set_str.c
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上传日期:2022-08-06
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- /* mpf_set_str (dest, string, base) -- Convert the string STRING
- in base BASE to a float in dest. If BASE is zero, the leading characters
- of STRING is used to figure out the base.
- Copyright 1993, 1994, 1995, 1996, 1997, 2000, 2001, 2002, 2003, 2005, 2007,
- 2008 Free Software Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP 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 3 of the License, or (at your
- option) any later version.
- The GNU MP 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 MP Library. If not, see http://www.gnu.org/licenses/. */
- /*
- This still needs work, as suggested by some FIXME comments.
- 1. Don't depend on superfluous mantissa digits.
- 2. Allocate temp space more cleverly.
- 3. Use mpn_tdiv_qr instead of mpn_lshift+mpn_divrem.
- */
- #define _GNU_SOURCE /* for DECIMAL_POINT in langinfo.h */
- #include "config.h"
- #include <stdlib.h>
- #include <string.h>
- #include <ctype.h>
- #if HAVE_LANGINFO_H
- #include <langinfo.h> /* for nl_langinfo */
- #endif
- #if HAVE_LOCALE_H
- #include <locale.h> /* for localeconv */
- #endif
- #include "gmp.h"
- #include "gmp-impl.h"
- #include "longlong.h"
- extern const unsigned char __gmp_digit_value_tab[];
- #define digit_value_tab __gmp_digit_value_tab
- /* Compute base^exp and return the most significant prec limbs in rp[].
- Put the count of omitted low limbs in *ign.
- Return the actual size (which might be less than prec). */
- static mp_size_t
- mpn_pow_1_highpart (mp_ptr rp, mp_size_t *ignp,
- mp_limb_t base, mp_exp_t exp,
- mp_size_t prec, mp_ptr tp)
- {
- mp_size_t ign; /* counts number of ignored low limbs in r */
- mp_size_t off; /* keeps track of offset where value starts */
- mp_ptr passed_rp = rp;
- mp_size_t rn;
- int cnt;
- int i;
- rp[0] = base;
- rn = 1;
- off = 0;
- ign = 0;
- count_leading_zeros (cnt, exp);
- for (i = GMP_LIMB_BITS - cnt - 2; i >= 0; i--)
- {
- mpn_sqr (tp, rp + off, rn);
- rn = 2 * rn;
- rn -= tp[rn - 1] == 0;
- ign <<= 1;
- off = 0;
- if (rn > prec)
- {
- ign += rn - prec;
- off = rn - prec;
- rn = prec;
- }
- MP_PTR_SWAP (rp, tp);
- if (((exp >> i) & 1) != 0)
- {
- mp_limb_t cy;
- cy = mpn_mul_1 (rp, rp + off, rn, base);
- rp[rn] = cy;
- rn += cy != 0;
- off = 0;
- }
- }
- if (rn > prec)
- {
- ign += rn - prec;
- rp += rn - prec;
- rn = prec;
- }
- MPN_COPY_INCR (passed_rp, rp + off, rn);
- *ignp = ign;
- return rn;
- }
- int
- mpf_set_str (mpf_ptr x, const char *str, int base)
- {
- size_t str_size;
- char *s, *begs;
- size_t i, j;
- int c;
- int negative;
- char *dotpos = 0;
- const char *expptr;
- int exp_base;
- const char *point = GMP_DECIMAL_POINT;
- size_t pointlen = strlen (point);
- const unsigned char *digit_value;
- TMP_DECL;
- c = (unsigned char) *str;
- /* Skip whitespace. */
- while (isspace (c))
- c = (unsigned char) *++str;
- negative = 0;
- if (c == '-')
- {
- negative = 1;
- c = (unsigned char) *++str;
- }
- /* Default base to decimal. */
- if (base == 0)
- base = 10;
- exp_base = base;
- if (base < 0)
- {
- exp_base = 10;
- base = -base;
- }
- digit_value = digit_value_tab;
- if (base > 36)
- {
- /* For bases > 36, use the collating sequence
- 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz. */
- digit_value += 224;
- if (base > 62)
- return -1; /* too large base */
- }
- /* Require at least one digit, possibly after an initial decimal point. */
- if (digit_value[c] >= (base == 0 ? 10 : base))
- {
- /* not a digit, must be a decimal point */
- for (i = 0; i < pointlen; i++)
- if (str[i] != point[i])
- return -1;
- if (digit_value[(unsigned char) str[pointlen]] >= (base == 0 ? 10 : base))
- return -1;
- }
- /* Locate exponent part of the input. Look from the right of the string,
- since the exponent is usually a lot shorter than the mantissa. */
- expptr = NULL;
- str_size = strlen (str);
- for (i = str_size - 1; i > 0; i--)
- {
- c = (unsigned char) str[i];
- if (c == '@' || (base <= 10 && (c == 'e' || c == 'E')))
- {
- expptr = str + i + 1;
- str_size = i;
