stdio-common/_itowa.c

   1 /* Internal function for converting integers to ASCII.
   2    Copyright (C) 1994-2015 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 (value, buflim, base, upper_case)
  91      unsigned long long int value;
  92      wchar_t *buflim;
  93      unsigned int base;
  94      int upper_case;
  95 {
  96   const wchar_t *digits = (upper_case
  97                            ? _itowa_upper_digits : _itowa_lower_digits);
  98   wchar_t *bp = buflim;
  99   const struct base_table_t *brec = &_itoa_base_table[base - 2];
 100
 101   switch (base)
 102     {
 103 # define RUN_2N(BITS) \
 104       do                                                                      \
 105         {                                                                     \
 106           /* `unsigned long long int' always has 64 bits.  */                 \
 107           mp_limb_t work_hi = value >> (64 - BITS_PER_MP_LIMB);               \
 108                                                                               \
 109           if (BITS_PER_MP_LIMB == 32)                                         \
 110             {                                                                 \
 111               if (work_hi != 0)                                               \
 112                 {                                                             \
 113                   mp_limb_t work_lo;                                          \
 114                   int cnt;                                                    \
 115                                                                               \
 116                   work_lo = value & 0xfffffffful;                             \
 117                   for (cnt = BITS_PER_MP_LIMB / BITS; cnt > 0; --cnt)         \
 118                     {                                                         \
 119                       *--bp = digits[work_lo & ((1ul << BITS) - 1)];          \
 120                       work_lo >>= BITS;                                       \
 121                     }                                                         \
 122                   if (BITS_PER_MP_LIMB % BITS != 0)                           \
 123                     {                                                         \
 124                       work_lo                                                 \
 125                         |= ((work_hi                                          \
 126                              & ((1 << (BITS - BITS_PER_MP_LIMB%BITS))         \
 127                                 - 1))                                         \
 128                             << BITS_PER_MP_LIMB % BITS);                      \
 129                       work_hi >>= BITS - BITS_PER_MP_LIMB % BITS;             \
 130                       if (work_hi == 0)                                       \
 131                         work_hi = work_lo;                                    \
 132                       else                                                    \
 133                         *--bp = digits[work_lo];                              \
 134                     }                                                         \
 135                 }                                                             \
 136               else                                                            \
 137                 work_hi = value & 0xfffffffful;                               \
 138             }                                                                 \
 139           do                                                                  \
 140             {                                                                 \
 141               *--bp = digits[work_hi & ((1 << BITS) - 1)];                    \
 142               work_hi >>= BITS;                                               \
 143             }                                                                 \
 144           while (work_hi != 0);                                               \
 145         }                                                                     \
 146       while (0)
 147     case 8:
 148       RUN_2N (3);
 149       break;
 150
 151     case 16:
 152       RUN_2N (4);
 153       break;
 154
 155     default:
 156       {
 157 # if BITS_PER_MP_LIMB == 64
 158         mp_limb_t base_multiplier = brec->base_multiplier;
 159         if (brec->flag)
 160           while (value != 0)
 161             {
 162               mp_limb_t quo, rem, x;
 163               mp_limb_t dummy __attribute__ ((unused));
 164
 165               umul_ppmm (x, dummy, value, base_multiplier);
 166               quo = (x + ((value - x) >> 1)) >> (brec->post_shift - 1);
 167               rem = value - quo * base;
 168               *--bp = digits[rem];
 169               value = quo;
 170             }
 171         else
 172           while (value != 0)
 173             {
 174               mp_limb_t quo, rem, x;
 175               mp_limb_t dummy __attribute__ ((unused));
 176
 177               umul_ppmm (x, dummy, value, base_multiplier);
 178               quo = x >> brec->post_shift;
 179               rem = value - quo * base;
 180               *--bp = digits[rem];
 181               value = quo;
 182             }
 183 # endif
 184 # if BITS_PER_MP_LIMB == 32
 185         mp_limb_t t[3];
 186         int n;
 187
 188         /* First convert x0 to 1-3 words in base s->big.base.
