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217d85b9c8
* stdlib/strtod.c (STRTOF): Use extra macro to make STRTOF's #defn
a weak symbol instead of literal "STRTOF".
* locale/setlocale.c: Work around ld bug: don't weakify refs to
_nl_{current,C}_*.
1110 lines
30 KiB
C
1110 lines
30 KiB
C
/* Read decimal floating point numbers.
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Copyright (C) 1995 Free Software Foundation, Inc.
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Contributed by Ulrich Drepper.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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/* Configuration part. These macros are defined by `strtold.c' and `strtof.c'
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to produce the `long double' and `float' versions of the reader. */
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#ifndef FLOAT
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#define FLOAT double
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#define FLT DBL
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#define STRTOF strtod
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#define MPN2FLOAT __mpn_construct_double
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#define FLOAT_HUGE_VAL HUGE_VAL
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#endif
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/* End of configuration part. */
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#include <ctype.h>
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#include <errno.h>
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#include <float.h>
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#include "../locale/localeinfo.h"
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#include <math.h>
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#include <stdlib.h>
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#include "gmp.h"
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#include "gmp-impl.h"
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#include <gmp-mparam.h>
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#include "longlong.h"
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#include "fpioconst.h"
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#define NDEBUG 1
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#include <assert.h>
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/* Constants we need from float.h; select the set for the FLOAT precision. */
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#define MANT_DIG PASTE(FLT,_MANT_DIG)
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#define DIG PASTE(FLT,_DIG)
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#define MAX_EXP PASTE(FLT,_MAX_EXP)
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#define MIN_EXP PASTE(FLT,_MIN_EXP)
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#define MAX_10_EXP PASTE(FLT,_MAX_10_EXP)
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#define MIN_10_EXP PASTE(FLT,_MIN_10_EXP)
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/* Extra macros required to get FLT expanded before the pasting. */
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#define PASTE(a,b) PASTE1(a,b)
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#define PASTE1(a,b) a##b
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/* Function to construct a floating point number from an MP integer
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containing the fraction bits, a base 2 exponent, and a sign flag. */
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extern FLOAT MPN2FLOAT (mp_srcptr mpn, int exponent, int negative);
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/* Definitions according to limb size used. */
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#if BITS_PER_MP_LIMB == 32
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# define MAX_DIG_PER_LIMB 9
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# define MAX_FAC_PER_LIMB 1000000000L
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#elif BITS_PER_MP_LIMB == 64
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# define MAX_DIG_PER_LIMB 19
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# define MAX_FAC_PER_LIMB 10000000000000000000L
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#else
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# error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
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#endif
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/* Local data structure. */
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static const mp_limb _tens_in_limb[MAX_DIG_PER_LIMB + 1] =
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{ 0, 10, 100,
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1000, 10000, 100000,
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1000000, 10000000, 100000000,
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1000000000
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#if BITS_PER_MP_LIMB > 32
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, 10000000000, 100000000000,
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1000000000000, 10000000000000, 100000000000000,
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1000000000000000, 10000000000000000, 100000000000000000,
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1000000000000000000, 10000000000000000000
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#endif
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#if BITS_PER_MP_LIMB > 64
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#error "Need to expand tens_in_limb table to" MAX_DIG_PER_LIMB
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#endif
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};
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#ifndef howmany
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#define howmany(x,y) (((x)+((y)-1))/(y))
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#endif
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#define SWAP(x, y) ({ typeof(x) _tmp = x; x = y; y = _tmp; })
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#define NDIG (MAX_10_EXP - MIN_10_EXP + 2 * MANT_DIG)
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#define RETURN_LIMB_SIZE howmany (MANT_DIG, BITS_PER_MP_LIMB)
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#define RETURN(val,end) \
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do { if (endptr != 0) *endptr = (char *) (end); return val; } while (0)
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/* Maximum size necessary for mpn integers to hold floating point numbers. */
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#define MPNSIZE (howmany (MAX_EXP + 2 * MANT_DIG, BITS_PER_MP_LIMB) \
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+ 2)
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/* Declare an mpn integer variable that big. */
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#define MPN_VAR(name) mp_limb name[MPNSIZE]; mp_size_t name##size
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/* Copy an mpn integer value. */
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#define MPN_ASSIGN(dst, src) \
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memcpy (dst, src, (dst##size = src##size) * sizeof (mp_limb))
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/* Return a floating point number of the needed type according to the given
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multi-precision number after possible rounding. */
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static inline FLOAT
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round_and_return (mp_limb *retval, int exponent, int negative,
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mp_limb round_limb, mp_size_t round_bit, int more_bits)
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{
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if (exponent < MIN_EXP - 1)
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{
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mp_size_t shift = MIN_EXP - 1 - exponent;
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if (shift > MANT_DIG)
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{
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errno = EDOM;
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return 0.0;
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}
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more_bits |= (round_limb & ((1 << round_bit) - 1)) != 0;
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if (shift == MANT_DIG)
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/* This is a special case to handle the very seldom case where
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the mantissa will be empty after the shift. */
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{
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int i;
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round_limb = retval[RETURN_LIMB_SIZE - 1];
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round_bit = BITS_PER_MP_LIMB - 1;
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for (i = 0; i < RETURN_LIMB_SIZE; ++i)
