--- /dev/null
+/* mpfr_div -- divide two floating-point numbers
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR 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 2.1 of the License, or (at your
+option) any later version.
+
+The GNU 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MPFR Library; see the file COPYING.LIB. If not, write to
+the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+MA 02110-1301, USA. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+#ifdef DEBUG2
+#define mpfr_mpn_print(ap,n) mpfr_mpn_print3 (ap,n,MPFR_LIMB_ZERO)
+static void
+mpfr_mpn_print3 (mp_ptr ap, mp_size_t n, mp_limb_t cy)
+{
+ mp_size_t i;
+ for (i = 0; i < n; i++)
+ printf ("+%lu*2^%lu", (unsigned long) ap[i], (unsigned long)
+ (BITS_PER_MP_LIMB * i));
+ if (cy)
+ printf ("+2^%lu", (unsigned long) (BITS_PER_MP_LIMB * n));
+ printf ("\n");
+}
+#endif
+
+/* check if {ap, an} is zero */
+static int
+mpfr_mpn_cmpzero (mp_ptr ap, mp_size_t an)
+{
+ while (an > 0)
+ if (MPFR_LIKELY(ap[--an] != MPFR_LIMB_ZERO))
+ return 1;
+ return 0;
+}
+
+/* compare {ap, an} and {bp, bn} >> extra,
+ aligned by the more significant limbs.
+ Takes into account bp[0] for extra=1.
+*/
+static int
+mpfr_mpn_cmp_aux (mp_ptr ap, mp_size_t an, mp_ptr bp, mp_size_t bn, int extra)
+{
+ int cmp = 0;
+ mp_size_t k;
+ mp_limb_t bb;
+
+ if (an >= bn)
+ {
+ k = an - bn;
+ while (cmp == 0 && bn > 0)
+ {
+ bn --;
+ bb = (extra) ? ((bp[bn+1] << (BITS_PER_MP_LIMB - 1)) | (bp[bn] >> 1))
+ : bp[bn];
+ cmp = (ap[k + bn] > bb) ? 1 : ((ap[k + bn] < bb) ? -1 : 0);
+ }
+ bb = (extra) ? bp[0] << (BITS_PER_MP_LIMB - 1) : MPFR_LIMB_ZERO;
+ while (cmp == 0 && k > 0)
+ {
+ k--;
+ cmp = (ap[k] > bb) ? 1 : ((ap[k] < bb) ? -1 : 0);
+ bb = MPFR_LIMB_ZERO; /* ensure we consider only once bp[0] & 1 */
+ }
+ if (cmp == 0 && bb != MPFR_LIMB_ZERO)
+ cmp = -1;
+ }
+ else /* an < bn */
+ {
+ k = bn - an;
+ while (cmp == 0 && an > 0)
+ {
+ an --;
+ bb = (extra) ? ((bp[k+an+1] << (BITS_PER_MP_LIMB - 1)) | (bp[k+an] >> 1))
+ : bp[k+an];
+ if (ap[an] > bb)
+ cmp = 1;
+ else if (ap[an] < bb)
+ cmp = -1;
+ }
+ while (cmp == 0 && k > 0)
+ {
+ k--;
+ bb = (extra) ? ((bp[k+1] << (BITS_PER_MP_LIMB - 1)) | (bp[k] >> 1))
+ : bp[k];
+ cmp = (bb != MPFR_LIMB_ZERO) ? -1 : 0;
+ }
+ if (cmp == 0 && extra && (bp[0] & MPFR_LIMB_ONE))
+ cmp = -1;
+ }
+ return cmp;
+}
+
+/* {ap, n} <- {ap, n} - {bp, n} >> extra - cy, with cy = 0 or 1.
+ Return borrow out.