 189            Optimize for frequent cases of 32 bit numbers.  */
 190         if ((mp_limb_t) (value >> 32) >= 1)
 191           {
 192 # if UDIV_TIME > 2 * UMUL_TIME || UDIV_NEEDS_NORMALIZATION
 193             int big_normalization_steps = brec->big.normalization_steps;
 194             mp_limb_t big_base_norm
 195               = brec->big.base << big_normalization_steps;
 196 # endif
 197             if ((mp_limb_t) (value >> 32) >= brec->big.base)
 198               {
 199                 mp_limb_t x1hi, x1lo, r;
 200                 /* If you want to optimize this, take advantage of
 201                    that the quotient in the first udiv_qrnnd will
 202                    always be very small.  It might be faster just to
 203                    subtract in a tight loop.  */
 204
 205 # if UDIV_TIME > 2 * UMUL_TIME
 206                 mp_limb_t x, xh, xl;
 207
 208                 if (big_normalization_steps == 0)
 209                   xh = 0;
 210                 else
 211                   xh = (mp_limb_t) (value >> (64 - big_normalization_steps));
 212                 xl = (mp_limb_t) (value >> (32 - big_normalization_steps));
 213                 udiv_qrnnd_preinv (x1hi, r, xh, xl, big_base_norm,
 214                                    brec->big.base_ninv);
 215
 216                 xl = ((mp_limb_t) value) << big_normalization_steps;
 217                 udiv_qrnnd_preinv (x1lo, x, r, xl, big_base_norm,
 218                                    brec->big.base_ninv);
 219                 t[2] = x >> big_normalization_steps;
 220
 221                 if (big_normalization_steps == 0)
 222                   xh = x1hi;
 223                 else
 224                   xh = ((x1hi << big_normalization_steps)
 225                         | (x1lo >> (32 - big_normalization_steps)));
 226                 xl = x1lo << big_normalization_steps;
 227                 udiv_qrnnd_preinv (t[0], x, xh, xl, big_base_norm,
 228                                    brec->big.base_ninv);
 229                 t[1] = x >> big_normalization_steps;
 230 # elif UDIV_NEEDS_NORMALIZATION
 231                 mp_limb_t x, xh, xl;
 232
 233                 if (big_normalization_steps == 0)
 234                   xh = 0;
 235                 else
 236                   xh = (mp_limb_t) (value >> 64 - big_normalization_steps);
 237                 xl = (mp_limb_t) (value >> 32 - big_normalization_steps);
 238                 udiv_qrnnd (x1hi, r, xh, xl, big_base_norm);
 239
 240                 xl = ((mp_limb_t) value) << big_normalization_steps;
 241                 udiv_qrnnd (x1lo, x, r, xl, big_base_norm);
 242                 t[2] = x >> big_normalization_steps;
 243
 244                 if (big_normalization_steps == 0)
 245                   xh = x1hi;
 246                 else
 247                   xh = ((x1hi << big_normalization_steps)
 248                         | (x1lo >> 32 - big_normalization_steps));
 249                 xl = x1lo << big_normalization_steps;
 250                 udiv_qrnnd (t[0], x, xh, xl, big_base_norm);
 251                 t[1] = x >> big_normalization_steps;
 252 # else
 253                 udiv_qrnnd (x1hi, r, 0, (mp_limb_t) (value >> 32),
 254                             brec->big.base);
 255                 udiv_qrnnd (x1lo, t[2], r, (mp_limb_t) value, brec->big.base);
 256                 udiv_qrnnd (t[0], t[1], x1hi, x1lo, brec->big.base);
 257 # endif
 258                 n = 3;
 259               }
 260             else
 261               {
 262 # if UDIV_TIME > 2 * UMUL_TIME
 263                 mp_limb_t x;
 264
 265                 value <<= brec->big.normalization_steps;
 266                 udiv_qrnnd_preinv (t[0], x, (mp_limb_t) (value >> 32),
 267                                    (mp_limb_t) value, big_base_norm,
 268                                    brec->big.base_ninv);
 269                 t[1] = x >> brec->big.normalization_steps;
 270 # elif UDIV_NEEDS_NORMALIZATION
 271                 mp_limb_t x;
 272
 273                 value <<= big_normalization_steps;
 274                 udiv_qrnnd (t[0], x, (mp_limb_t) (value >> 32),
 275                             (mp_limb_t) value, big_base_norm);
 276                 t[1] = x >> big_normalization_steps;
 277 # else
 278                 udiv_qrnnd (t[0], t[1], (mp_limb_t) (value >> 32),
 279                             (mp_limb_t) value, brec->big.base);
 280 # endif
 281                 n = 2;
 282               }
 283           }
 284         else
 285           {
 286             t[0] = value;
 287             n = 1;
 288           }
 289
 290         /* Convert the 1-3 words in t[], word by word, to ASCII.  */
 291         do
 292           {
 293             mp_limb_t ti = t[--n];
 294             int ndig_for_this_limb = 0;
 295
 296 # if UDIV_TIME > 2 * UMUL_TIME
 297             mp_limb_t base_multiplier = brec->base_multiplier;
 298             if (brec->flag)
 299               while (ti != 0)
 300                 {
 301                   mp_limb_t quo, rem, x;
 302                   mp_limb_t dummy __attribute__ ((unused));
 303
 304                   umul_ppmm (x, dummy, ti, base_multiplier);
 305                   quo = (x + ((ti - x) >> 1)) >> (brec->post_shift - 1);
 306                   rem = ti - quo * base;
 307                   *--bp = digits[rem];
 308                   ti = quo;
 309                   ++ndig_for_this_limb;
 310                 }
 311             else
 312               while (ti != 0)
 313                 {
 314                   mp_limb_t quo, rem, x;
 315                   mp_limb_t dummy __attribute__ ((unused));
 316
 317                   umul_ppmm (x, dummy, ti, base_multiplier);
 318                   quo = x >> brec->post_shift;
 319                   rem = ti - quo * base;
 320                   *--bp = digits[rem];
 321                   ti = quo;
 322                   ++ndig_for_this_limb;
 323                 }
 324 # else
 325             while (ti != 0)
 326               {
 327                 mp_limb_t quo, rem;
 328
 329                 quo = ti / base;
 330                 rem = ti % base;
 331                 *--bp = digits[rem];
 332                 ti = quo;
 333                 ++ndig_for_this_limb;
 334               }
 335 # endif
 336             /* If this wasn't the most significant word, pad with zeros.  */
 337             if (n != 0)
 338               while (ndig_for_this_limb < brec->big.ndigits)
 339                 {
 340                   *--bp = '0';
 341                   ++ndig_for_this_limb;
 342                 }
 343           }
 344         while (n != 0);
 345 # endif
 346       }
 347       break;
 348     }
 349
 350   return bp;
 351 }
 352 #endif