390 lines
8.8 KiB
C
390 lines
8.8 KiB
C
/* mpf_set_str (dest, string, base) -- Convert the string STRING
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in base BASE to a float in dest. If BASE is zero, the leading characters
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of STRING is used to figure out the base.
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Copyright 1993, 1994, 1995, 1996, 1997, 2000, 2001, 2002, 2003, 2005, 2007,
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2008 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/*
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This still needs work, as suggested by some FIXME comments.
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1. Don't depend on superfluous mantissa digits.
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2. Allocate temp space more cleverly.
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3. Use mpn_tdiv_qr instead of mpn_lshift+mpn_divrem.
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*/
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#define _GNU_SOURCE /* for DECIMAL_POINT in langinfo.h */
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#include "config.h"
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#if HAVE_LANGINFO_H
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#include <langinfo.h> /* for nl_langinfo */
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#endif
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#if HAVE_LOCALE_H
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#include <locale.h> /* for localeconv */
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#endif
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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extern const unsigned char __gmp_digit_value_tab[];
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#define digit_value_tab __gmp_digit_value_tab
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/* Compute base^exp and return the most significant prec limbs in rp[].
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Put the count of omitted low limbs in *ign.
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Return the actual size (which might be less than prec). */
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static mp_size_t
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mpn_pow_1_highpart (mp_ptr rp, mp_size_t *ignp,
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mp_limb_t base, mp_exp_t exp,
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mp_size_t prec, mp_ptr tp)
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{
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mp_size_t ign; /* counts number of ignored low limbs in r */
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mp_size_t off; /* keeps track of offset where value starts */
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mp_ptr passed_rp = rp;
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mp_size_t rn;
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int cnt;
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int i;
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rp[0] = base;
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rn = 1;
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off = 0;
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ign = 0;
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count_leading_zeros (cnt, exp);
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for (i = GMP_LIMB_BITS - cnt - 2; i >= 0; i--)
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{
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mpn_sqr_n (tp, rp + off, rn);
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rn = 2 * rn;
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rn -= tp[rn - 1] == 0;
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ign <<= 1;
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off = 0;
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if (rn > prec)
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{
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ign += rn - prec;
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off = rn - prec;
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rn = prec;
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}
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MP_PTR_SWAP (rp, tp);
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if (((exp >> i) & 1) != 0)
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{
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mp_limb_t cy;
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cy = mpn_mul_1 (rp, rp + off, rn, base);
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rp[rn] = cy;
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rn += cy != 0;
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off = 0;
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}
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}
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if (rn > prec)
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{
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ign += rn - prec;
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rp += rn - prec;
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rn = prec;
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}
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MPN_COPY_INCR (passed_rp, rp + off, rn);
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*ignp = ign;
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return rn;
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}
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int
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mpf_set_str (mpf_ptr x, const char *str, int base)
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{
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size_t str_size;
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char *s, *begs;
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size_t i, j;
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int c;
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int negative;
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char *dotpos = 0;
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const char *expptr;
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int exp_base;
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const char *point = GMP_DECIMAL_POINT;
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size_t pointlen = strlen (point);
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const unsigned char *digit_value;
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TMP_DECL;
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c = (unsigned char) *str;
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/* Skip whitespace. */
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while (isspace (c))
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c = (unsigned char) *++str;
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negative = 0;
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if (c == '-')
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{
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negative = 1;
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c = (unsigned char) *++str;
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}
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exp_base = base;
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if (base < 0)
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{
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exp_base = 10;
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base = -base;
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}
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digit_value = digit_value_tab;
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if (base > 36)
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{
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/* For bases > 36, use the collating sequence
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0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz. */
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digit_value += 224;
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if (base > 62)
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return -1; /* too large base */
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}
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/* Require at least one digit, possibly after an initial decimal point. */
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if (digit_value[c] >= (base == 0 ? 10 : base))
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{
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/* not a digit, must be a decimal point */
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for (i = 0; i < pointlen; i++)
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if (str[i] != point[i])
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return -1;
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if (digit_value[(unsigned char) str[pointlen]] >= (base == 0 ? 10 : base))
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return -1;
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}
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/* Default base to decimal. */
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if (base == 0)
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base = 10;
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/* Locate exponent part of the input. Look from the right of the string,
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since the exponent is usually a lot shorter than the mantissa. */
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expptr = NULL;
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str_size = strlen (str);
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for (i = str_size - 1; i > 0; i--)
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{
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c = (unsigned char) str[i];
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if (c == '@' || (base <= 10 && (c == 'e' || c == 'E')))
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{
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expptr = str + i + 1;
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str_size = i;
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break;
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}
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}
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TMP_MARK;
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s = begs = (char *) TMP_ALLOC (str_size + 1);
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/* Loop through mantissa, converting it from ASCII to raw byte values. */
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for (i = 0; i < str_size; i++)
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{
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c = (unsigned char) *str;
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if (!isspace (c))
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{
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int dig;
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for (j = 0; j < pointlen; j++)
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if (str[j] != point[j])
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goto not_point;
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if (1)
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{
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if (dotpos != 0)
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{
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/* already saw a decimal point, another is invalid */
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TMP_FREE;
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return -1;
