Logo Search packages:      
Sourcecode: glibc version File versions

_itowa.c

/* Internal function for converting integers to ASCII.
   Copyright (C) 1994,1995,1996,1999,2000,2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Torbjorn Granlund <tege@matematik.su.se>
   and Ulrich Drepper <drepper@gnu.org>.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <gmp-mparam.h>
#include <gmp.h>
#include <stdlib/gmp-impl.h>
#include <stdlib/longlong.h>

#include "_itowa.h"


/* Canonize environment.  For some architectures not all values might
   be defined in the GMP header files.  */
#ifndef UMUL_TIME
# define UMUL_TIME 1
#endif
#ifndef UDIV_TIME
# define UDIV_TIME 3
#endif

/* Control memory layout.  */
#ifdef PACK
# undef PACK
# define PACK __attribute__ ((packed))
#else
# define PACK
#endif


/* Declare local types.  */
struct base_table_t
{
#if (UDIV_TIME > 2 * UMUL_TIME)
  mp_limb_t base_multiplier;
#endif
  char flag;
  char post_shift;
#if BITS_PER_MP_LIMB == 32
  struct
    {
      char normalization_steps;
      char ndigits;
      mp_limb_t base PACK;
#if UDIV_TIME > 2 * UMUL_TIME
      mp_limb_t base_ninv PACK;
#endif
    } big;
#endif
};

/* To reduce the memory needed we include some fields of the tables
   only conditionally.  */
#if UDIV_TIME > 2 * UMUL_TIME
# define SEL1(X) X,
# define SEL2(X) ,X
#else
# define SEL1(X)
# define SEL2(X)
#endif

/* Factor table for the different bases.  */
extern const struct base_table_t _itoa_base_table[] attribute_hidden;

/* Lower-case digits.  */
extern const wchar_t _itowa_lower_digits[] attribute_hidden;
/* Upper-case digits.  */
extern const wchar_t _itowa_upper_digits[] attribute_hidden;


wchar_t *
_itowa (value, buflim, base, upper_case)
     unsigned long long int value;
     wchar_t *buflim;
     unsigned int base;
     int upper_case;
{
  const wchar_t *digits = (upper_case
                     ? _itowa_upper_digits : _itowa_lower_digits);
  wchar_t *bp = buflim;
  const struct base_table_t *brec = &_itoa_base_table[base - 2];

  switch (base)
    {
#define RUN_2N(BITS) \
      do                                                    \
        {                                                   \
        /* `unsigned long long int' always has 64 bits.  */             \
        mp_limb_t work_hi = value >> (64 - BITS_PER_MP_LIMB);                 \
                                                            \
        if (BITS_PER_MP_LIMB == 32)                               \
          {                                                 \
            if (work_hi != 0)                                     \
            {                                               \
              mp_limb_t work_lo;                                  \
              int cnt;                                      \
                                                            \
              work_lo = value & 0xfffffffful;                     \
              for (cnt = BITS_PER_MP_LIMB / BITS; cnt > 0; --cnt)       \
                {                                           \
                  *--bp = digits[work_lo & ((1ul << BITS) - 1)];        \
                  work_lo >>= BITS;                               \
                }                                           \
              if (BITS_PER_MP_LIMB % BITS != 0)                   \
                {                                           \
                  work_lo                                         \
                  |= ((work_hi                                    \
                       & ((1 << (BITS - BITS_PER_MP_LIMB%BITS))         \
                        - 1))                               \
                      << BITS_PER_MP_LIMB % BITS);                \
                  work_hi >>= BITS - BITS_PER_MP_LIMB % BITS;           \
                  if (work_hi == 0)                               \
                  work_hi = work_lo;                              \
                  else                                      \
                  *--bp = digits[work_lo];                        \
                }                                           \
            }                                               \
            else                                            \
            work_hi = value & 0xfffffffful;                             \
          }                                                 \
        do                                                  \
          {                                                 \
            *--bp = digits[work_hi & ((1 << BITS) - 1)];                \
            work_hi >>= BITS;                                     \
          }                                                 \
        while (work_hi != 0);                                     \
      }                                                     \
      while (0)
    case 8:
      RUN_2N (3);
      break;

    case 16:
      RUN_2N (4);
      break;

    default:
      {
#if BITS_PER_MP_LIMB == 64
      mp_limb_t base_multiplier = brec->base_multiplier;
      if (brec->flag)
        while (value != 0)
          {
            mp_limb_t quo, rem, x, dummy;

            umul_ppmm (x, dummy, value, base_multiplier);
            quo = (x + ((value - x) >> 1)) >> (brec->post_shift - 1);
            rem = value - quo * base;
            *--bp = digits[rem];
            value = quo;
          }
      else
        while (value != 0)
          {
            mp_limb_t quo, rem, x, dummy;

            umul_ppmm (x, dummy, value, base_multiplier);
            quo = x >> brec->post_shift;
            rem = value - quo * base;
            *--bp = digits[rem];
            value = quo;
          }
#endif
#if BITS_PER_MP_LIMB == 32
      mp_limb_t t[3];
      int n;

