = quo;
 179             }
 180 # endif
 181 # if BITS_PER_MP_LIMB == 32
 182         mp_limb_t t[3];
 183         int n;
 184
 185         /* First convert x0 to 1-3 words in base s->big.base.
 186            Optimize for frequent cases of 32 bit numbers.  */
 187         if ((mp_limb_t) (value >> 32) >= 1)
 188           {
 189 # if UDIV_TIME > 2 * UMUL_TIME || UDIV_NEEDS_NORMALIZATION
 190             int big_normalization_steps = brec->big.normalization_steps;
 191             mp_limb_t big_base_norm
 192               = brec->big.base << big_normalization_steps;
 193 # endif
 194             if ((mp_limb_t) (value >> 32) >= brec->big.base)
 195               {
 196                 mp_limb_t x1hi, x1lo, r;
 197                 /* If you want to optimize this, take advantage of
 198                    that the quotient in the first udiv_qrnnd will
 199                    always be very small.  It might be faster just to
 200                    subtract in a tight loop.  */
 201
 202 # if UDIV_TIME > 2 * UMUL_TIME
 203                 mp_limb_t x, xh, xl;
 204
 205                 if (big_normalization_steps == 0)
 206                   xh = 0;
 207                 else
 208                   xh = (mp_limb_t) (value >> (64 - big_normalization_steps));
 209                 xl = (mp_limb_t) (value >> (32 - big_normalization_steps));
 210                 udiv_qrnnd_preinv (x1hi, r, xh, xl, big_base_norm,
 211                                    brec->big.base_ninv);
 212
 213                 xl = ((mp_limb_t) value) << big_normalization_steps;
 214                 udiv_qrnnd_preinv (x1lo, x, r, xl, big_base_norm,
 215                                    brec->big.base_ninv);
 216                 t[2] = x >> big_normalization_steps;
 217
 218                 if (big_normalization_steps == 0)
 219                   xh = x1hi;
 220                 else
 221                   xh = ((x1hi << big_normalization_steps)
 222                         | (x1lo >> (32 - big_normalization_steps)));
 223                 xl = x1lo << big_normalization_steps;
 224                 udiv_qrnnd_preinv (t[0], x, xh, xl, big_base_norm,
 225                                    brec->big.base_ninv);
 226                 t[1] = x >> big_normalization_steps;
 227 # elif UDIV_NEEDS_NORMALIZATION
 228                 mp_limb_t x, xh, xl;
 229
 230                 if (big_normalization_steps == 0)
 231                   xh = 0;
 232                 else
 233                   xh = (mp_limb_t) (value >> 64 - big_normalization_steps);
 234                 xl = (mp_limb_t) (value >> 32 - big_normalization_steps);
 235                 udiv_qrnnd (x1hi, r, xh, xl, big_base_norm);
 236
 237                 xl = ((mp_limb_t) value) << big_normalization_steps;
 238                 udiv_qrnnd (x1lo, x, r, xl, big_base_norm);
 239                 t[2] = x >> big_normalization_steps;
 240
 241                 if (big_normalization_steps == 0)
 242                   xh = x1hi;
 243                 else
 244                   xh = ((x1hi << big_normalization_steps)
 245                         | (x1lo >> 32 - big_normalization_steps));
 246                 xl = x1lo << big_normalization_steps;
 247                 udiv_qrnnd (t[0], x, xh, xl, big_base_norm);
 248                 t[1] = x >> big_normalization_steps;
 249 # else
 250                 udiv_qrnnd (x1hi, r, 0, (mp_limb_t) (value >> 32),
 251                             brec->big.base);
 252                 udiv_qrnnd (x1lo, t[2], r, (mp_limb_t) value, brec->big.base);
 253                 udiv_qrnnd (t[0], t[1], x1hi, x1lo, brec->big.base);
 254 # endif
 255                 n = 3;
 256               }
 257             else
 258               {
 259 # if UDIV_TIME > 2 * UMUL_TIME
 260                 mp_limb_t x;
 261
 262                 value <<= brec->big.normalization_steps;
 263                 udiv_qrnnd_preinv (t[0], x, (mp_limb_t) (value >> 32),
 264                                    (mp_limb_t) value, big_base_norm,
 265                                    brec->big.base_ninv);
 266                 t[1] = x >> brec->big.normalization_steps;
 267 # elif UDIV_NEEDS_NORMALIZATION
 268                 mp_limb_t x;
 269
 270                 value <<= big_normalization_steps;
 271                 udiv_qrnnd (t[0], x, (mp_limb_t) (value >> 32),
 272                             (mp_limb_t) value, big_base_norm);
 273                 t[1] = x >> big_normalization_steps;
 274 # else
 275                 udiv_qrnnd (t[0], t[1], (mp_limb_t) (value >> 32),
 276                             (mp_limb_t) value, brec->big.base);
 277 # endif
 278                 n = 2;
 279               }
 280           }
 281         else
 282           {
 283             t[0] = value;
 284             n = 1;
 285           }
 286
 287         /* Convert the 1-3 words in t[], word by word, to ASCII.  */
 288         do
 289           {
 290             mp_limb_t ti = t[--n];
 291             int ndig_for_this_limb = 0;
 292
 293 # if UDIV_TIME > 2 * UMUL_TIME
 294             mp_limb_t base_multiplier = brec->base_multiplier;
 295             if (brec->flag)
 296               while (ti != 0)
 297                 {
 298                   mp_limb_t quo, rem, x;
 299                   mp_limb_t dummy __attribute__ ((unused));
 300
 301                   umul_ppmm (x, dummy, ti, base_multiplier);
 302                   quo = (x + ((ti - x) >> 1)) >> (brec->post_shift - 1);
 303                   rem = ti - quo * base;
 304                   *--bp = digits[rem];
 305                   ti = quo;
 306                   ++ndig_for_this_limb;
 307                 }
 308             else
 309               while (ti != 0)
 310                 {
 311                   mp_limb_t quo, rem, x;
 312                   mp_limb_t dummy __attribute__ ((unused));
 313
 314                   umul_ppmm (x, dummy, ti, base_multiplier);
 315                   quo = x >> brec->post_shift;
 316                   rem = ti - quo * base;
 317                   *--bp = digits[rem];
 318                   ti = quo;
 319                   ++ndig_for_this_limb;
 320                 }
 321 # else
 322             while (ti != 0)
 323               {
 324                 mp_limb_t quo, rem;
 325
 326                 quo = ti / base;
 327                 rem = ti % base;
 328                 *--bp = digits[rem];
 329                 ti = quo;
 330                 ++ndig_for_this_limb;
 331               }
 332 # endif
 333             /* If this wasn't the most significant word, pad with zeros.  */
 334             if (n != 0)
 335               while (ndig_for_this_limb < brec->big.ndigits)
 336                 {
 337                   *--bp = '0';
 338                   ++ndig_for_this_limb;
 339                 }
 340           }
 341         while (n != 0);
 342 # endif
 343       }
 344       break;
 345     }
 346
 347   return bp;
 348 }
 349 #endif