--- /dev/null
+/* mpf_get_str (digit_ptr, exp, base, n_digits, a) -- Convert the floating
+ point number A to a base BASE number and store N_DIGITS raw digits at
+ DIGIT_PTR, and the base BASE exponent in the word pointed to by EXP. For
+ example, the number 3.1416 would be returned as "31416" in DIGIT_PTR and
+ 1 in EXP.
+
+Copyright 1993, 1994, 1995, 1996, 1997, 2000, 2001, 2002, 2003, 2005, 2006 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/. */
+
+#include <stdlib.h> /* for NULL */
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "longlong.h" /* for count_leading_zeros */
+
+/* Could use some more work.
+
+ 1. Allocation is excessive. Try to combine areas. Perhaps use result
+ string area for temp limb space?
+ 2. We generate up to two limbs of extra digits. This is because we don't
+ check the exact number of bits in the input operand, and from that
+ compute an accurate exponent (variable e in the code). It would be
+ cleaner and probably somewhat faster to change this.
+*/
+
+/* 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).
+ Allocation of rp[] and the temporary tp[] should be 2*prec+2 limbs. */
+static mp_size_t
+mpn_pow_1_highpart (mp_ptr rp, mp_size_t *ignp,
+ mp_limb_t base, unsigned long 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;
+
+ if (exp == 0)
+ {
+ rp[0] = 1;
+ *ignp = 0;
+ return 1;
+ }
+
+ 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_n (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)
+ {
+ ASSERT (rn == prec + 1);
+
+ ign += rn - prec;
+ rp += rn - prec;
+ rn = prec;
+ }
+
+ /* With somewhat less than 50% probability, we can skip this copy. */
+ if (passed_rp != rp + off)
+ MPN_COPY_INCR (passed_rp, rp + off, rn);
+ *ignp = ign;
+ return rn;
+}
+
+char *
+mpf_get_str (char *dbuf, mp_exp_t *exp, int base, size_t n_digits, mpf_srcptr u)
+{
+ mp_exp_t ue;
+ mp_size_t n_limbs_needed;
+ size_t max_digits;
+ mp_ptr up, pp, tp;
+ mp_size_t un, pn, tn;
+ unsigned char *tstr;
+ mp_exp_t exp_in_base;
+ size_t n_digits_computed;
+ mp_size_t i;
+ const char *num_to_text;
+ size_t alloc_size = 0;
+ char *dp;
+ TMP_DECL;
+
+ up = PTR(u);
+ un = ABSIZ(u);
+ ue = EXP(u);
+
+ if (base >= 0)
+ {
+ num_to_text = "0123456789abcdefghijklmnopqrstuvwxyz";
+ if (base == 0)
+ base = 10;
+ else if (base > 36)
+ {
+ num_to_text = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+ if (base > 62)
+ return NULL;
+ }
+ }
+ else
+ {
+ base = -base;
+ num_to_text = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ }
+
+ MPF_SIGNIFICANT_DIGITS (max_digits, base, PREC(u));
+ if (n_digits == 0 || n_digits > max_digits)
+ n_digits = max_digits;
+
+ if (dbuf == 0)
+ {
+ /* We didn't get a string from the user. Allocate one (and return
+ a pointer to it) with space for `-' and terminating null. */
+ alloc_size = n_digits + 2;
+ dbuf = (char *) (*__gmp_allocate_func) (n_digits + 2);
+ }
+
+ if (un == 0)
+ {
+ *exp = 0;
+ *dbuf = 0;
+ n_digits = 0;
+ goto done;
+ }
+
+ TMP_MARK;
+
+ /* Allocate temporary digit space. We can't put digits directly in the user
+ area, since we generate more digits than requested. (We allocate
+ 2 * GMP_LIMB_BITS extra bytes because of the digit block nature of the
+ conversion.) */
+ tstr = (unsigned char *) TMP_ALLOC (n_digits + 2 * GMP_LIMB_BITS + 3);
+
+ n_limbs_needed = 2 + ((mp_size_t) (n_digits / mp_bases[base].chars_per_bit_exactly)) / GMP_NUMB_BITS;
+
+ if (ue <= n_limbs_needed)
+ {
+ /* We need to multiply number by base^n to get an n_digits integer part. */
