118 lines
3.1 KiB

/* mpz_div -- divide two integers and produce a quotient.
Copyright (C) 1991 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 General Public License as published by
the Free Software Foundation; either version 2, 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
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU MP Library; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#ifdef __STDC__
mpz_div (MP_INT *quot, const MP_INT *num, const MP_INT *den)
mpz_div (quot, num, den)
MP_INT *quot;
const MP_INT *num;
const MP_INT *den;
mp_srcptr np, dp;
mp_ptr qp, rp;
mp_size nsize = num->size;
mp_size dsize = den->size;
mp_size qsize, rsize;
mp_size sign_quotient = nsize ^ dsize;
unsigned normalization_steps;
nsize = ABS (nsize);
dsize = ABS (dsize);
/* Ensure space is enough for quotient. */
qsize = nsize - dsize + 1; /* qsize cannot be bigger than this. */
if (qsize <= 0)
quot->size = 0;
if (quot->alloc < qsize)
_mpz_realloc (quot, qsize);
qp = quot->d;
np = num->d;
dp = den->d;
rp = (mp_ptr) alloca ((nsize + 1) * BYTES_PER_MP_LIMB);
count_leading_zeros (normalization_steps, dp[dsize - 1]);
/* Normalize the denominator and the numerator. */
if (normalization_steps != 0)
mp_ptr tp;
mp_limb ndigit;
/* 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) alloca (dsize * BYTES_PER_MP_LIMB);
(void) 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. */
ndigit = mpn_lshift (rp, np, nsize, normalization_steps);
if (ndigit != 0)
rp[nsize] = ndigit;
rsize = nsize + 1;
rsize = nsize;
/* The denominator is already normalized, as required.
Copy it to temporary space if it overlaps with the quotient. */
if (dp == qp)
dp = (mp_ptr) alloca (dsize * BYTES_PER_MP_LIMB);
MPN_COPY ((mp_ptr) dp, qp, dsize);
/* Move the numerator to the remainder. */
MPN_COPY (rp, np, nsize);
rsize = nsize;
qsize = rsize - dsize + mpn_div (qp, rp, rsize, dp, dsize);
/* Normalize the quotient. We may have at most one leading
zero-word, so no loop is needed. */
if (qsize > 0)
qsize -= (qp[qsize - 1] == 0);
if (sign_quotient < 0)
qsize = -qsize;
quot->size = qsize;
alloca (0);