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more_bits |= retval[i] != 0;
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MPN_ZERO (retval, RETURN_LIMB_SIZE);
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}
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else if (shift >= BITS_PER_MP_LIMB)
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{
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int i;
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round_limb = retval[(shift - 1) / BITS_PER_MP_LIMB];
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round_bit = (shift - 1) % BITS_PER_MP_LIMB;
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for (i = 0; i < (shift - 1) / BITS_PER_MP_LIMB; ++i)
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more_bits |= retval[i] != 0;
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more_bits |= (round_limb & ((1 << round_bit) - 1)) != 0;
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(void) __mpn_rshift (retval, &retval[shift / BITS_PER_MP_LIMB],
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RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB),
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shift % BITS_PER_MP_LIMB);
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MPN_ZERO (&retval[RETURN_LIMB_SIZE - (shift / BITS_PER_MP_LIMB)],
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shift / BITS_PER_MP_LIMB);
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}
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else if (shift > 0)
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{
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round_limb = retval[0];
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round_bit = shift - 1;
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(void) __mpn_rshift (retval, retval, RETURN_LIMB_SIZE, shift);
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}
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exponent = MIN_EXP - 2;
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}
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if ((round_limb & (1 << round_bit)) != 0
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&& (more_bits || (retval[0] & 1) != 0
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|| (round_limb & ((1 << round_bit) - 1)) != 0))
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{
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mp_limb cy = __mpn_add_1 (retval, retval, RETURN_LIMB_SIZE, 1);
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if (((MANT_DIG % BITS_PER_MP_LIMB) == 0 && cy) ||
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((MANT_DIG % BITS_PER_MP_LIMB) != 0 &&
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(retval[RETURN_LIMB_SIZE - 1]
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& (1 << (MANT_DIG % BITS_PER_MP_LIMB))) != 0))
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{
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++exponent;
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(void) __mpn_rshift (retval, retval, RETURN_LIMB_SIZE, 1);
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retval[RETURN_LIMB_SIZE - 1] |= 1 << ((MANT_DIG - 1)
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% BITS_PER_MP_LIMB);
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}
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else if (exponent == MIN_EXP - 2
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&& (retval[RETURN_LIMB_SIZE - 1]
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& (1 << ((MANT_DIG - 1) % BITS_PER_MP_LIMB))) != 0)
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/* The number was denormalized but now normalized. */
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exponent = MIN_EXP - 1;
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}
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if (exponent > MAX_EXP)
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return negative ? -FLOAT_HUGE_VAL : FLOAT_HUGE_VAL;
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return MPN2FLOAT (retval, exponent, negative);
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}
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/* Read a multi-precision integer starting at STR with exactly DIGCNT digits
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into N. Return the size of the number limbs in NSIZE at the first
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character od the string that is not part of the integer as the function
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value. If the EXPONENT is small enough to be taken as an additional
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factor for the resulting number (see code) multiply by it. */
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static inline const char *
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str_to_mpn (const char *str, int digcnt, mp_limb *n, mp_size_t *nsize,
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int *exponent)
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{
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/* Number of digits for actual limb. */
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int cnt = 0;
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mp_limb low = 0;
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mp_limb base;
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*nsize = 0;
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assert (digcnt > 0);
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do
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{
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if (cnt == MAX_DIG_PER_LIMB)
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{
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if (*nsize == 0)
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n[0] = low;
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else
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{
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mp_limb cy;
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cy = __mpn_mul_1 (n, n, *nsize, MAX_FAC_PER_LIMB);
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cy += __mpn_add_1 (n, n, *nsize, low);
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if (cy != 0)
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n[*nsize] = cy;
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}
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++(*nsize);
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cnt = 0;
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low = 0;
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}
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/* There might be thousands separators or radix characters in the string.
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But these all can be ignored because we know the format of the number
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is correct and we have an exact number of characters to read. */
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while (!isdigit (*str))
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++str;
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low = low * 10 + *str++ - '0';
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++cnt;
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}
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while (--digcnt > 0);
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if (*exponent > 0 && cnt + *exponent <= MAX_DIG_PER_LIMB)
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{
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low *= _tens_in_limb[*exponent];
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base = _tens_in_limb[cnt + *exponent];
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*exponent = 0;
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}
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else
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base = _tens_in_limb[cnt];
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if (*nsize == 0)
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{
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n[0] = low;
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*nsize = 1;
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}
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else
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{
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mp_limb cy;
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cy = __mpn_mul_1 (n, n, *nsize, base);
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cy += __mpn_add_1 (n, n, *nsize, low);
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if (cy != 0)
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n[(*nsize)++] = cy;
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}
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return str;
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}
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/* Shift {PTR, SIZE} COUNT bits to the left, and fill the vacated bits
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with the COUNT most significant bits of LIMB.
