145 lines
3.5 KiB
C
145 lines
3.5 KiB
C
/* mpf_div -- Divide two floats.
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Copyright (C) 1993, 1994, 1996 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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void
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#if __STDC__
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mpf_div (mpf_ptr r, mpf_srcptr u, mpf_srcptr v)
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#else
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mpf_div (r, u, v)
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mpf_ptr r;
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mpf_srcptr u;
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mpf_srcptr v;
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#endif
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{
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mp_srcptr up, vp;
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mp_ptr rp, tp, rtp;
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mp_size_t usize, vsize;
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mp_size_t rsize, tsize;
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mp_size_t sign_quotient;
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mp_size_t prec;
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unsigned normalization_steps;
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mp_limb_t q_limb;
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mp_exp_t rexp;
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TMP_DECL (marker);
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usize = u->_mp_size;
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vsize = v->_mp_size;
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sign_quotient = usize ^ vsize;
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usize = ABS (usize);
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vsize = ABS (vsize);
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prec = r->_mp_prec;
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if (vsize == 0)
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vsize = 1 / vsize; /* divide by zero as directed */
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if (usize == 0)
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{
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r->_mp_size = 0;
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r->_mp_exp = 0;
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return;
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}
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TMP_MARK (marker);
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rexp = u->_mp_exp - v->_mp_exp;
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rp = r->_mp_d;
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up = u->_mp_d;
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vp = v->_mp_d;
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if (vsize > prec)
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{
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vp += vsize - prec;
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vsize = prec;
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}
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tsize = vsize + prec;
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tp = (mp_ptr) TMP_ALLOC ((tsize + 1) * BYTES_PER_MP_LIMB);
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if (usize > tsize)
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{
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up += usize - tsize;
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usize = tsize;
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rtp = tp;
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}
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else
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{
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MPN_ZERO (tp, tsize - usize);
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rtp = tp + (tsize - usize);
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}
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count_leading_zeros (normalization_steps, vp[vsize - 1]);
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/* Normalize the divisor and the dividend. */
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if (normalization_steps != 0)
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{
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mp_ptr tmp;
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mp_limb_t nlimb;
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/* Shift up the divisor setting the most significant bit of
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the most significant limb. Use temporary storage not to clobber
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the original contents of the divisor. */
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tmp = (mp_ptr) TMP_ALLOC (vsize * BYTES_PER_MP_LIMB);
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mpn_lshift (tmp, vp, vsize, normalization_steps);
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vp = tmp;
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/* Shift up the dividend, possibly introducing a new most
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significant word. Move the shifted dividend in the remainder
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at the same time. */
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nlimb = mpn_lshift (rtp, up, usize, normalization_steps);
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if (nlimb != 0)
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{
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rtp[usize] = nlimb;
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tsize++;
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rexp++;
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}
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}
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else
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{
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/* The divisor is already normalized, as required.
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Copy it to temporary space if it overlaps with the quotient. */
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if (vp - rp <= tsize - vsize)
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{
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mp_ptr tmp = (mp_ptr) TMP_ALLOC (vsize * BYTES_PER_MP_LIMB);
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MPN_COPY (tmp, vp, vsize);
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vp = (mp_srcptr) tmp;
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}
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/* Move the dividend to the remainder. */
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MPN_COPY (rtp, up, usize);
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}
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q_limb = mpn_divmod (rp, tp, tsize, vp, vsize);
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rsize = tsize - vsize;
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if (q_limb)
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{
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rp[rsize] = q_limb;
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rsize++;
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rexp++;
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}
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r->_mp_size = sign_quotient >= 0 ? rsize : -rsize;
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r->_mp_exp = rexp;
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TMP_FREE (marker);
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}
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