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}
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dotpos = s;
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str += pointlen - 1;
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i += pointlen - 1;
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}
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else
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{
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not_point:
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dig = digit_value[c];
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if (dig >= base)
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{
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TMP_FREE;
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return -1;
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}
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*s++ = dig;
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}
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}
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c = (unsigned char) *++str;
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}
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str_size = s - begs;
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{
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long exp_in_base;
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mp_size_t ra, ma, rn, mn;
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int cnt;
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mp_ptr mp, tp, rp;
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mp_exp_t exp_in_limbs;
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mp_size_t prec = PREC(x) + 1;
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int divflag;
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mp_size_t madj, radj;
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#if 0
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size_t n_chars_needed;
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/* This breaks things like 0.000...0001. To safely ignore superfluous
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digits, we need to skip over leadng zeros. */
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/* Just consider the relevant leading digits of the mantissa. */
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n_chars_needed = 2 + (size_t)
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(((size_t) prec * GMP_NUMB_BITS) * mp_bases[base].chars_per_bit_exactly);
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if (str_size > n_chars_needed)
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str_size = n_chars_needed;
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#endif
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ma = (((mp_size_t) (str_size / mp_bases[base].chars_per_bit_exactly))
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/ GMP_NUMB_BITS + 2);
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mp = TMP_ALLOC_LIMBS (ma);
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mn = mpn_set_str (mp, (unsigned char *) begs, str_size, base);
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if (mn == 0)
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{
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SIZ(x) = 0;
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EXP(x) = 0;
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TMP_FREE;
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return 0;
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}
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madj = 0;
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/* Ignore excess limbs in MP,MSIZE. */
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if (mn > prec)
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{
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madj = mn - prec;
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mp += mn - prec;
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mn = prec;
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}
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if (expptr != 0)
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{
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/* Scan and convert the exponent, in base exp_base. */
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long dig, neg = -(long) ('-' == expptr[0]);
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expptr -= neg; /* conditional increment */
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c = (unsigned char) *expptr++;
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dig = digit_value[c];
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if (dig >= exp_base)
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{
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TMP_FREE;
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return -1;
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}
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exp_in_base = dig;
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c = (unsigned char) *expptr++;
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dig = digit_value[c];
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while (dig < exp_base)
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{
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exp_in_base = exp_in_base * exp_base;
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exp_in_base += dig;
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c = (unsigned char) *expptr++;
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dig = digit_value[c];
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}
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exp_in_base = (exp_in_base ^ neg) - neg; /* conditional negation */
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}
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else
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exp_in_base = 0;
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if (dotpos != 0)
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exp_in_base -= s - dotpos;
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divflag = exp_in_base < 0;
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exp_in_base = ABS (exp_in_base);
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if (exp_in_base == 0)
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{
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MPN_COPY (PTR(x), mp, mn);
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SIZ(x) = negative ? -mn : mn;
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EXP(x) = mn + madj;
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TMP_FREE;
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return 0;
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}
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ra = 2 * (prec + 1);
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rp = TMP_ALLOC_LIMBS (ra);
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tp = TMP_ALLOC_LIMBS (ra);
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rn = mpn_pow_1_highpart (rp, &radj, (mp_limb_t) base, exp_in_base, prec, tp);
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if (divflag)
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{
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#if 0
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/* FIXME: Should use mpn_tdiv here. */
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mpn_tdiv_qr (qp, mp, 0L, mp, mn, rp, rn);
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#else
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mp_ptr qp;
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mp_limb_t qlimb;
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if (mn < rn)
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{
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/* Pad out MP,MSIZE for current divrem semantics. */
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mp_ptr tmp = TMP_ALLOC_LIMBS (rn + 1);
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MPN_ZERO (tmp, rn - mn);
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MPN_COPY (tmp + rn - mn, mp, mn);
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mp = tmp;
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madj -= rn - mn;
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mn = rn;
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}
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if ((rp[rn - 1] & GMP_NUMB_HIGHBIT) == 0)
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{
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mp_limb_t cy;
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count_leading_zeros (cnt, rp[rn - 1]);
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cnt -= GMP_NAIL_BITS;
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mpn_lshift (rp, rp, rn, cnt);
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cy = mpn_lshift (mp, mp, mn, cnt);
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if (cy)
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mp[mn++] = cy;
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}
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qp = TMP_ALLOC_LIMBS (prec + 1);
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qlimb = mpn_divrem (qp, prec - (mn - rn), mp, mn, rp, rn);
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tp = qp;
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exp_in_limbs = qlimb + (mn - rn) + (madj - radj);
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rn = prec;
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if (qlimb != 0)
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{
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tp[prec] = qlimb;
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/* Skip the least significant limb not to overrun the destination
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variable. */
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tp++;
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}
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#endif
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}
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else
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{
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tp = TMP_ALLOC_LIMBS (rn + mn);
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if (rn > mn)
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mpn_mul (tp, rp, rn, mp, mn);
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else
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mpn_mul (tp, mp, mn, rp, rn);
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rn += mn;
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rn -= tp[rn - 1] == 0;
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exp_in_limbs = rn + madj + radj;
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if (rn > prec)
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{
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tp += rn - prec;
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rn = prec;
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exp_in_limbs += 0;
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}
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}
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MPN_COPY (PTR(x), tp, rn);
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SIZ(x) = negative ? -rn : rn;
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EXP(x) = exp_in_limbs;
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TMP_FREE;
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return 0;
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}
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}
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