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Tege doesn't like this function so I have to write it here myself. :)
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--drepper */
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static inline void
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__mpn_lshift_1 (mp_limb *ptr, mp_size_t size, unsigned int count, mp_limb limb)
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{
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if (count == BITS_PER_MP_LIMB)
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{
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/* Optimize the case of shifting by exactly a word:
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just copy words, with no actual bit-shifting. */
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mp_size_t i;
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for (i = size - 1; i > 0; --i)
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ptr[i] = ptr[i - 1];
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ptr[0] = limb;
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}
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else
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{
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(void) __mpn_lshift (ptr, ptr, size, count);
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ptr[0] |= limb >> (BITS_PER_MP_LIMB - count);
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}
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}
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#define INTERNAL(x) INTERNAL1(x)
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#define INTERNAL1(x) __##x##_internal
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/* This file defines a function to check for correct grouping. */
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#include "grouping.h"
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/* Return a floating point number with the value of the given string NPTR.
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Set *ENDPTR to the character after the last used one. If the number is
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smaller than the smallest representable number, set `errno' to ERANGE and
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return 0.0. If the number is too big to be represented, set `errno' to
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ERANGE and return HUGE_VAL with the approriate sign. */
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FLOAT
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INTERNAL (STRTOF) (nptr, endptr, group)
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const char *nptr;
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char **endptr;
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int group;
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{
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int negative; /* The sign of the number. */
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MPN_VAR (num); /* MP representation of the number. */
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int exponent; /* Exponent of the number. */
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/* When we have to compute fractional digits we form a fraction with a
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second multi-precision number (and we sometimes need a second for
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temporary results). */
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MPN_VAR (den);
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/* Representation for the return value. */
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mp_limb retval[RETURN_LIMB_SIZE];
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/* Number of bits currently in result value. */
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int bits;
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/* Running pointer after the last character processed in the string. */
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const char *cp, *tp;
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/* Start of significant part of the number. */
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const char *startp, *start_of_digits;
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/* Points at the character following the integer and fractional digits. */
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const char *expp;
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/* Total number of digit and number of digits in integer part. */
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int dig_no, int_no, lead_zero;
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/* Contains the last character read. */
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char c;
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/* The radix character of the current locale. */
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wchar_t decimal;
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/* The thousands character of the current locale. */
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wchar_t thousands;
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/* The numeric grouping specification of the current locale,
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in the format described in <locale.h>. */
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const char *grouping;
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if (group)
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{
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grouping = _NL_CURRENT (LC_NUMERIC, GROUPING);
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if (*grouping <= 0 || *grouping == CHAR_MAX)
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grouping = NULL;
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else
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{
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/* Figure out the thousands separator character. */
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if (mbtowc (&thousands, _NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP),
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strlen (_NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP))) <= 0)
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thousands = (wchar_t) *_NL_CURRENT (LC_NUMERIC, THOUSANDS_SEP);
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if (thousands == L'\0')
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grouping = NULL;
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}
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}
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else
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grouping = NULL;
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/* Find the locale's decimal point character. */
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if (mbtowc (&decimal, _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT),
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strlen (_NL_CURRENT (LC_NUMERIC, DECIMAL_POINT))) <= 0)
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decimal = (wchar_t) *_NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
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/* Prepare number representation. */
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exponent = 0;
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negative = 0;
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bits = 0;
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/* Parse string to get maximal legal prefix. We need the number of
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characters of the interger part, the fractional part and the exponent. */
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cp = nptr - 1;
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/* Ignore leading white space. */
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do
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c = *++cp;
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while (isspace (c));
|
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|
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/* Get sign of the result. */
|
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if (c == '-')
|
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{
|
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negative = 1;
|
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c = *++cp;
|
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}
|
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else if (c == '+')
|
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c = *++cp;
|
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|
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/* Return 0.0 if no legal string is found.
|
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No character is used even if a sign was found. */
|
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if (!isdigit (c) && (c != decimal || !isdigit (cp[1])))
|
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RETURN (0.0, nptr);
|
||
|
||
/* Record the start of the digits, in case we will check their grouping. */
|
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start_of_digits = startp = cp;
|
||
|
||
/* Ignore leading zeroes. This helps us to avoid useless computations. */
|
||
while (c == '0' || (thousands != L'\0' && c == thousands))
|
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c = *++cp;
|
||
|
||
/* If no other digit but a '0' is found the result is 0.0.