+*/
+static mp_limb_t
+mpfr_mpn_sub_aux (mp_ptr ap, mp_ptr bp, mp_size_t n, mp_limb_t cy, int extra)
+{
+ mp_limb_t bb, rp;
+
+ MPFR_ASSERTD (cy <= 1);
+ while (n--)
+ {
+ bb = (extra) ? ((bp[1] << (BITS_PER_MP_LIMB-1)) | (bp[0] >> 1)) : bp[0];
+ rp = ap[0] - bb - cy;
+ cy = (ap[0] < bb) || (cy && ~rp == MPFR_LIMB_ZERO) ?
+ MPFR_LIMB_ONE : MPFR_LIMB_ZERO;
+ ap[0] = rp;
+ ap ++;
+ bp ++;
+ }
+ MPFR_ASSERTD (cy <= 1);
+ return cy;
+}
+
+int
+mpfr_div (mpfr_ptr q, mpfr_srcptr u, mpfr_srcptr v, mp_rnd_t rnd_mode)
+{
+ mp_size_t q0size = MPFR_LIMB_SIZE(q); /* number of limbs of destination */
+ mp_size_t usize = MPFR_LIMB_SIZE(u);
+ mp_size_t vsize = MPFR_LIMB_SIZE(v);
+ mp_size_t qsize; /* number of limbs of the computed quotient */
+ mp_size_t qqsize;
+ mp_size_t k;
+ mp_ptr q0p = MPFR_MANT(q), qp;
+ mp_ptr up = MPFR_MANT(u);
+ mp_ptr vp = MPFR_MANT(v);
+ mp_ptr ap;
+ mp_ptr bp;
+ mp_limb_t qh;
+ mp_limb_t sticky_u = MPFR_LIMB_ZERO;
+ mp_limb_t low_u;
+ mp_limb_t sticky_v = MPFR_LIMB_ZERO;
+ mp_limb_t sticky;
+ mp_limb_t sticky3;
+ mp_limb_t round_bit = MPFR_LIMB_ZERO;
+ mp_exp_t qexp;
+ int sign_quotient;
+ int extra_bit;
+ int sh, sh2;
+ int inex;
+ int like_rndz;
+ MPFR_TMP_DECL(marker);
+
+ MPFR_LOG_FUNC (("u[%#R]=%R v[%#R]=%R rnd=%d", u, u, v, v, rnd_mode),
+ ("q[%#R]=%R inexact=%d", q, q, inex));
+
+ /**************************************************************************
+ * *
+ * This part of the code deals with special cases *
+ * *
+ **************************************************************************/
+
+ if (MPFR_UNLIKELY(MPFR_ARE_SINGULAR(u,v)))
+ {
+ if (MPFR_IS_NAN(u) || MPFR_IS_NAN(v))
+ {
+ MPFR_SET_NAN(q);
+ MPFR_RET_NAN;
+ }
+ sign_quotient = MPFR_MULT_SIGN( MPFR_SIGN(u) , MPFR_SIGN(v) );
+ MPFR_SET_SIGN(q, sign_quotient);
+ if (MPFR_IS_INF(u))
+ {
+ if (MPFR_IS_INF(v))
+ {
+ MPFR_SET_NAN(q);
+ MPFR_RET_NAN;
+ }
+ else
+ {
+ MPFR_SET_INF(q);
+ MPFR_RET(0);
+ }
+ }
+ else if (MPFR_IS_INF(v))
+ {
+ MPFR_SET_ZERO (q);
+ MPFR_RET (0);
+ }
+ else if (MPFR_IS_ZERO (v))
+ {
+ if (MPFR_IS_ZERO (u))
+ {
+ MPFR_SET_NAN(q);
+ MPFR_RET_NAN;
+ }
+ else
+ {
+ MPFR_SET_INF(q);
+ MPFR_RET(0);
+ }
+ }
+ else
+ {
+ MPFR_ASSERTD (MPFR_IS_ZERO (u));
+ MPFR_SET_ZERO (q);
+ MPFR_RET (0);
+ }
+ }
+ MPFR_CLEAR_FLAGS (q);
+
+ /**************************************************************************
+ * *
+ * End of the part concerning special values. *
+ * *
+ **************************************************************************/
+
+ MPFR_TMP_MARK(marker);
+
+ /* set sign */
+ sign_quotient = MPFR_MULT_SIGN( MPFR_SIGN(u) , MPFR_SIGN(v) );