      /* First convert x0 to 1-3 words in base s->big.base.
         Optimize for frequent cases of 32 bit numbers.  */
      if ((mp_limb_t) (value >> 32) >= 1)
        {
#if UDIV_TIME > 2 * UMUL_TIME || UDIV_NEEDS_NORMALIZATION
          int big_normalization_steps = brec->big.normalization_steps;
          mp_limb_t big_base_norm
            = brec->big.base << big_normalization_steps;
#endif
          if ((mp_limb_t) (value >> 32) >= brec->big.base)
            {
            mp_limb_t x1hi, x1lo, r;
            /* If you want to optimize this, take advantage of
               that the quotient in the first udiv_qrnnd will
               always be very small.  It might be faster just to
               subtract in a tight loop.  */

#if UDIV_TIME > 2 * UMUL_TIME
            mp_limb_t x, xh, xl;

            if (big_normalization_steps == 0)
              xh = 0;
            else
              xh = (mp_limb_t) (value >> (64 - big_normalization_steps));
            xl = (mp_limb_t) (value >> (32 - big_normalization_steps));
            udiv_qrnnd_preinv (x1hi, r, xh, xl, big_base_norm,
                           brec->big.base_ninv);

            xl = ((mp_limb_t) value) << big_normalization_steps;
            udiv_qrnnd_preinv (x1lo, x, r, xl, big_base_norm,
                           brec->big.base_ninv);
            t[2] = x >> big_normalization_steps;

            if (big_normalization_steps == 0)
              xh = x1hi;
            else
              xh = ((x1hi << big_normalization_steps)
                  | (x1lo >> (32 - big_normalization_steps)));
            xl = x1lo << big_normalization_steps;
            udiv_qrnnd_preinv (t[0], x, xh, xl, big_base_norm,
                           brec->big.base_ninv);
            t[1] = x >> big_normalization_steps;
#elif UDIV_NEEDS_NORMALIZATION
            mp_limb_t x, xh, xl;

            if (big_normalization_steps == 0)
              xh = 0;
            else
              xh = (mp_limb_t) (value >> 64 - big_normalization_steps);
            xl = (mp_limb_t) (value >> 32 - big_normalization_steps);
            udiv_qrnnd (x1hi, r, xh, xl, big_base_norm);

            xl = ((mp_limb_t) value) << big_normalization_steps;
            udiv_qrnnd (x1lo, x, r, xl, big_base_norm);
            t[2] = x >> big_normalization_steps;

            if (big_normalization_steps == 0)
              xh = x1hi;
            else
              xh = ((x1hi << big_normalization_steps)
                  | (x1lo >> 32 - big_normalization_steps));
            xl = x1lo << big_normalization_steps;
            udiv_qrnnd (t[0], x, xh, xl, big_base_norm);
            t[1] = x >> big_normalization_steps;
#else
            udiv_qrnnd (x1hi, r, 0, (mp_limb_t) (value >> 32),
                      brec->big.base);
            udiv_qrnnd (x1lo, t[2], r, (mp_limb_t) value, brec->big.base);
            udiv_qrnnd (t[0], t[1], x1hi, x1lo, brec->big.base);
#endif
            n = 3;
            }
          else
            {
#if (UDIV_TIME > 2 * UMUL_TIME)
            mp_limb_t x;

            value <<= brec->big.normalization_steps;
            udiv_qrnnd_preinv (t[0], x, (mp_limb_t) (value >> 32),
                           (mp_limb_t) value, big_base_norm,
                           brec->big.base_ninv);
            t[1] = x >> brec->big.normalization_steps;
#elif UDIV_NEEDS_NORMALIZATION
            mp_limb_t x;

            value <<= big_normalization_steps;
            udiv_qrnnd (t[0], x, (mp_limb_t) (value >> 32),
                      (mp_limb_t) value, big_base_norm);
            t[1] = x >> big_normalization_steps;
#else
            udiv_qrnnd (t[0], t[1], (mp_limb_t) (value >> 32),
                      (mp_limb_t) value, brec->big.base);
#endif
            n = 2;
            }
        }
      else
        {
          t[0] = value;
          n = 1;
        }

      /* Convert the 1-3 words in t[], word by word, to ASCII.  */
      do
        {
          mp_limb_t ti = t[--n];
          int ndig_for_this_limb = 0;

#if UDIV_TIME > 2 * UMUL_TIME
          mp_limb_t base_multiplier = brec->base_multiplier;
          if (brec->flag)
            while (ti != 0)
            {
              mp_limb_t quo, rem, x, dummy;

              umul_ppmm (x, dummy, ti, base_multiplier);
              quo = (x + ((ti - x) >> 1)) >> (brec->post_shift - 1);
              rem = ti - quo * base;
              *--bp = digits[rem];
              ti = quo;
              ++ndig_for_this_limb;
            }
          else
            while (ti != 0)
            {
              mp_limb_t quo, rem, x, dummy;

              umul_ppmm (x, dummy, ti, base_multiplier);
              quo = x >> brec->post_shift;
              rem = ti - quo * base;
              *--bp = digits[rem];
              ti = quo;
              ++ndig_for_this_limb;
            }
#else
          while (ti != 0)
            {
            mp_limb_t quo, rem;

            quo = ti / base;
            rem = ti % base;
            *--bp = digits[rem];
            ti = quo;
            ++ndig_for_this_limb;
            }
#endif
          /* If this wasn't the most significant word, pad with zeros.  */
          if (n != 0)
            while (ndig_for_this_limb < brec->big.ndigits)
            {
              *--bp = '0';
              ++ndig_for_this_limb;
            }
        }
      while (n != 0);
#endif
      }
      break;
    }

  return bp;
}

Generated by  Doxygen 1.6.0   Back to index