|
||
Return current read pointer. */
|
||
if (!isdigit (c) && c != decimal)
|
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{
|
||
tp = correctly_grouped_prefix (start_of_digits, cp, thousands, grouping);
|
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/* If TP is at the start of the digits, there was no correctly
|
||
grouped prefix of the string; so no number found. */
|
||
RETURN (0.0, tp == start_of_digits ? nptr : tp);
|
||
}
|
||
|
||
/* Remember first significant digit and read following characters until the
|
||
decimal point, exponent character or any non-FP number character. */
|
||
startp = cp;
|
||
dig_no = 0;
|
||
while (dig_no < NDIG ||
|
||
/* If parsing grouping info, keep going past useful digits
|
||
so we can check all the grouping separators. */
|
||
grouping)
|
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{
|
||
if (isdigit (c))
|
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++dig_no;
|
||
else if (thousands == L'\0' || c != thousands)
|
||
/* Not a digit or separator: end of the integer part. */
|
||
break;
|
||
c = *++cp;
|
||
}
|
||
|
||
if (grouping && dig_no > 0)
|
||
{
|
||
/* Check the grouping of the digits. */
|
||
tp = correctly_grouped_prefix (start_of_digits, cp, thousands, grouping);
|
||
if (cp != tp)
|
||
{
|
||
/* Less than the entire string was correctly grouped. */
|
||
|
||
if (tp == start_of_digits)
|
||
/* No valid group of numbers at all: no valid number. */
|
||
RETURN (0.0, nptr);
|
||
|
||
if (tp < startp)
|
||
/* The number is validly grouped, but consists
|
||
only of zeroes. The whole value is zero. */
|
||
RETURN (0.0, tp);
|
||
|
||
/* Recompute DIG_NO so we won't read more digits than
|
||
are properly grouped. */
|
||
cp = tp;
|
||
dig_no = 0;
|
||
for (tp = startp; tp < cp; ++tp)
|
||
if (isdigit (*tp))
|
||
++dig_no;
|
||
|
||
int_no = dig_no;
|
||
lead_zero = 0;
|
||
|
||
goto number_parsed;
|
||
}
|
||
}
|
||
|
||
if (dig_no >= NDIG)
|
||
/* Too many digits to be representable. Assigning this to EXPONENT
|
||
allows us to read the full number but return HUGE_VAL after parsing. */
|
||
exponent = MAX_10_EXP;
|
||
|
||
/* We have the number digits in the integer part. Whether these are all or
|
||
any is really a fractional digit will be decided later. */
|
||
int_no = dig_no;
|
||
lead_zero = int_no == 0 ? -1 : 0;
|
||
|
||
/* Read the fractional digits. */
|
||
if (c == decimal)
|
||
{
|
||
if (isdigit (cp[1]))
|
||
{
|
||
c = *++cp;
|
||
do
|
||
{
|
||
if (c != '0' && lead_zero == -1)
|
||
lead_zero = dig_no - int_no;
|
||
++dig_no;
|
||
c = *++cp;
|
||
}
|
||
while (isdigit (c));
|
||
}
|
||
}
|
||
|
||
/* Remember start of exponent (if any). */
|
||
expp = cp;
|
||
|
||
/* Read exponent. */
|
||
if (tolower (c) == 'e')
|
||
{
|
||
int exp_negative = 0;
|
||
|
||
c = *++cp;
|
||
if (c == '-')
|
||
{
|
||
exp_negative = 1;
|
||
c = *++cp;
|
||
}
|
||
else if (c == '+')
|
||
c = *++cp;
|
||
|
||
if (isdigit (c))
|
||
{
|
||
do
|
||
{
|
||
if ((!exp_negative && exponent * 10 + int_no > MAX_10_EXP)
|
||
|| (exp_negative
|
||
&& exponent * 10 + int_no > -MIN_10_EXP + MANT_DIG))
|
||
/* The exponent is too large/small to represent a valid
|
||
number. */
|
||
{
|
||
FLOAT retval;
|
||
|
||
/* Overflow or underflow. */
|
||
errno = ERANGE;
|
||
retval = (exp_negative ? 0.0 :
|
||
negative ? -FLOAT_HUGE_VAL : FLOAT_HUGE_VAL);
|
||
|
||
/* Accept all following digits as part of the exponent. */
|
||
do
|
||
++cp;
|
||
while (isdigit (*cp));
|
||
|
||
RETURN (retval, cp);
|
||
/* NOTREACHED */
|
||
}
|
||
|
||
exponent *= 10;
|
||
exponent += c - '0';
|
||
c = *++cp;
|
||
}
|
||
while (isdigit (c));
|
||
}
|
||
else
|
||
cp = expp;
|
||
|
||
if (exp_negative)
|
||
exponent = -exponent;
|
||
}
|
||
|
||
/* We don't want to have to work with trailing zeroes after the radix. */
|
||
if (dig_no > int_no)
|
||
{
|
||
while (expp[-1] == '0')
|
||
{
|
||
--expp;
|
||
--dig_no;
|
||
}
|
||
assert (dig_no >= int_no);
|
||
}
|
||
|
||
number_parsed:
|
||
|
||
/* The whole string is parsed. Store the address of the next character. */
|
||
if (endptr)
|
||
*endptr = (char *) cp;
|
||
|
||
if (dig_no == 0)
|
||
return 0.0;
|
||
|
||
/* Now we have the number of digits in total and the integer digits as well
|
||
as the exponent and its sign. We can decide whether the read digits are
|
||
really integer digits or belong to the fractional part; i.e. we normalize
|
||
123e-2 to 1.23. */
|
||
{
|
||
register int incr = exponent < 0 ? MAX (-int_no, exponent)
|
||
: MIN (dig_no - int_no, exponent);
|
||
int_no += incr;
|
||
exponent -= incr;
|
||
}
|
||
|
||
if (int_no + exponent > MAX_10_EXP + 1)
|
||
{
|
||
errno = ERANGE;
|
||
return negative ? -FLOAT_HUGE_VAL : FLOAT_HUGE_VAL;
|
||
}
|
||
|
||
if (exponent - MAX(0, lead_zero) < MIN_10_EXP - (DIG + 1))
|
||
{
|
||
errno = ERANGE;
|
||
return 0.0;
|
||
}
|
||
|
||
if (int_no > 0)
|
||
{
|
||
/* Read the integer part as a multi-precision number to NUM. */
|
||
startp = str_to_mpn (startp, int_no, num, &numsize, &exponent);
|
||
|
||
if (exponent > 0)
|
||
{
|
||
/* We now multiply the gained number by the given power of ten. */
|
||
mp_limb *psrc = num;
|
||
mp_limb *pdest = den;
|
||
int expbit = 1;
|
||
const struct mp_power *ttab = &_fpioconst_pow10[0];
|
||
|
||
do
|
||
{
|
||
if ((exponent & expbit) != 0)
|
||
{
|
||
mp_limb cy;
|
||
exponent ^= expbit;
|
||
|
||
/* FIXME: not the whole multiplication has to be done.