+ MPFR_SET_SIGN(q, sign_quotient);
+
+ /* determine if an extra bit comes from the division, i.e. if the
+ significand of u (as a fraction in [1/2, 1[) is larger than that
+ of v */
+ if (MPFR_LIKELY(up[usize - 1] != vp[vsize - 1]))
+ extra_bit = (up[usize - 1] > vp[vsize - 1]) ? 1 : 0;
+ else /* most significant limbs are equal, must look at further limbs */
+ {
+ mp_size_t l;
+
+ k = usize - 1;
+ l = vsize - 1;
+ while (k != 0 && l != 0 && up[--k] == vp[--l]);
+ /* now k=0 or l=0 or up[k] != vp[l] */
+ if (up[k] > vp[l])
+ extra_bit = 1;
+ else if (up[k] < vp[l])
+ extra_bit = 0;
+ /* now up[k] = vp[l], thus either k=0 or l=0 */
+ else if (l == 0) /* no more divisor limb */
+ extra_bit = 1;
+ else /* k=0: no more dividend limb */
+ extra_bit = mpfr_mpn_cmpzero (vp, l) == 0;
+ }
+#ifdef DEBUG
+ printf ("extra_bit=%d\n", extra_bit);
+#endif
+
+ /* set exponent */
+ qexp = MPFR_GET_EXP (u) - MPFR_GET_EXP (v) + extra_bit;
+
+ MPFR_UNSIGNED_MINUS_MODULO(sh, MPFR_PREC(q));
+
+ if (MPFR_UNLIKELY(rnd_mode == GMP_RNDN && sh == 0))
+ { /* we compute the quotient with one more limb, in order to get
+ the round bit in the quotient, and the remainder only contains
+ sticky bits */
+ qsize = q0size + 1;
+ /* need to allocate memory for the quotient */
+ qp = (mp_ptr) MPFR_TMP_ALLOC (qsize * sizeof(mp_limb_t));
+ }
+ else
+ {
+ qsize = q0size;
+ qp = q0p; /* directly put the quotient in the destination */
+ }
+ qqsize = qsize + qsize;
+
+ /* prepare the dividend */
+ ap = (mp_ptr) MPFR_TMP_ALLOC (qqsize * sizeof(mp_limb_t));
+ if (MPFR_LIKELY(qqsize > usize)) /* use the full dividend */
+ {
+ k = qqsize - usize; /* k > 0 */
+ MPN_ZERO(ap, k);
+ if (extra_bit)
+ ap[k - 1] = mpn_rshift (ap + k, up, usize, 1);
+ else
+ MPN_COPY(ap + k, up, usize);
+ }
+ else /* truncate the dividend */
+ {
+ k = usize - qqsize;
+ if (extra_bit)
+ sticky_u = mpn_rshift (ap, up + k, qqsize, 1);
+ else
+ MPN_COPY(ap, up + k, qqsize);
+ sticky_u = sticky_u || mpfr_mpn_cmpzero (up, k);
+ }
+ low_u = sticky_u;
+
+ /* now sticky_u is non-zero iff the truncated part of u is non-zero */
+
+ /* prepare the divisor */
+ if (MPFR_LIKELY(vsize >= qsize))
+ {
+ k = vsize - qsize;
+ if (qp != vp)
+ bp = vp + k; /* avoid copying the divisor */
+ else /* need to copy, since mpn_divrem doesn't allow overlap
+ between quotient and divisor, necessarily k = 0
+ since quotient and divisor are the same mpfr variable */
+ {
+ bp = (mp_ptr) MPFR_TMP_ALLOC (qsize * sizeof(mp_limb_t));
+ MPN_COPY(bp, vp, vsize);
+ }
+ sticky_v = sticky_v || mpfr_mpn_cmpzero (vp, k);