+ mp_size_t n_more_limbs_needed, ign, off;
+ unsigned long e;
+
+ n_more_limbs_needed = n_limbs_needed - ue;
+ e = (unsigned long) n_more_limbs_needed * (GMP_NUMB_BITS * mp_bases[base].chars_per_bit_exactly);
+
+ if (un > n_limbs_needed)
+ {
+ up += un - n_limbs_needed;
+ un = n_limbs_needed;
+ }
+ pp = TMP_ALLOC_LIMBS (2 * n_limbs_needed + 2);
+ tp = TMP_ALLOC_LIMBS (2 * n_limbs_needed + 2);
+
+ pn = mpn_pow_1_highpart (pp, &ign, (mp_limb_t) base, e, n_limbs_needed, tp);
+ if (un > pn)
+ mpn_mul (tp, up, un, pp, pn); /* FIXME: mpn_mul_highpart */
+ else
+ mpn_mul (tp, pp, pn, up, un); /* FIXME: mpn_mul_highpart */
+ tn = un + pn;
+ tn -= tp[tn - 1] == 0;
+ off = un - ue - ign;
+ if (off < 0)
+ {
+ MPN_COPY_DECR (tp - off, tp, tn);
+ MPN_ZERO (tp, -off);
+ tn -= off;
+ off = 0;
+ }
+ n_digits_computed = mpn_get_str (tstr, base, tp + off, tn - off);
+
+ exp_in_base = n_digits_computed - e;
+ }
+ else
+ {
+ /* We need to divide number by base^n to get an n_digits integer part. */
+ mp_size_t n_less_limbs_needed, ign, off, xn;
+ unsigned long e;
+ mp_ptr dummyp, xp;
+
+ n_less_limbs_needed = ue - n_limbs_needed;
+ e = (unsigned long) n_less_limbs_needed * (GMP_NUMB_BITS * mp_bases[base].chars_per_bit_exactly);
+
+ if (un > n_limbs_needed)
+ {
+ up += un - n_limbs_needed;
+ un = n_limbs_needed;
+ }
+ pp = TMP_ALLOC_LIMBS (2 * n_limbs_needed + 2);
+ tp = TMP_ALLOC_LIMBS (2 * n_limbs_needed + 2);
+
+ pn = mpn_pow_1_highpart (pp, &ign, (mp_limb_t) base, e, n_limbs_needed, tp);
+
+ xn = n_limbs_needed + (n_less_limbs_needed-ign);
+ xp = TMP_ALLOC_LIMBS (xn);
+ off = xn - un;
+ MPN_ZERO (xp, off);
+ MPN_COPY (xp + off, up, un);
+
+ dummyp = TMP_ALLOC_LIMBS (pn);
+ mpn_tdiv_qr (tp, dummyp, (mp_size_t) 0, xp, xn, pp, pn);
+ tn = xn - pn + 1;
+ tn -= tp[tn - 1] == 0;
+ n_digits_computed = mpn_get_str (tstr, base, tp, tn);
+
+ exp_in_base = n_digits_computed + e;
+ }
+
+ /* We should normally have computed too many digits. Round the result
+ at the point indicated by n_digits. */
+ if (n_digits_computed > n_digits)
+ {
+ size_t i;
+ /* Round the result. */
+ if (tstr[n_digits] * 2 >= base)
+ {
+ n_digits_computed = n_digits;
+ for (i = n_digits - 1;; i--)
+ {
+ unsigned int x;
+ x = ++(tstr[i]);
+ if (x != base)
+ break;
+ n_digits_computed--;
+ if (i == 0)
+ {
+ /* We had something like `bbbbbbb...bd', where 2*d >= base
+ and `b' denotes digit with significance base - 1.
+ This rounds up to `1', increasing the exponent. */
+ tstr[0] = 1;
+ n_digits_computed = 1;
+ exp_in_base++;
+ break;
+ }
+ }
+ }
+ }
+
+ /* We might have fewer digits than requested as a result of rounding above,
+ (i.e. 0.999999 => 1.0) or because we have a number that simply doesn't
+ need many digits in this base (e.g., 0.125 in base 10). */
+ if (n_digits > n_digits_computed)
+ n_digits = n_digits_computed;
+
+ /* Remove trailing 0. There can be many zeros. */
+ while (n_digits != 0 && tstr[n_digits - 1] == 0)
+ n_digits--;
+
+ dp = dbuf + (SIZ(u) < 0);
+
+ /* Translate to ASCII and copy to result string. */
+ for (i = 0; i < n_digits; i++)
+ dp[i] = num_to_text[tstr[i]];
+ dp[n_digits] = 0;
+
+ *exp = exp_in_base;
+
+ if (SIZ(u) < 0)
+ {
+ dbuf[0] = '-';
+ n_digits++;
+ }
+
+ TMP_FREE;
+
+ done:
+ /* If the string was alloced then resize it down to the actual space
+ required. */
+ if (alloc_size != 0)
+ {
+ __GMP_REALLOCATE_FUNC_MAYBE_TYPE (dbuf, alloc_size, n_digits + 1, char);
+ }
+
+ return dbuf;
+}
projects / msp430-gcc.git / blobdiff