|
||
If we have the needed number of bits we only need the
|
||
information whether more non-zero bits follow. */
|
||
if (numsize >= ttab->arraysize - 2)
|
||
cy = __mpn_mul (pdest, psrc, numsize,
|
||
&ttab->array[2], ttab->arraysize - 2);
|
||
else
|
||
cy = __mpn_mul (pdest, &ttab->array[2],
|
||
ttab->arraysize - 2,
|
||
psrc, numsize);
|
||
numsize += ttab->arraysize - 2;
|
||
if (cy == 0)
|
||
--numsize;
|
||
SWAP (psrc, pdest);
|
||
}
|
||
expbit <<= 1;
|
||
++ttab;
|
||
}
|
||
while (exponent != 0);
|
||
|
||
if (psrc == den)
|
||
memcpy (num, den, numsize * sizeof (mp_limb));
|
||
}
|
||
|
||
/* Determine how many bits of the result we already have. */
|
||
count_leading_zeros (bits, num[numsize - 1]);
|
||
bits = numsize * BITS_PER_MP_LIMB - bits;
|
||
|
||
/* Now we know the exponent of the number in base two.
|
||
Check it against the maximum possible exponent. */
|
||
if (bits > MAX_EXP)
|
||
{
|
||
errno = ERANGE;
|
||
return negative ? -FLOAT_HUGE_VAL : FLOAT_HUGE_VAL;
|
||
}
|
||
|
||
/* We have already the first BITS bits of the result. Together with
|
||
the information whether more non-zero bits follow this is enough
|
||
to determine the result. */
|
||
if (bits > MANT_DIG)
|
||
{
|
||
int i;
|
||
const mp_size_t least_idx = (bits - MANT_DIG) / BITS_PER_MP_LIMB;
|
||
const mp_size_t least_bit = (bits - MANT_DIG) % BITS_PER_MP_LIMB;
|
||
const mp_size_t round_idx = least_bit == 0 ? least_idx - 1
|
||
: least_idx;
|
||
const mp_size_t round_bit = least_bit == 0 ? BITS_PER_MP_LIMB - 1
|
||
: least_bit - 1;
|
||
|
||
if (least_bit == 0)
|
||
memcpy (retval, &num[least_idx],
|
||
RETURN_LIMB_SIZE * sizeof (mp_limb));
|
||
else
|
||
{
|
||
for (i = least_idx; i < numsize - 1; ++i)
|
||
retval[i - least_idx] = (num[i] >> least_bit)
|
||
| (num[i + 1]
|
||
<< (BITS_PER_MP_LIMB - least_bit));
|
||
if (i - least_idx < RETURN_LIMB_SIZE)
|
||
retval[RETURN_LIMB_SIZE - 1] = num[i] >> least_bit;
|
||
}
|
||
|
||
/* Check whether any limb beside the ones in RETVAL are non-zero. */
|
||
for (i = 0; num[i] == 0; ++i)
|
||
;
|
||
|
||
return round_and_return (retval, bits - 1, negative,
|
||
num[round_idx], round_bit,
|
||
int_no < dig_no || i < round_idx);
|
||
/* NOTREACHED */
|
||
}
|
||
else if (dig_no == int_no)
|
||
{
|
||
const mp_size_t target_bit = (MANT_DIG - 1) % BITS_PER_MP_LIMB;
|
||
const mp_size_t is_bit = (bits - 1) % BITS_PER_MP_LIMB;
|
||
|
||
if (target_bit == is_bit)
|
||
{
|
||
memcpy (&retval[RETURN_LIMB_SIZE - numsize], num,
|
||
numsize * sizeof (mp_limb));
|
||
/* FIXME: the following loop can be avoided if we assume a
|
||
maximal MANT_DIG value. */
|
||
MPN_ZERO (retval, RETURN_LIMB_SIZE - numsize);
|
||
}
|
||
else if (target_bit > is_bit)
|
||
{
|
||
(void) __mpn_lshift (&retval[RETURN_LIMB_SIZE - numsize],
|
||
num, numsize, target_bit - is_bit);
|
||
/* FIXME: the following loop can be avoided if we assume a
|
||
maximal MANT_DIG value. */
|
||
MPN_ZERO (retval, RETURN_LIMB_SIZE - numsize);
|
||
}
|
||