+ k = 0;
+ }
+ else /* vsize < qsize: small divisor case */
+ {
+ bp = vp;
+ k = qsize - vsize;
+ }
+
+ /* we now can perform the division */
+ qh = mpn_divrem (qp, 0, ap + k, qqsize - k, bp, qsize - k);
+ /* warning: qh may be 1 if u1 == v1, but u < v */
+#ifdef DEBUG2
+ printf ("q="); mpfr_mpn_print (qp, qsize);
+ printf ("r="); mpfr_mpn_print (ap, qsize);
+#endif
+
+ k = qsize;
+ sticky_u = sticky_u || mpfr_mpn_cmpzero (ap, k);
+
+ sticky = sticky_u | sticky_v;
+
+ /* now sticky is non-zero iff one of the following holds:
+ (a) the truncated part of u is non-zero
+ (b) the truncated part of v is non-zero
+ (c) the remainder from division is non-zero */
+
+ if (MPFR_LIKELY(qsize == q0size))
+ {
+ sticky3 = qp[0] & MPFR_LIMB_MASK(sh); /* does nothing when sh=0 */
+ sh2 = sh;
+ }
+ else /* qsize = q0size + 1: only happens when rnd_mode=GMP_RNDN and sh=0 */
+ {
+ MPN_COPY (q0p, qp + 1, q0size);
+ sticky3 = qp[0];
+ sh2 = BITS_PER_MP_LIMB;
+ }
+ qp[0] ^= sticky3;
+ /* sticky3 contains the truncated bits from the quotient,
+ including the round bit, and 1 <= sh2 <= BITS_PER_MP_LIMB
+ is the number of bits in sticky3 */
+ inex = (sticky != MPFR_LIMB_ZERO) || (sticky3 != MPFR_LIMB_ZERO);
+#ifdef DEBUG
+ printf ("sticky=%lu sticky3=%lu inex=%d\n",
+ (unsigned long) sticky, (unsigned long) sticky3, inex);
+#endif
+
+ like_rndz = rnd_mode == GMP_RNDZ ||
+ rnd_mode == (sign_quotient < 0 ? GMP_RNDU : GMP_RNDD);
+
+ /* to round, we distinguish two cases:
+ (a) vsize <= qsize: we used the full divisor
+ (b) vsize > qsize: the divisor was truncated
+ */
+
+#ifdef DEBUG
+ printf ("vsize=%lu qsize=%lu\n",
+ (unsigned long) vsize, (unsigned long) qsize);
+#endif
+ if (MPFR_LIKELY(vsize <= qsize)) /* use the full divisor */
+ {
+ if (MPFR_LIKELY(rnd_mode == GMP_RNDN))
+ {
+ round_bit = sticky3 & (MPFR_LIMB_ONE << (sh2 - 1));
+ sticky = (sticky3 ^ round_bit) | sticky_u;
+ }
+ else if (like_rndz || inex == 0)
+ sticky = (inex == 0) ? MPFR_LIMB_ZERO : MPFR_LIMB_ONE;
+ else /* round away from zero */
+ sticky = MPFR_LIMB_ONE;
+ goto case_1;
+ }
+ else /* vsize > qsize: need to truncate the divisor */
+ {
+ if (inex == 0)
+ goto truncate;
+ else
+ {
+ /* We know the estimated quotient is an upper bound of the exact
+ quotient (with rounding towards zero), with a difference of at
+ most 2 in qp[0].
+ Thus we can round except when sticky3 is 000...000 or 000...001
+ for directed rounding, and 100...000 or 100...001 for rounding
+ to nearest. (For rounding to nearest, we cannot determine the
+ inexact flag for 000...000 or 000...001.)
