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/* mpfr_set_str -- set a floating-point number from a string
Copyright (C) 2000 PolKA project, Inria Lorraine and Loria
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The MPFR 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAS_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "mpfr.h"
int
#if __STDC__
mpfr_set_str(mpfr_ptr x, char *str, int base, mp_rnd_t rnd_mode)
#else
mpfr_set_str(x, str, base, rnd_mode)
mpfr_ptr x;
char *str;
int base;
mp_rnd_t rnd_mode;
#endif
{
char negative = 0, *endptr;
unsigned long k = 0, l, q;
long expn = 0, e;
mpz_t mantissa;
mpfr_t y, z;
mpz_init(mantissa); mpz_set_ui(mantissa, 0);
l = strlen(str);
if (*str == '-') { negative = 1; str++; l--; }
else if (*str == '+') { str++; l--; }
while (*str == '0') { str++; l--; } /* skip initial zeros */
/* allowed characters are '0' to '0'+base-1 if base <= 10,
and '0' to '9' plus 'a' to 'a'+base-11 if 10 < base <= 36 */
while ((isdigit(*str) && *str < '0'+base)
|| (islower(*str) && *str < 'a'+base-10))
{
mpz_mul_ui(mantissa, mantissa, base);
mpz_add_ui(mantissa, mantissa, (isdigit(*str)) ? (*str)-'0'
: (*str)-'a'+10);
str++; l--;
}
/* k is the number of non-zero digits before the decimal point */
if (*str == '.')
{
str++; l--;
while ((isdigit(*str) && *str < '0'+base)
|| (islower(*str) && *str < 'a'+base-10))
{
mpz_mul_ui(mantissa, mantissa, base);
mpz_add_ui(mantissa, mantissa, (isdigit(*str)) ? (*str)-'0'
: (*str)-'a'+10);
str++; l--;
k++;
}
}
if ((base <= 10 && (*str == 'e' || *str == 'E')) || *str == '@')
{
str++; l--;
e = strtol(str, &endptr, 10); /* signed exponent after 'e', 'E' or '@' */
expn = e - k;
if (expn > e)
fprintf(stderr, "Warning: exponent underflow in mpfr_set_str\n");
}
else if (l) {
fprintf(stderr, "Unexpected end of string in mpfr_set_str: %s\n", str);
return -1;
}
else {
expn = -k;
endptr = str;
}
/* the number is mantissa*base^expn */
q = (PREC(x)/BITS_PER_MP_LIMB)*BITS_PER_MP_LIMB;
mpfr_init(y);
mpfr_init(z);
do {
q += BITS_PER_MP_LIMB;
mpfr_set_prec(y, q);
mpfr_set_z(y, mantissa, GMP_RNDN); /* error <= 1/2*ulp(y) */
mpfr_set_prec(z, q);
if (expn>0) {
e = mpfr_ui_pow_ui(z, base, expn, GMP_RNDN);
mpfr_mul(y, y, z, GMP_RNDN);
}
else if (expn<0) {
e = mpfr_ui_pow_ui(z, base, -expn, GMP_RNDN);
mpfr_div(y, y, z, GMP_RNDN);
}
else e=1;
if (negative) mpfr_neg(y, y, GMP_RNDN);
/* now y is an approximation of mantissa*base^expn with error at most
2^e*ulp(y) */
} while (mpfr_can_round(y, q-e, GMP_RNDN, rnd_mode, PREC(x))==0
&& q<=2*PREC(x));
mpfr_set(x, y, rnd_mode);
mpz_clear(mantissa);
mpfr_clear(y);
mpfr_clear(z);
return ((*endptr=='\0') ? 0 : -1);
}
int
#if __STDC__
mpfr_init_set_str(mpfr_ptr x, char *str, int base, mp_rnd_t rnd_mode)
#else
mpfr_init_set_str(x, str, base, rnd_mode)
mpfr_ptr x;
char *str;
int base;
mp_rnd_t rnd_mode;
#endif
{
mpfr_init(x);
return mpfr_set_str(x, str, base, rnd_mode);
}
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