else
|
||
{
|
||
mp_limb cy;
|
||
assert (numsize < RETURN_LIMB_SIZE);
|
||
|
||
cy = __mpn_rshift (&retval[RETURN_LIMB_SIZE - numsize],
|
||
num, numsize, is_bit - target_bit);
|
||
retval[RETURN_LIMB_SIZE - numsize - 1] = cy;
|
||
/* FIXME: the following loop can be avoided if we assume a
|
||
maximal MANT_DIG value. */
|
||
MPN_ZERO (retval, RETURN_LIMB_SIZE - numsize - 1);
|
||
}
|
||
|
||
return round_and_return (retval, bits - 1, negative, 0, 0, 0);
|
||
/* NOTREACHED */
|
||
}
|
||
|
||
/* Store the bits we already have. */
|
||
memcpy (retval, num, numsize * sizeof (mp_limb));
|
||
#if RETURN_LIMB_SIZE > 1
|
||
if (numsize < RETURN_LIMB_SIZE)
|
||
retval[numsize] = 0;
|
||
#endif
|
||
}
|
||
|
||
/* We have to compute at least some of the fractional digits. */
|
||
{
|
||
/* We construct a fraction and the result of the division gives us
|
||
the needed digits. The denominator is 1.0 multiplied by the
|
||
exponent of the lowest digit; i.e. 0.123 gives 123 / 1000 and
|
||
123e6 gives 123 / 1000000. */
|
||
|
||
int expbit;
|
||
int cnt;
|
||
int neg_exp;
|
||
int more_bits;
|
||
mp_limb cy;
|
||
mp_limb *psrc = den;
|
||
mp_limb *pdest = num;
|
||
const struct mp_power *ttab = &_fpioconst_pow10[0];
|
||
|
||
assert (dig_no > int_no && exponent <= 0);
|
||
|
||
|
||
/* For the fractional part we need not process too much digits. One
|
||
decimal digits gives us log_2(10) ~ 3.32 bits. If we now compute
|
||
ceil(BITS / 3) =: N
|
||
digits we should have enough bits for the result. The remaining
|
||
decimal digits give us the information that more bits are following.
|
||
This can be used while rounding. (One added as a safety margin.) */
|
||
if (dig_no - int_no > (MANT_DIG - bits + 2) / 3 + 1)
|
||
{
|
||
dig_no = int_no + (MANT_DIG - bits + 2) / 3 + 1;
|
||
more_bits = 1;
|
||
}
|
||
else
|
||
more_bits = 0;
|
||
|
||
neg_exp = dig_no - int_no - exponent;
|
||
|
||
/* Construct the denominator. */
|
||
densize = 0;
|
||
expbit = 1;
|
||
do
|
||
{
|
||
if ((neg_exp & expbit) != 0)
|
||
{
|
||
mp_limb cy;
|
||
neg_exp ^= expbit;
|
||
|
||
if (densize == 0)
|
||
memcpy (psrc, &ttab->array[2],
|
||
(densize = ttab->arraysize - 2) * sizeof (mp_limb));
|
||
else
|
||
{
|
||
cy = __mpn_mul (pdest, &ttab->array[2], ttab->arraysize - 2,
|
||
psrc, densize);
|
||
densize += ttab->arraysize - 2;
|
||
if (cy == 0)
|
||
--densize;
|
||
SWAP (psrc, pdest);
|
||
}
|
||
}
|
||
expbit <<= 1;
|
||
++ttab;
|
||
}
|
||
while (neg_exp != 0);
|
||
|
||
if (psrc == num)
|
||
memcpy (den, num, densize * sizeof (mp_limb));
|
||
|
||
/* Read the fractional digits from the string. */
|
||
(void) str_to_mpn (startp, dig_no - int_no, num, &numsize, &exponent);
|
||
|
||
|
||
/* We now have to shift both numbers so that the highest bit in the
|
||
denominator is set. In the same process we copy the numerator to
|
||
a high place in the array so that the division constructs the wanted
|
||
digits. This is done by a "quasi fix point" number representation.