+ */
+ mp_limb_t sticky3orig = sticky3;
+ if (rnd_mode == GMP_RNDN)
+ {
+ round_bit = sticky3 & (MPFR_LIMB_ONE << (sh2 - 1));
+ sticky3 = sticky3 ^ round_bit;
+#ifdef DEBUG
+ printf ("rb=%lu sb=%lu\n",
+ (unsigned long) round_bit, (unsigned long) sticky3);
+#endif
+ }
+ if (sticky3 != MPFR_LIMB_ZERO && sticky3 != MPFR_LIMB_ONE)
+ {
+ sticky = sticky3;
+ goto case_1;
+ }
+ else /* hard case: we have to compare q1 * v0 and r + low(u),
+ where q1 * v0 has qsize + (vsize-qsize) = vsize limbs, and
+ r + low(u) has qsize + (usize-2*qsize) = usize-qsize limbs */
+ {
+ mp_size_t l;
+ mp_ptr sp;
+ int cmp_s_r;
+ mp_limb_t qh2;
+
+ sp = (mp_ptr) MPFR_TMP_ALLOC (vsize * sizeof(mp_limb_t));
+ k = vsize - qsize;
+ /* sp <- {qp, qsize} * {vp, vsize-qsize} */
+ qp[0] ^= sticky3orig; /* restore original quotient */
+ if (qsize >= k)
+ mpn_mul (sp, qp, qsize, vp, k);
+ else
+ mpn_mul (sp, vp, k, qp, qsize);
+ if (qh)
+ qh2 = mpn_add_n (sp + qsize, sp + qsize, vp, k);
+ else
+ qh2 = (mp_limb_t) 0;
+ qp[0] ^= sticky3orig; /* restore truncated quotient */
+
+ /* compare qh2 + {sp, k + qsize} to {ap, qsize} + low(u) */
+ cmp_s_r = (qh2 != 0) ? 1 : mpn_cmp (sp + k, ap, qsize);
+ if (cmp_s_r == 0) /* compare {sp, k} and low(u) */
+ {
+ cmp_s_r = (usize >= qqsize) ?
+ mpfr_mpn_cmp_aux (sp, k, up, usize - qqsize, extra_bit) :
+ mpfr_mpn_cmpzero (sp, k);
+ }
+#ifdef DEBUG
+ printf ("cmp(q*v0,r+u0)=%d\n", cmp_s_r);
+#endif
+ /* now cmp_s_r > 0 if {sp, vsize} > {ap, qsize} + low(u)
+ cmp_s_r = 0 if {sp, vsize} = {ap, qsize} + low(u)
+ cmp_s_r < 0 if {sp, vsize} < {ap, qsize} + low(u) */
+ if (cmp_s_r <= 0) /* quotient is in [q1, q1+1) */
+ {
+ sticky = (cmp_s_r == 0) ? sticky3 : MPFR_LIMB_ONE;
+ goto case_1;
+ }
+ else /* cmp_s_r > 0, quotient is < q1: to determine if it is
+ in [q1-2,q1-1] or in [q1-1,q1], we need to subtract
+ the low part u0 of the dividend u0 from q*v0 */
+ {
+ mp_limb_t cy = MPFR_LIMB_ZERO;
+
+ /* subtract low(u)>>extra_bit if non-zero */
+ if (qh2 != 0) /* whatever the value of {up, m + k}, it
+ will be smaller than qh2 + {sp, k} */
+ cmp_s_r = 1;
+ else
+ {
+ if (low_u != MPFR_LIMB_ZERO)
+ {
+ mp_size_t m;
+ l = usize - qqsize; /* number of low limbs in u */
+ m = (l > k) ? l - k : 0;
+ cy = (extra_bit) ?
