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glibc/stdio-common/_itowa.c

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/* Internal function for converting integers to ASCII.
Copyright (C) 1994-2018 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, see
<http://www.gnu.org/licenses/>. */
#include <gmp-mparam.h>
#include <gmp.h>
#include <limits.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;
#if _ITOA_NEEDED
wchar_t *
_itowa (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;
mp_limb_t dummy __attribute__ ((unused));
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;
mp_limb_t dummy __attribute__ ((unused));
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;
mp_limb_t dummy __attribute__ ((unused));
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;
mp_limb_t dummy __attribute__ ((unused));
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;
}
#endif
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