|
||
|
||
num: ddddddddddd . 0000000000000000000000
|
||
|--- m ---|
|
||
den: ddddddddddd n >= m
|
||
|--- n ---|
|
||
*/
|
||
|
||
count_leading_zeros (cnt, den[densize - 1]);
|
||
|
||
(void) __mpn_lshift (den, den, densize, cnt);
|
||
cy = __mpn_lshift (num, num, numsize, cnt);
|
||
if (cy != 0)
|
||
num[numsize++] = cy;
|
||
|
||
/* Now we are ready for the division. But it is not necessary to
|
||
do a full multi-precision division because we only need a small
|
||
number of bits for the result. So we do not use __mpn_divmod
|
||
here but instead do the division here by hand and stop whenever
|
||
the needed number of bits is reached. The code itself comes
|
||
from the GNU MP Library by Torbj\"orn Granlund. */
|
||
|
||
exponent = bits;
|
||
|
||
switch (densize)
|
||
{
|
||
case 1:
|
||
{
|
||
mp_limb d, n, quot;
|
||
int used = 0;
|
||
|
||
n = num[0];
|
||
d = den[0];
|
||
assert (numsize == 1 && n < d);
|
||
|
||
do
|
||
{
|
||
udiv_qrnnd (quot, n, n, 0, d);
|
||
|
||
#define got_limb \
|
||
if (bits == 0) \
|
||
{ \
|
||
register int cnt; \
|
||
if (quot == 0) \
|
||
cnt = BITS_PER_MP_LIMB; \
|
||
else \
|
||
count_leading_zeros (cnt, quot); \
|
||
exponent -= cnt; \
|
||
if (BITS_PER_MP_LIMB - cnt > MANT_DIG) \
|
||
{ \
|
||
used = MANT_DIG + cnt; \
|
||
retval[0] = quot >> (BITS_PER_MP_LIMB - used); \
|
||
bits = MANT_DIG + 1; \
|
||
} \
|
||
else \
|
||
{ \
|
||
/* Note that we only clear the second element. */ \
|
||
/* The conditional is determined at compile time. */ \
|
||
if (RETURN_LIMB_SIZE > 1) \
|
||
retval[1] = 0; \
|
||
retval[0] = quot; \
|
||
bits = -cnt; \
|
||
} \
|
||
} \
|
||
else if (bits + BITS_PER_MP_LIMB <= MANT_DIG) \
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE, BITS_PER_MP_LIMB, \
|
||
quot); \
|
||
else \
|
||
{ \
|
||
used = MANT_DIG - bits; \
|
||
if (used > 0) \
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE, used, quot); \
|
||
} \
|
||
bits += BITS_PER_MP_LIMB
|
||
|
||
got_limb;
|
||
}
|
||
while (bits <= MANT_DIG);
|
||
|
||
return round_and_return (retval, exponent - 1, negative,
|
||
quot, BITS_PER_MP_LIMB - 1 - used,
|
||
more_bits || n != 0);
|
||
}
|
||
case 2:
|
||
{
|
||
mp_limb d0, d1, n0, n1;
|
||
mp_limb quot = 0;
|
||
int used = 0;
|
||
|
||
d0 = den[0];
|
||
d1 = den[1];
|
||
|
||
if (numsize < densize)
|
||
{
|
||
if (bits <= 0)
|
||
exponent -= BITS_PER_MP_LIMB;
|
||
else
|
||
{
|
||
if (bits + BITS_PER_MP_LIMB <= MANT_DIG)
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE,
|
||
BITS_PER_MP_LIMB, 0);
|
||
else
|
||
{
|
||
used = MANT_DIG - bits;
|
||
if (used > 0)
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE, used, 0);
|
||
}
|
||
bits += BITS_PER_MP_LIMB;
|
||
}
|
||
n1 = num[0];
|
||
n0 = 0;
|
||
}
|
||
else
|
||
{
|
||
n1 = num[1];
|
||
n0 = num[0];
|
||
}
|
||
|
||
while (bits <= MANT_DIG)
|
||
{
|
||
mp_limb r;
|
||
|
||
if (n1 == d1)
|
||
{
|
||
/* QUOT should be either 111..111 or 111..110. We need
|
||
special treatment of this rare case as normal division
|
||
would give overflow. */
|
||
quot = ~(mp_limb) 0;
|
||
|
||
r = n0 + d1;
|
||
if (r < d1) /* Carry in the addition? */
|
||
{
|
||
add_ssaaaa (n1, n0, r - d0, 0, 0, d0);
|
||
goto have_quot;
|
||
}
|
||
n1 = d0 - (d0 != 0);
|
||
n0 = -d0;
|
||
}
|
||
else
|
||
{
|
||
udiv_qrnnd (quot, r, n1, n0, d1);
|
||
umul_ppmm (n1, n0, d0, quot);
|
||
}
|
||
|
||
q_test:
|
||
if (n1 > r || (n1 == r && n0 > 0))
|
||
{
|
||
/* The estimated QUOT was too large. */
|
||
--quot;
|
||
|
||
sub_ddmmss (n1, n0, n1, n0, 0, d0);
|
||
r += d1;
|
||
if (r >= d1) /* If not carry, test QUOT again. */
|
||
goto q_test;
|
||
}
|
||
sub_ddmmss (n1, n0, r, 0, n1, n0);
|
||
|
||
have_quot:
|
||
got_limb;
|
||
}
|
||
|
||