- break;
- }
- }
- TMP_MARK;
- s = begs = (char *) TMP_ALLOC (str_size + 1);
- /* Loop through mantissa, converting it from ASCII to raw byte values. */
- for (i = 0; i < str_size; i++)
- {
- c = (unsigned char) *str;
- if (!isspace (c))
- {
- int dig;
- for (j = 0; j < pointlen; j++)
- if (str[j] != point[j])
- goto not_point;
- if (1)
- {
- if (dotpos != 0)
- {
- /* already saw a decimal point, another is invalid */
- TMP_FREE;
- return -1;
- }
- dotpos = s;
- str += pointlen - 1;
- i += pointlen - 1;
- }
- else
- {
- not_point:
- dig = digit_value[c];
- if (dig >= base)
- {
- TMP_FREE;
- return -1;
- }
- *s++ = dig;
- }
- }
- c = (unsigned char) *++str;
- }
- str_size = s - begs;
- {
- long exp_in_base;
- mp_size_t ra, ma, rn, mn;
- int cnt;
- mp_ptr mp, tp, rp;
- mp_exp_t exp_in_limbs;
- mp_size_t prec = PREC(x) + 1;
- int divflag;
- mp_size_t madj, radj;
- #if 0
- size_t n_chars_needed;
- /* This breaks things like 0.000...0001. To safely ignore superfluous
- digits, we need to skip over leading zeros. */
- /* Just consider the relevant leading digits of the mantissa. */
- n_chars_needed = 2 + (size_t)
- (((size_t) prec * GMP_NUMB_BITS) * mp_bases[base].chars_per_bit_exactly);
- if (str_size > n_chars_needed)
- str_size = n_chars_needed;
- #endif
- ma = 2 + (mp_size_t)
- (str_size / (GMP_NUMB_BITS * mp_bases[base].chars_per_bit_exactly));
- mp = TMP_ALLOC_LIMBS (ma);
- mn = mpn_set_str (mp, (unsigned char *) begs, str_size, base);
- if (mn == 0)
- {
- SIZ(x) = 0;
- EXP(x) = 0;
- TMP_FREE;
- return 0;
- }
- madj = 0;
- /* Ignore excess limbs in MP,MSIZE. */
- if (mn > prec)
- {
- madj = mn - prec;
- mp += mn - prec;
- mn = prec;
- }
- if (expptr != 0)
- {
- /* Scan and convert the exponent, in base exp_base. */
- long dig, minus, plusminus;
- c = (unsigned char) *expptr;
- minus = -(long) (c == '-');
- plusminus = minus | -(long) (c == '+');
- expptr -= plusminus; /* conditional increment */
- c = (unsigned char) *expptr++;
- dig = digit_value[c];
- if (dig >= exp_base)
- {
- TMP_FREE;
- return -1;
- }
- exp_in_base = dig;
- c = (unsigned char) *expptr++;
- dig = digit_value[c];
- while (dig < exp_base)
- {
- exp_in_base = exp_in_base * exp_base;
- exp_in_base += dig;
- c = (unsigned char) *expptr++;
- dig = digit_value[c];
- }
- exp_in_base = (exp_in_base ^ minus) - minus; /* conditional negation */
- }
- else
- exp_in_base = 0;
- if (dotpos != 0)
- exp_in_base -= s - dotpos;
- divflag = exp_in_base < 0;
- exp_in_base = ABS (exp_in_base);
- if (exp_in_base == 0)
- {
- MPN_COPY (PTR(x), mp, mn);
- SIZ(x) = negative ? -mn : mn;
- EXP(x) = mn + madj;
- TMP_FREE;
- return 0;
- }
- ra = 2 * (prec + 1);
- rp = TMP_ALLOC_LIMBS (ra);
- tp = TMP_ALLOC_LIMBS (ra);
- rn = mpn_pow_1_highpart (rp, &radj, (mp_limb_t) base, exp_in_base, prec, tp);
- if (divflag)
- {
- #if 0
- /* FIXME: Should use mpn_tdiv here. */
- mpn_tdiv_qr (qp, mp, 0L, mp, mn, rp, rn);
- #else
- mp_ptr qp;
- mp_limb_t qlimb;
- if (mn < rn)
- {
- /* Pad out MP,MSIZE for current divrem semantics. */
- mp_ptr tmp = TMP_ALLOC_LIMBS (rn + 1);
- MPN_ZERO (tmp, rn - mn);
- MPN_COPY (tmp + rn - mn, mp, mn);
- mp = tmp;
- madj -= rn - mn;
- mn = rn;
- }
- if ((rp[rn - 1] & GMP_NUMB_HIGHBIT) == 0)
- {
- mp_limb_t cy;
- count_leading_zeros (cnt, rp[rn - 1]);
- cnt -= GMP_NAIL_BITS;
- mpn_lshift (rp, rp, rn, cnt);
- cy = mpn_lshift (mp, mp, mn, cnt);
- if (cy)
- mp[mn++] = cy;
- }
- qp = TMP_ALLOC_LIMBS (prec + 1);
- qlimb = mpn_divrem (qp, prec - (mn - rn), mp, mn, rp, rn);
- tp = qp;
- exp_in_limbs = qlimb + (mn - rn) + (madj - radj);
- rn = prec;
- if (qlimb != 0)
- {
- tp[prec] = qlimb;
- /* Skip the least significant limb not to overrun the destination
- variable. */
- tp++;
- }
- #endif
- }
- else
- {
- tp = TMP_ALLOC_LIMBS (rn + mn);
- if (rn > mn)
- mpn_mul (tp, rp, rn, mp, mn);
- else
- mpn_mul (tp, mp, mn, rp, rn);
- rn += mn;
- rn -= tp[rn - 1] == 0;
- exp_in_limbs = rn + madj + radj;
- if (rn > prec)
- {
- tp += rn - prec;
- rn = prec;
- exp_in_limbs += 0;
- }
- }
- MPN_COPY (PTR(x), tp, rn);
- SIZ(x) = negative ? -rn : rn;
- EXP(x) = exp_in_limbs;
- TMP_FREE;
- return 0;
- }
- }