+ (up[m] & MPFR_LIMB_ONE) : MPFR_LIMB_ZERO;
+ if (l >= k) /* u0 has more limbs than s:
+ first look if {up, m} is not zero,
+ and compare {sp, k} and {up + m, k} */
+ {
+ cy = cy || mpfr_mpn_cmpzero (up, m);
+ low_u = cy;
+ cy = mpfr_mpn_sub_aux (sp, up + m, k,
+ cy, extra_bit);
+ }
+ else /* l < k: s has more limbs than u0 */
+ {
+ low_u = MPFR_LIMB_ZERO;
+ if (cy != MPFR_LIMB_ZERO)
+ cy = mpn_sub_1 (sp + k - l - 1, sp + k - l - 1,
+ 1, MPFR_LIMB_HIGHBIT);
+ cy = mpfr_mpn_sub_aux (sp + k - l, up, l,
+ cy, extra_bit);
+ }
+ }
+ MPFR_ASSERTD (cy <= 1);
+ cy = mpn_sub_1 (sp + k, sp + k, qsize, cy);
+ /* subtract r */
+ cy += mpn_sub_n (sp + k, sp + k, ap, qsize);
+ MPFR_ASSERTD (cy <= 1);
+ /* now compare {sp, ssize} to v */
+ cmp_s_r = mpn_cmp (sp, vp, vsize);
+ if (cmp_s_r == 0 && low_u != MPFR_LIMB_ZERO)
+ cmp_s_r = 1; /* since in fact we subtracted
+ less than 1 */
+ }
+#ifdef DEBUG
+ printf ("cmp(q*v0-(r+u0),v)=%d\n", cmp_s_r);
+#endif
+ if (cmp_s_r <= 0) /* q1-1 <= u/v < q1 */
+ {
+ if (sticky3 == MPFR_LIMB_ONE)
+ { /* q1-1 is either representable (directed rounding),
+ or the middle of two numbers (nearest) */
+ sticky = (cmp_s_r) ? MPFR_LIMB_ONE : MPFR_LIMB_ZERO;
+ goto case_1;
+ }
+ /* now necessarily sticky3=0 */
+ else if (round_bit == MPFR_LIMB_ZERO)
+ { /* round_bit=0, sticky3=0: q1-1 is exact only
+ when sh=0 */
+ inex = (cmp_s_r || sh) ? -1 : 0;
+ if (rnd_mode == GMP_RNDN ||
+ (! like_rndz && inex != 0))
+ {
+ inex = 1;
+ goto truncate_check_qh;
+ }
+ else /* round down */
+ goto sub_one_ulp;
+ }
+ else /* sticky3=0, round_bit=1 ==> rounding to nearest */
+ {
+ inex = cmp_s_r;
+ goto truncate;
+ }
+ }
+ else /* q1-2 < u/v < q1-1 */
+ {
+ /* if rnd=GMP_RNDN, the result is q1 when
+ q1-2 >= q1-2^(sh-1), i.e. sh >= 2,
+ otherwise (sh=1) it is q1-2 */
+ if (rnd_mode == GMP_RNDN) /* sh > 0 */
+ {
+ /* Case sh=1: sb=0 always, and q1-rb is exactly
+ representable, like q1-rb-2.