return round_and_return (retval, exponent - 1, negative,
|
||
quot, BITS_PER_MP_LIMB - 1 - used,
|
||
more_bits || n1 != 0 || n0 != 0);
|
||
}
|
||
default:
|
||
{
|
||
int i;
|
||
mp_limb cy, dX, d1, n0, n1;
|
||
mp_limb quot = 0;
|
||
int used = 0;
|
||
|
||
dX = den[densize - 1];
|
||
d1 = den[densize - 2];
|
||
|
||
/* The division does not work if the upper limb of the two-limb
|
||
numerator is greater than the denominator. */
|
||
if (__mpn_cmp (num, &den[densize - numsize], numsize) > 0)
|
||
num[numsize++] = 0;
|
||
|
||
if (numsize < densize)
|
||
{
|
||
mp_size_t empty = densize - numsize;
|
||
|
||
if (bits <= 0)
|
||
{
|
||
register int i;
|
||
for (i = numsize; i > 0; --i)
|
||
num[i + empty] = num[i - 1];
|
||
MPN_ZERO (num, empty + 1);
|
||
exponent -= empty * BITS_PER_MP_LIMB;
|
||
}
|
||
else
|
||
{
|
||
if (bits + empty * BITS_PER_MP_LIMB <= MANT_DIG)
|
||
{
|
||
/* We make a difference here because the compiler
|
||
cannot optimize the `else' case that good and
|
||
this reflects all currently used FLOAT types
|
||
and GMP implementations. */
|
||
register int i;
|
||
#if RETURN_LIMB_SIZE <= 2
|
||
assert (empty == 1);
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE,
|
||
BITS_PER_MP_LIMB, 0);
|
||
#else
|
||
for (i = RETURN_LIMB_SIZE; i > empty; --i)
|
||
retval[i] = retval[i - empty];
|
||
#endif
|
||
retval[1] = 0;
|
||
for (i = numsize; i > 0; --i)
|
||
num[i + empty] = num[i - 1];
|
||
MPN_ZERO (num, empty + 1);
|
||
}
|
||
else
|
||
{
|
||
used = MANT_DIG - bits;
|
||
if (used >= BITS_PER_MP_LIMB)
|
||
{
|
||
register int i;
|
||
(void) __mpn_lshift (&retval[used
|
||
/ BITS_PER_MP_LIMB],
|
||
retval, RETURN_LIMB_SIZE,
|
||
used % BITS_PER_MP_LIMB);
|
||
for (i = used / BITS_PER_MP_LIMB; i >= 0; --i)
|
||
retval[i] = 0;
|
||
}
|
||
else if (used > 0)
|
||
__mpn_lshift_1 (retval, RETURN_LIMB_SIZE, used, 0);
|
||
}
|
||
bits += empty * BITS_PER_MP_LIMB;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
int i;
|
||
assert (numsize == densize);
|
||
for (i = numsize; i > 0; --i)
|
||
num[i] = num[i - 1];
|
||
}
|
||
|
||
den[densize] = 0;
|
||
n0 = num[densize];
|
||
|
||
while (bits <= MANT_DIG)
|
||
{
|
||
if (n0 == dX)
|
||
/* This might over-estimate QUOT, but it's probably not
|
||
worth the extra code here to find out. */
|
||
quot = ~(mp_limb) 0;
|
||
else
|
||
{
|
||
mp_limb r;
|
||
|
||
udiv_qrnnd (quot, r, n0, num[densize - 1], dX);
|
||
umul_ppmm (n1, n0, d1, quot);
|
||
|
||
while (n1 > r || (n1 == r && n0 > num[densize - 2]))
|
||
{
|
||
--quot;
|
||
r += dX;
|
||
if (r < dX) /* I.e. "carry in previous addition?" */
|
||
break;
|
||
n1 -= n0 < d1;
|
||
n0 -= d1;
|
||
}
|
||
}
|
||
|
||
/* Possible optimization: We already have (q * n0) and (1 * n1)
|
||
after the calculation of QUOT. Taking advantage of this, we
|
||
could make this loop make two iterations less. */
|
||
|
||
cy = __mpn_submul_1 (num, den, densize + 1, quot);
|
||
|
||
if (num[densize] != cy)
|
||
{
|
||
cy = __mpn_add_n (num, num, den, densize);
|
||
assert (cy != 0);
|
||
--quot;
|
||
}
|
||
n0 = num[densize] = num[densize - 1];
|
||
for (i = densize - 1; i > 0; --i)
|
||
num[i] = num[i - 1];
|
||
|
||
got_limb;
|
||
}
|
||
|
||
for (i = densize; num[i] == 0 && i >= 0; --i)
|
||
;
|
||
return round_and_return (retval, exponent - 1, negative,
|
||
quot, BITS_PER_MP_LIMB - 1 - used,
|
||
more_bits || i >= 0);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* NOTREACHED */
|
||
}
|
||
|
||
/* External user entry point. */
|
||
|
||
#define weak_this(x) weak_symbol(x)
|
||
weak_this (STRTOF)
|
||
|
||
FLOAT
|
||
STRTOF (nptr, endptr)
|
||
const char *nptr;
|
||
char **endptr;
|
||
{
|
||
return INTERNAL (STRTOF) (nptr, endptr, 0);
|
||
}
|