[project @ 1996-01-08 20:28:12 by partain]
[ghc.git] / ghc / runtime / gmp / mpz_mdm.c
1 /* mpz_mdivmod -- Mathematical DIVision and MODulo, i.e. division that rounds
2 the quotient towards -infinity, and with the remainder non-negative.
3
4 Copyright (C) 1991, 1992 Free Software Foundation, Inc.
5
6 This file is part of the GNU MP Library.
7
8 The GNU MP Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
11 any later version.
12
13 The GNU MP Library is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with the GNU MP Library; see the file COPYING. If not, write to
20 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21
22 #include "gmp.h"
23 #include "gmp-impl.h"
24
25 void
26 #ifdef __STDC__
27 mpz_mdivmod (MP_INT *quot, MP_INT *rem,
28 const MP_INT *dividend, const MP_INT *divisor)
29 #else
30 mpz_mdivmod (quot, rem, dividend, divisor)
31 MP_INT *quot;
32 MP_INT *rem;
33 const MP_INT *dividend;
34 const MP_INT *divisor;
35 #endif
36 {
37 if ((dividend->size ^ divisor->size) >= 0)
38 {
39 /* When the dividend and the divisor has same sign, this function
40 gives same result as mpz_divmod. */
41 mpz_divmod (quot, rem, dividend, divisor);
42 }
43 else
44 {
45 MP_INT temp_divisor; /* N.B.: lives until function returns! */
46
47 /* We need the original value of the divisor after the quotient and
48 remainder have been preliminary calculated. We have to copy it to
49 temporary space if it's the same variable as either QUOT or REM. */
50 if (quot == divisor || rem == divisor)
51 {
52 MPZ_TMP_INIT (&temp_divisor, ABS (divisor->size));
53 mpz_set (&temp_divisor, divisor);
54 divisor = &temp_divisor;
55 }
56
57 mpz_divmod (quot, rem, dividend, divisor);
58 if (rem->size != 0)
59 {
60 mpz_sub_ui (quot, quot, 1);
61 mpz_add (rem, rem, divisor);
62 }
63 }
64 }