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/* dmincl.c -- include file for tdiv_qr.c, tdiv_r.c.
Copyright (C) 1991, 1993, 1994, 1996 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 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 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the GNU MP 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. */
/* If den == quot, den needs temporary storage.
If den == rem, den needs temporary storage.
If num == quot, num needs temporary storage.
If den has temporary storage, it can be normalized while being copied,
i.e no extra storage should be allocated. */
/* This is the function body of mdiv, mpz_divmod, and mpz_mod.
If COMPUTE_QUOTIENT is defined, the quotient is put in the MP_INT
object quot, otherwise that variable is not referenced at all.
The remainder is always computed, and the result is put in the MP_INT
object rem. */
{
mp_ptr np, dp;
mp_ptr qp, rp;
mp_size_t nsize = num->_mp_size;
mp_size_t dsize = den->_mp_size;
mp_size_t qsize, rsize;
mp_size_t sign_remainder = nsize;
#ifdef COMPUTE_QUOTIENT
mp_size_t sign_quotient = nsize ^ dsize;
#endif
unsigned normalization_steps;
mp_limb_t q_limb;
TMP_DECL (marker);
nsize = ABS (nsize);
dsize = ABS (dsize);
/* Ensure space is enough for quotient and remainder. */
/* We need space for an extra limb in the remainder, because it's
up-shifted (normalized) below. */
rsize = nsize + 1;
if (rem->_mp_alloc < rsize)
_mpz_realloc (rem, rsize);
qsize = rsize - dsize; /* qsize cannot be bigger than this. */
if (qsize <= 0)
{
if (num != rem)
{
rem->_mp_size = num->_mp_size;
MPN_COPY (rem->_mp_d, num->_mp_d, nsize);
}
#ifdef COMPUTE_QUOTIENT
/* This needs to follow the assignment to rem, in case the
numerator and quotient are the same. */
quot->_mp_size = 0;
#endif
return;
}
#ifdef COMPUTE_QUOTIENT
if (quot->_mp_alloc < qsize)
_mpz_realloc (quot, qsize);
#endif
/* Read pointers here, when reallocation is finished. */
np = num->_mp_d;
dp = den->_mp_d;
rp = rem->_mp_d;
/* Optimize division by a single-limb divisor. */
if (dsize == 1)
{
mp_limb_t rlimb;
#ifdef COMPUTE_QUOTIENT
qp = quot->_mp_d;
rlimb = mpn_divmod_1 (qp, np, nsize, dp[0]);
qsize -= qp[qsize - 1] == 0;
quot->_mp_size = sign_quotient >= 0 ? qsize : -qsize;
#else
rlimb = mpn_mod_1 (np, nsize, dp[0]);
#endif
rp[0] = rlimb;
rsize = rlimb != 0;
rem->_mp_size = sign_remainder >= 0 ? rsize : -rsize;
return;
}
TMP_MARK (marker);
#ifdef COMPUTE_QUOTIENT
qp = quot->_mp_d;
/* Make sure QP and NP point to different objects. Otherwise the
numerator would be gradually overwritten by the quotient limbs. */
if (qp == np)
{
/* Copy NP object to temporary space. */
np = (mp_ptr) TMP_ALLOC (nsize * BYTES_PER_MP_LIMB);
MPN_COPY (np, qp, nsize);
}
#else
/* Put quotient at top of remainder. */
qp = rp + dsize;
#endif
count_leading_zeros (normalization_steps, dp[dsize - 1]);
/* Normalize the denominator, i.e. make its most significant bit set by
shifting it NORMALIZATION_STEPS bits to the left. Also shift the
numerator the same number of steps (to keep the quotient the same!). */
if (normalization_steps != 0)
{
mp_ptr tp;
mp_limb_t nlimb;
/* Shift up the denominator setting the most significant bit of
the most significant word. Use temporary storage not to clobber
the original contents of the denominator. */
tp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
mpn_lshift (tp, dp, dsize, normalization_steps);
dp = tp;
/* Shift up the numerator, possibly introducing a new most
significant word. Move the shifted numerator in the remainder
meanwhile. */
nlimb = mpn_lshift (rp, np, nsize, normalization_steps);
if (nlimb != 0)
{
rp[nsize] = nlimb;
rsize = nsize + 1;
}
else
rsize = nsize;
}
else
{
/* The denominator is already normalized, as required. Copy it to
temporary space if it overlaps with the quotient or remainder. */
#ifdef COMPUTE_QUOTIENT
if (dp == rp || dp == qp)
#else
if (dp == rp)
#endif
{
mp_ptr tp;
tp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
MPN_COPY (tp, dp, dsize);
dp = tp;
}
/* Move the numerator to the remainder. */
if (rp != np)
MPN_COPY (rp, np, nsize);
rsize = nsize;
}
q_limb = mpn_divmod (qp, rp, rsize, dp, dsize);
#ifdef COMPUTE_QUOTIENT
qsize = rsize - dsize;
if (q_limb)
{
qp[qsize] = q_limb;
qsize += 1;
}
quot->_mp_size = sign_quotient >= 0 ? qsize : -qsize;
#endif
rsize = dsize;
MPN_NORMALIZE (rp, rsize);
if (normalization_steps != 0 && rsize != 0)
{
mpn_rshift (rp, rp, rsize, normalization_steps);
rsize -= rp[rsize - 1] == 0;
}
rem->_mp_size = sign_remainder >= 0 ? rsize : -rsize;
TMP_FREE (marker);
}
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