+ rb action
+ 0 subtract two ulps, inex=-1
+ 1 truncate, inex=1
+
+ Case sh>1: one ulp is 2^(sh-1) >= 2
+ rb sb action
+ 0 0 truncate, inex=1
+ 0 1 truncate, inex=1
+ 1 x truncate, inex=-1
+ */
+ if (sh == 1)
+ {
+ if (round_bit == MPFR_LIMB_ZERO)
+ {
+ inex = -1;
+ sh = 0;
+ goto sub_two_ulp;
+ }
+ else
+ {
+ inex = 1;
+ goto truncate_check_qh;
+ }
+ }
+ else /* sh > 1 */
+ {
+ inex = (round_bit == MPFR_LIMB_ZERO) ? 1 : -1;
+ goto truncate_check_qh;
+ }
+ }
+ else if (like_rndz)
+ {
+ /* the result is down(q1-2), i.e. subtract one
+ ulp if sh > 0, and two ulps if sh=0 */
+ inex = -1;
+ if (sh > 0)
+ goto sub_one_ulp;
+ else
+ goto sub_two_ulp;
+ }
+ /* if round away from zero, the result is up(q1-1),
+ which is q1 unless sh = 0, where it is q1-1 */
+ else
+ {
+ inex = 1;
+ if (sh > 0)
+ goto truncate_check_qh;
+ else /* sh = 0 */
+ goto sub_one_ulp;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ case_1: /* quotient is in [q1, q1+1),
+ round_bit is the round_bit (0 for directed rounding),
+ sticky the sticky bit */
+ if (like_rndz || (round_bit == MPFR_LIMB_ZERO && sticky == MPFR_LIMB_ZERO))
+ {
+ inex = round_bit == MPFR_LIMB_ZERO && sticky == MPFR_LIMB_ZERO ? 0 : -1;
+ goto truncate;
+ }
+ else if (rnd_mode == GMP_RNDN) /* sticky <> 0 or round <> 0 */
+ {
+ if (round_bit == MPFR_LIMB_ZERO) /* necessarily sticky <> 0 */
+ {
+ inex = -1;
+ goto truncate;
+ }
+ /* round_bit = 1 */
+ else if (sticky != MPFR_LIMB_ZERO)
+ goto add_one_ulp; /* inex=1 */
+ else /* round_bit=1, sticky=0 */
+ goto even_rule;
+ }
+ else /* round away from zero, sticky <> 0 */
+ goto add_one_ulp; /* with inex=1 */
+
+ sub_two_ulp:
+ /* we cannot subtract MPFR_LIMB_MPFR_LIMB_ONE << (sh+1) since this is
+ undefined for sh = BITS_PER_MP_LIMB */
+ qh -= mpn_sub_1 (q0p, q0p, q0size, MPFR_LIMB_ONE << sh);
+ /* go through */
+
+ sub_one_ulp:
+ qh -= mpn_sub_1 (q0p, q0p, q0size, MPFR_LIMB_ONE << sh);
+ /* go through truncate_check_qh */
+
+ truncate_check_qh:
+ if (qh)
+ {
+ qexp ++;
+ q0p[q0size - 1] = MPFR_LIMB_HIGHBIT;
+ }
+ goto truncate;
+
+ even_rule: /* has to set inex */
+ inex = (q0p[0] & (MPFR_LIMB_ONE << sh)) ? 1 : -1;
+ if (inex < 0)
+ goto truncate;
+ /* else go through add_one_ulp */
+
+ add_one_ulp:
+ inex = 1; /* always here */
+ if (mpn_add_1 (q0p, q0p, q0size, MPFR_LIMB_ONE << sh))
+ {
+ qexp ++;
+ q0p[q0size - 1] = MPFR_LIMB_HIGHBIT;
+ }
+
+ truncate: /* inex already set */
+
+ MPFR_TMP_FREE(marker);
+
+ /* check for underflow/overflow */
+ if (MPFR_UNLIKELY(qexp > __gmpfr_emax))
+ return mpfr_overflow (q, rnd_mode, sign_quotient);
+ else if (MPFR_UNLIKELY(qexp < __gmpfr_emin))
+ {
+ if (rnd_mode == GMP_RNDN && ((qexp < __gmpfr_emin - 1) ||
+ (inex >= 0 && mpfr_powerof2_raw (q))))
+ rnd_mode = GMP_RNDZ;
+ return mpfr_underflow (q, rnd_mode, sign_quotient);
+ }
+ MPFR_SET_EXP(q, qexp);
+
+ inex *= sign_quotient;
+ MPFR_RET (inex);
+}
projects / msp430-gcc.git / blobdiff